Category: Graphene Oxide

Graphene Functionalization

Posted on | by Energeia Graphenemex

Graphene Functionalization

Transforming Properties for Innovative Applications

Graphene is a carbon nanostructure in sheet form with multifunctional properties. Although it is usually chemically inert, under certain conditions and due to its extensive surface area, it can interact with other molecules or particles to generate a wide variety of derivatives with specific characteristics, as will be discussed below.

Chemically inert: incapable of reacting or inactive.

The interactions graphene can undergo are also known as functionalizations or dopings. These are chemical modifications aimed at giving graphene new properties or “functions.” For example, to make it hydrophilic, since it is well-known that graphene is inherently hydrophobic, making it challenging to manipulate. This quality leads to the most common functionalization, which involves anchoring oxygenated groups such as hydroxyl, epoxy, carbonyl, and carboxyl along its carbon structure, resulting in its most well-known variant: Graphene Oxide (GO).

“Graphene functionalization changes surface chemistry, such as charge and hydrophobicity.”

Covalent and Non-Covalent Functionalization

Graphene can be functionalized through covalent or non-covalent means. The former refers to the formation of strong chemical bonds with other particles or molecules that alter the structure and hybridization of its carbon atoms. This type of functionalization allows better control over the process compared to non-covalent functionalization (Van der Waals forces, electrostatic interactions, hydrogen bonding, or π-π stacking), which does not alter its chemical structure since the particles or molecules are adsorbed on its surface in a weaker and reversible manner.

“Graphene’s chemical functionalization is a vital tool for its integration into the world of applications.”

As mentioned earlier, the most well-known graphene functionalization is graphene oxide, also found in the literature as graphite oxide or oxidized graphene. This variant is defined as a single graphitic monolayer covalently functionalized with hydroxyl and epoxy groups above and below each graphene sheet, as well as carbonyl and carboxyl groups typically on its edges.

These modifications to the graphene structure have distinct advantages. For one, they improve its dispersion in aqueous media, prevent re-agglomeration, provide more interaction sites for additional functionalizations, facilitate incorporation into three-dimensional materials (e.g., polymers), and ultimately allow for greater production scalability of both GO and graphene itself. This is because the oxygenated groups anchored to the GO surface can be removed through chemical, electrochemical, or thermal methods that partially restore the graphene structure, making GO a precursor material.

This is significant because one reason there are few graphene applications in the market is that common production methods yield low or insufficient amounts for industrial use. Below are some examples of unrelated functionalizations of graphene and its derivatives for various applications.

Graphene Functionalization with Polymers

For proper graphene functionalization, it is essential to form strong bonds between graphene’s carbon atoms and polymers through covalent functionalizations. However, this is a complex task since graphene consists only of carbon and lacks functional groups for conjugation. For this reason, GO and reduced graphene oxide (rGO) are the primary precursors for graphene functionalization with polymers via non-covalent bonds.

One example is the direct functionalization of GO through π-π stacking during polymer extrusion processes, where high temperatures and strong shear forces fracture aggregates and allow polymer chains to diffuse into the GO sheets’ spaces, facilitating proper integration. In this way, GO can transfer its properties—primarily mechanical—to the polymer.

However, GO can also be functionalized with other structures, such as chitosan, to integrate into polymers like polyvinyl propylene (PVP) and polyvinyl alcohol (PVA) or directly functionalized with polymethyl methacrylate (PMMA) or polyethylene glycol (PEG) for bioapplications.

Another example of GO functionalization is with polyaniline, a conductive polymer, to create electrode materials with improved electrochemical performance and greater long-term stability. Similarly, functionalization with polypyrrole-based compounds enhances energy storage capacities. GO can also be functionalized with metallic nanoparticles like copper or silver to increase electrical conductivity in conductive coatings or inks.

Graphene Functionalization for Biomedical Applications

Dispersion stability of graphene is an essential requirement for success in all applications. For this reason, GO is the most commonly used variant. Additional functionalizations can be made through the oxygenated groups present across its surface, which not only improve graphene’s dispersion in water but also increase its biocompatibility and safety. Furthermore, its extensive surface area, including graphene’s intrinsic hydrophobic regions, allows the adsorption of organic molecules, DNA, RNA, proteins, ions, or polymers via non-covalent interactions (π-π stacking, hydrogen bonding, and electrostatic interactions) for various medical applications. Examples include designing biocatalytic platforms through functionalization with gold nanoparticles for use in diagnostic biosensors, with fluorescent pigments for imaging, with silver nanoparticles for antimicrobial purposes, or with polymers like polyethylene glycol for drug anchoring and delivery.

Graphene Functionalization for Photovoltaic Device Fabrication

Graphene’s properties that have positioned it as a strong candidate for optimizing photovoltaic devices include its lightness, transparency, large surface area, and lack of a bandgap due to its high mobility and electrical conductivity at room temperature.

Bandgap: energy barrier that electrons must overcome to flow as electrical current.

Over the years, graphene’s performance has been studied in interfacial layers, active layers, and as transparent conductive electrodes. Incorporating graphene into silicon solar cells can increase energy conversion efficiency by 20%; in perovskite graphene solar cells, higher current density and efficiency exceeding 80% have been observed. For dye-sensitized solar cells utilizing graphene oxide functionalized with titanium dioxide (TiO2), a plasmonic effect has been observed, demonstrating better light capture and charge transport efficiency.

Other examples of functionalizations tested on graphene include poly(3-hexylthiophene) (P3HT), gold nanoparticles, poly(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid), bis(trifluoromethanesulfonyl)amide, and metals like copper.

Graphene Functionalization for Lubricant Fabrication

In traditional synthetic oils, certain additives with nanoparticles are used to reduce energy loss and wear. This is justified by their ability to create protective films between the contact interfaces of rough surfaces, reducing friction and wear. However, a limitation for their use in lubricating oils, especially those with low viscosity, is the nanoparticles’ limited stability.

Graphene’s tribological or lubricating efficiency originates from its high mechanical strength, flat and thin structure with weak interlayer bonds, high thermal stability, and extensive surface area. Nevertheless, as in many other applications, graphene doping with nitrogen, phosphorus, sulfur, boron, and fluorine, or with alkyl groups like octadecylamine, octadecyltrichlorosilane, and octadecyltriethoxysilane, or modifications with amines such as alkylamines further improve its tribological properties. Additionally, polymer functionalization has shown good results not only for tribology but also for dispersion and stability, e.g., with polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), poly(ether-ether-ketone), and polyethyleneimine. Other studies have also reported functionalizations of graphene with octadecylamine for purposes such as lubricant biodegradability, among others.

The above describes only a few examples of the countless functionalizations that can be applied to graphene for specific applications. In many cases, the presence of graphene within a material or mixture is insufficient to generate a notable effect. Fortunately, its field of action is so broad that, when properly synthesized and utilized, it is possible to achieve astonishing results.

Written by: EF/DHS

  1. Surface Functionalization of Graphene-Based Materials: Biological Behavior, Toxicology, and Safe-By-Design Aspects , Adv. Biology 2021, 5, 2100637
  2. Applications of Pristine and Functionalized Carbon Nanotubes, Graphene, and Graphene Nanoribbons in Biomedicine. Nanomaterials 2021, 11, 3020
  3. Modelling of graphene functionalization, Phys. Chem. Chem. Phys., 2016, 18, 6351
  4. Graphene and functionalized graphene: Extraordinary prospects for nanobiocomposite materials . Composites Part B: Engineering, 2017, 121,34  
  5. Highly Stable Graphene Oxide-Gold Nanoparticle Platforms for Biosensing Applications, 2017,  Physical Chemistry Chemical Physics 20(3)
  6. Graphene oxide: a stable carbon framework for functionalization, : J. Mater. Chem. A, 2013, 1, 11559
  7. Functionalised graphene as flexible electrodes for polymer photovoltaics, Journal of Alloys and Compounds Volume 825, 5 June 2020, 153954
  8. Graphene and its derivatives for solar cells application, Nano Energy Volume 47, May 2018, Pages 51-65
  9. Effect of HNO3 functionalization on large scale graphene for enhanced tri-iodide reduction in dye-sensitized solar cells, journal of materials chemistry, 2012, 38
  10. The development of TiO2-graphene oxide nano composite thin films for solar cells, Results in Physics 11 (2018) 46
  11. Graphene/Si Schottky solar cells: a review of recent advances and prospects, RSC Adv., 2019, 9, 863–877 |
  12. Tribological improvement of potential lubricants for electric vehicles using double functionalized graphene oxide as additives, Tribology International 193 (2024) 109402
  13. Graphene-Based Nanomaterials as Lubricant Additives: A Review, Lubricants 2022, 10, 273

Graphene Aerogels

Posted on | by Energeia Graphenemex

Graphene Aerogels

A Revolution in Decontamination and Industrial Efficiency

Aerogels are synthetic, translucent materials with a gel-like appearance in which the liquid content is replaced with air or gas, creating a porous network of interconnected nanostructures. They are typically made from silica, alumina, chromium oxide, titanium, tin, or carbon, each offering specialized properties for different industries. For instance, in construction, they provide thermal and acoustic insulation; in food, they control moisture; in medicine, they release drugs and repair bone defects; in agriculture, they optimize water usage; and in environmental purification, they adsorb contaminants in water and air.

“Despite their advantages, aerogels face challenges such as fragility and high costs, prompting ongoing research to improve them.”

Graphene, a planar nanostructure consisting of one to ten layers of tightly bonded carbon atoms, boasts extraordinary mechanical, thermal, and electrical properties transferable to other materials. However, to ensure this transfer, graphene often undergoes additional functionalization with oxygen groups or chemical/physical dopants like DNA molecules, metallic ions, nanoparticles, or polymers. These modifications inhibit the π-π stacking of graphene layers, improving their interaction and stability—key challenges given graphene’s tendency to aggregate.

“A critical factor for graphene’s performance is the proper dispersion and distribution of its layers throughout the host material matrix.”

The intersection of aerogels and graphene lies in the fact that aerogels provide a three-dimensional macroscopic structure where graphene can remain stable without aggregating. Additionally, graphene enhances aerogel properties, such as lightweight construction, electrical conductivity, thermal insulation, compressibility, and elasticity. It also allows functionalization with other materials like cobalt hydroxide, cobalt oxide, manganese dioxide, molybdenum oxide, molybdenum disulfide, nitrogen, sulfur, or boron to improve electrochemical detection performance, supercapacitor efficiency, electrocatalytic functions, or contaminant adsorption.

Graphene Aerogels for Decontamination:

Graphene’s adsorbent capabilities are well-documented, particularly in its oxidized form, graphene oxide (GO), which offers a large surface area and numerous interaction sites for capturing pollutants. However, challenges such as the difficulty of removing adsorbed substances and recycling GO sheets limit practical applications. Recent advancements suggest that three-dimensional graphene aerogels effectively prevent GO aggregation during adsorption and enhance regeneration capabilities. These new structures, with their extremely low density, high porosity, and large surface area, facilitate contaminant diffusion and adsorption within the 3D network while enabling recyclability.

A 2024 study published in the renowned journal Nature detailed two methods for producing graphene aerogels. This research evaluated the photocatalytic capacity of both materials, finding superior performance compared to non-graphene counterparts. The study also analyzed various toxic organic solvents, pigments, and oils, such as formaldehyde, dichloromethane, acetone, ethanol, methanol, pump oil, castor oil, and silicone oil, achieving higher decontamination rates. Additionally, graphene aerogels have been shown to remove up to 99% of heavy metals from water, outperforming conventional adsorbents like activated carbon and other treatment methods like ion exchange, coagulation, and filtration. These advantages stem from their larger surface area, higher adsorption capacity, longer lifespan, and regenerative properties.

In air decontamination, most systems use high-efficiency particulate air (HEPA) filters with activated carbon. However, their limited adsorption capacity necessitates frequent maintenance and filter replacements. Addressing this issue, a study by Tianjin University in China explored the photocatalytic capability of titanium dioxide combined with the adsorption capacity of graphene aerogels. The research concluded that the synergy between these materials offers significant advantages over conventional filtration systems.

This demonstrates how two distinct technologies can merge to create synergies and address various challenges. For Energeia-Graphenemex, a leading Latin American company in graphene material production and application development, it is inspiring to see how graphene technology is gradually making a positive impact across different industrial sectors.

Authored by: EF/DHS

References:

  1. Gaelle Nassar, et. al., A review on the current research on graphene-based aerogels and their applications. Carbon Trends 4 (2021) 100065;
  2. Ting Yao et. al., Preparation of β-cyclodextrin-reduced graphene oxide aerogel and its application for adsorption of herbicides. Journal of Cleaner Production, 468, (2024) 143109;
  3. Karabo G. Sekwele et. al., Cellulose, graphene and graphene‑cellulose composite aerogels and their application in water treatment: a review. Discover Materials (2024) 4:23;
  4. Ashish K. Kasar et al., Graphene aerogel and its composites: synthesis, properties and applications. Journal of Porous Materials (2022) 29:1011

Carbonation and Graphene Oxide:

Posted on | by Energeia Graphenemex

Carbonation and Graphene Oxide:

A Solution for Reducing CO₂ Emissions

In previous articles, we discussed the cement industry’s impact on CO₂ emissions and the commitments made to reduce them by 2050. Today, we explore how carbonation—a process generally seen as a concrete pathology—could help offset some CO₂ emissions from cement production.

What is Carbonation?

In concrete, carbonation is a natural process where CO₂ from the environment reacts with moisture in the concrete, converting the alkaline calcium hydroxide in cement paste to calcium carbonate with a more neutral pH. This reaction lowers the concrete’s pH from around 12–13 to approximately 9, exposing steel reinforcements to corrosion.

What Affects Carbonation?

Carbonation rate depends on the diffusion of CO₂ and its reactivity with the cement matrix, which is in turn influenced by the matrix’s microstructure, hydration products (calcium hydroxide, calcium silicate hydrate, alkaline oxides, etc.), and pore structure (distribution, size, and saturation). Therefore, carbonation proceeds more slowly in low-permeability or dry concretes than in permeable ones with 50–60% humidity. To reduce porosity and calcium hydroxide levels, micrometric additives like fly ash, blast furnace slag, metakaolin, silica fume, and some nanomaterials are used during concrete production, alongside practices like applying surface coatings.

Carbonation as an Emission Reduction Tool

Carbonation can be viewed in two ways: first, as a concrete pathology, and second, as a CO₂-reducing opportunity. There are two types of carbonation: natural and accelerated. Natural carbonation is slow and does not capture CO₂, while accelerated (or mineral) carbonation uses high CO₂ concentrations, speeding up cement hydration and producing carbonates in which CO₂ is permanently stored in a thermodynamically stable mineral form. This process, known as recarbonation, involves the same carbonate used as a raw material in cement production. Companies like Blue Planet, Carbon Cure, Solidia Technologies, and Carbi Crete are developing strategies to sequester up to 17 kg of CO₂ per cubic meter of prefabricated concrete, as this process requires controlled conditions.

Graphene Oxide (GO) and Its Impact

Graphene oxide (GO) is a carbon nanostructure whose multifunctionality offers numerous benefits across industries. In concrete, GO enhances mechanical strength and durability, though its effects on carbonation and CO₂ capture are less well-documented.

Research conducted by the University of Arlington, Texas, in 2022 examined GO’s interaction mechanism in concrete cured under accelerated carbonation. Results indicated that GO, by improving cement hydration, refines concrete pores with calcium carbonate precipitated on hydration products and cement particles, limiting chemical reactions between hydration products and CO₂ under continuous CO₂ flow. The study concluded that GO not only enhances concrete’s mechanical properties but also helps capture and store up to 30% of atmospheric CO₂ during early curing stages.

Authored by: EF/ DHS

References

  1. Geetika Mishra, et al., Carbon sequestration in graphene oxide modified cementitious system, Journal of Building Engineering, 2022, 62, 105356;
  2. Nur Azni Farhana Mazri et al., Graphene and its tailoring as emerging 2D nanomaterials in efficient CO2 absorption: A state-of-the-art interpretative review. Alexandria Engineering Journal, 2023, 77, 479;
  3. Mohd Hanifa et al., A review on CO2 capture and sequestration in the construction industry: Emerging approaches and commercialised technologies, Journal of CO2 Utilization, 2023, 67, 102292;
  4. Yating Ye et al., Optimizing the Properties of Hybrids Based on Graphene Oxide forCarbon Dioxide Capture, Ind. Eng. Chem. Res. 2022, 61, 1332;
  5. Sanglakpam Chiranjiakumari Devi et al., Influence of graphene oxide on sulfate attack and carbonation of concrete containing recycled concrete aggregate, Construction and Building Materials, 2020, 250, 118883

Advances in Fire Protection:

Posted on | by Energeia Graphenemex

Advances in Fire Protection:

The Promise of Graphene Oxide in Intumescent Coatings

Intumescent coatings are specialized paints applied to concrete and steel structures in industrial and residential buildings to offer fire protection. They provide safety by allowing enough time for evacuation and assistance in the event of a fire.

During a fire, these coatings expand and form a carbonized foam that isolates the fire and limits its spread, while simultaneously releasing non-combustible gases that reduce the oxygen concentration around the structures, protecting them from significant damage for approximately 1 to 3 hours.

The main components of intumescent coatings are a polymeric binder, an acid source (e.g., ammonium polyphosphate – APP), an expansion additive (e.g., melamine – MEL), a carbon source (e.g., pentaerythritol – PER), and other filler elements (e.g., expandable graphite), which often influence the expansion factor and fire retardancy.

Despite their efficiency, the carbonized foam formed by the APP-MEL-PER system may have poor oxidation resistance at high temperatures, leading to lower fire-retardant efficiency and easier destruction during combustion. Therefore, other additives such as calcium carbonate, aluminum hydroxide, silica, and certain carbon materials have been explored to enhance their protection. For example, expandable graphite in epoxy coatings improves thermal degradation and fire resistance; carbon nanotubes reduce the heat release rate in polymers, and graphene oxide (GO), thanks to its reticular nanostructure, has been identified as an effective thermal barrier to prevent flame diffusion and reduce heat propagation. This occurs because GO, when evenly dispersed within the coating matrix, forms a “tortuous path” that reduces the thermal diffusion rate and matrix decomposition, thus improving fire resistance and mechanical strength.

Although no intumescent coatings with graphene oxide are currently on the market, research has shown that GO can improve the APP-MEL-PER system by promoting the decomposition reaction of APP, which accelerates the formation of phosphoric acid that reacts with PER to form carbon. While it has been observed that GO may slightly decrease the thermal stability of coatings, its presence encourages gas production and intumescent coefficients, reducing thermal conductivity.

Energeia-Graphenemex®, in collaboration with a renowned Mexican specialized coatings company, is working on a new development to launch the first intumescent coating with graphene oxide to continue placing Mexico at the forefront of new technologies.

Authored by: EF/DHS

References:

  1. Wang Zhan et al., Influence of graphene on fire protection of intumescent fire retardant

coating for steel structure, Energy Reports 6 (2020) 693;

  • Qiuchen Zhang et al., Effects and Mechanisms of Ultralow Concentrations of Different Types of Graphene Oxide Flakes on Fire Resistance of Water-Based Intumescent Coatings, Coatings 2024, 14, 162;
  • M. Sabet, et al., The Effect of Graphene Oxide on Flame Retardancy of Polypropylene and Polystyrene, Materials Performance and Characterization 9, no. 1 (2020): 284;
  • Cheng‑Fei Cao et al., Fire Intumescent, High‑Temperature Resistant, Mechanically Flexible Graphene Oxide Network for Exceptional Fire Shielding and Ultra‑Fast Fire Warning, Nano-Micro Lett. (2022) 14:92;
  • Quanyi Liu et al., Recent advances in the flame retardancy role of graphene and its derivatives in epoxy resin materials. Composites Part A: Applied Science and Manufacturing, 2021, 149, 106539

The Impact of Graphene on the Plastic Industry:

Posted on | by Energeia Graphenemex

The Impact of Graphene on the Plastic Industry:

Innovation and Sustainability

The origins of plastic trace back to 1860 in the United States when Phelan & Collander, amid an ivory shortage—a material widely used for billiard balls, piano keys, jewelry, and decorative structures—announced a call for a material capable of replacing ivory, offering substantial financial compensation for the time. John Wesley Hyatt proposed “celluloid,” a plant-based carbohydrate that, while not fully replacing ivory, became the stepping stone for the development of plastic, with immediate successors like Bakelite and PVC leading to today’s engineering plastics.

The term “plastic” comes from the Greek “plastikos,” meaning “moldable.”

Plastics are synthetic materials obtained through various polymerization processes from petroleum derivatives. Their evolution and refinement have made them essential to numerous industries and activities. However, after years of unchecked use, plastics have become both a solution for many needs and a significant environmental and health issue, as their versatility and demand have also led to increased waste. As a result, the not-so-new philosophy of sustainable circularity, or the circular economy, involves not only awareness of resource use but also economic, infrastructure, and recycling process adaptations.

Recycling involves reprocessing used materials, such as plastics, for reuse. While an excellent tool for preserving natural resources and reducing waste, two key points must be considered. First, recycling doesn’t apply in all cases because not all plastics are recyclable. Second, reprocessing involves stages where materials may lose properties compared to virgin plastics, limiting their use in many industrial applications.

Over the past 20 years, nanotechnology’s intervention in modifying polymers like polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), among others, with carbon nanoparticles like graphene or carbon nanotubes (CNTs), has yielded interesting results regarding improved mechanical, rheological, electrical, and thermal properties. Graphene’s advantage over CNTs, in addition to other intrinsic properties, lies in its sheet-like structure, whose large surface area and greater dispersibility allow it to create more homogeneous phases, improving load transfer and thereby increasing the mechanical strength of modified plastics.

Companies such as Gerdau Graphene (Brazil), Graphenetech S.L. (Spain), Colloids (UK), and Energeia-Graphenemex (Mexico) have positioned various types of graphene-based masterbatches or concentrated plastics in the market over the past five years. Although each company has its own objectives and markets, there are environmental and economic points of convergence that motivated them to improve the plastic industry. Graphene, even in low concentrations (< 2% by weight), can enhance the quality of both virgin and recycled polymers. For example, graphene can increase flexural modulus by 30%, impact resistance by 40%, tensile strength by 17%, and resistance to rupture by 60%. It can also improve resistance to photodegradation. Depending on the specific needs of each development or application, it is possible to restore some of the mechanical properties of recycled plastics and/or extend the material’s lifespan to reduce the circulation of single-use plastics or, alternatively, achieve the same mechanical properties of polymers with reduced thickness.

Energeia – Graphenemex®, the leading Mexican company in Latin America in graphene material research and production for industrial applications, launched a wide range of graphene-based masterbatches in 2023 through its Graphenergy Masterbatch line, designed to be used as multifunctional reinforcement additives. Key advantages include:

  • Excellent dispersion within the polymer matrix
  • Can be incorporated into recycled polymers
  • Increase tensile, deformation, and impact resistance
  • Improve resistance to ultraviolet rays
  • Facilitate processing conditions (thermal stability)
  • Act as nucleating agents (modify polymer crystallization temperature).

Drafting: EF/DHS

References:

  1. Ramazan Asmatulu et al., Synthesis and Analysis of Injection-Molded Nanocomposites of Recycled High-Density Polyethylene Incorporated With Graphene Nanoflakes, POLYMER COMPOSITES—2015;
  2. Feras Korkees et al., Functionalised graphene effect on the mechanical and thermal properties of recycled PA6/PA6,6 blends. 2021 Journal of Composite Materials 55(16);
  3. Devinda Wijerathne et. al., Mechanical and graphe properties of graphene nanoplatelets-reinforced recycled polycarbonate composites. International Journal of Lightweight Materials and Manufacture 6 (2023) 117e128;
  4. Abdou Khadri Diallo et al., A multifunctional additive for sustainability, Sustainable Materials and Technologies, 33, 2022, e000487.

Innovation with Graphene

Posted on | by Energeia Graphenemex

Innovation with Graphene:

Towards a More Sustainable and Efficient Cement Industry

Part 1

Carbon dioxide (CO2) is a colorless, odorless, and non-toxic gas naturally present in the atmosphere. Under normal conditions, it should remain balanced to retain the heat necessary for human survival without becoming a greenhouse gas. However, overpopulation, industrialization, and environmental exploitation have disrupted this balance, making CO2 levels increasingly difficult to control. Consequently, these levels rise, concentrate, absorb radiation, and prevent heat from escaping, contributing to global warming.

According to statistics, cement production and the fossil fuel industry (coal, oil, and natural gas) are responsible for releasing about 90% of CO2 and probably 70% of greenhouse gases. Other industries, such as agriculture, fashion, and transportation, also contribute.

“Sustainability of our civilization depends on whether we can provide energy, food, and chemicals to the growing population without compromising the long-term health of our planet.” Doria-Serrano, 2009.

Concerning cement, the main component of concrete, reports mention that it alone accounts for between 7% and 8% of global CO2 emissions. For reference, producing one ton of clinker, the main component of cement, releases approximately ~0.86 tons of CO2, of which around 60% comes from the transformation of limestone into calcium oxide or lime at an average temperature of 1450 °C, a process also known as clinker burning. The remaining 40% is attributed to the combustion of fossil fuel (coal) necessary for the calcination of limestone and clinker formation.

“In 2021, carbon emissions from cement production reached nearly 2,900 million tons of carbon dioxide, while in 2002, 1,400 million tons were recorded.” The Global Carbon Project.

Therefore, to achieve the net-zero emissions target by 2050 required by the Paris Agreement, the cement industry has been forced to take measures to reduce its impact by using alternative fuels (biomass, tires, urban solid waste); improving energy efficiency by reducing the clinkerization temperature through fluxes and mineralizers (such as CaF2, BaO, SnO2, P2O5, Na2O, NiO, ZnO, etc.) or by renewing kilns; modifying cement chemistry with supplementary materials to reduce clinker consumption or capture CO2; and, recently, using graphene to improve the quality of cement and concrete.

“By 2050, global concrete consumption is expected to increase by 12% to 23% from 25 billion per year.”

According to the National Cement Chamber (CANACEM), most projects registered in Latin America are working on replacing fossil fuels with alternative fuels; Mexico is the only country registering higher production of blended cements to reduce clinker content.

Graphene is a nanomaterial consisting of atomic carbon sheets separated from graphite, with mechanical, electrical, thermal, and barrier properties superior to other carbon-based materials, allowing it to venture into countless applications and industries, including construction. According to estimates by Graphene Flagship, the use of graphene in construction is expected to reduce CO2 emissions by 30%.

“The production of 1 kg of graphene produces 0.17 kg of CO2, compared to 0.86 kg of CO2 for Portland cement, reinforcing the nanomaterial’s environmental advantages.”

Since the isolation of graphene in 2004 and the subsequent Nobel Prize in Physics 2010 awarded to its discoverers, an international race began to study, understand, and obtain the nanomaterial in sufficient quantities for large-scale applications at an affordable cost. In the construction sector, it was not until 2018 that research and investments manifested their first results in various parts of the world, such as:

2018: Graphenemex® launched Nanocreto®, the world’s first graphene oxide concrete additive (Mexico).

2019: Graphenenano developed Smart additives, graphene additives for concrete (Spain).

2019: GrapheneCA presented its OG concrete admix product line for the concrete industry (USA).

2021: Scientists at the University of Manchester developed the Concretene concrete additive (UK).

2022: Energeia Fusion-Graphenemex® launched the Graphenergy construction line, an improved version of Nanocreto® (Mexico).

2022: Versarien presented Cementene™, the world’s first 3D-printed construction with a graphene-reinforced mix (UK).

Basquiroto de Souza and collaborators, in their article “Graphene opens pathways to a carbon-neutral cement industry” published in 2022 in Science Bulletin, summarized the opportunities that graphene has for the sustainability of construction materials:

Reduction of Portland cement thanks to significant improvements in compressive strength and elastic modulus of concrete.

Increase the use of by-products or recycled materials in concrete to reduce greenhouse gas emissions by up to 7%, as well as a 2% reduction in energy consumption during the manufacture of graphene oxide reinforced mortar.

Reduction in construction costs due to improved strength or greater incorporation of by-products or waste materials. A cost analysis concluded that while the use of graphene oxide may slightly increase concrete costs, the economy index (compressive strength/cost per m3) of the mixes can increase by up to 40%.

Reduction in maintenance costs. By improving the quality of concrete structures, reductions in CO2 emissions are inferred through a reduction in the amount of construction materials and energy associated with maintenance.

Energy-efficient buildings: graphene’s thermal properties can also be applied to buildings to achieve energy savings by reducing the use of cooling/heating systems.

For Energeia-Graphenemex®, the leading company in Latin America in designing applications with graphene materials, it is a pride to be part of the graphene timeline for sustainable construction.

Authored by: EF/DHS

References

  1. Ige, O.E.; Olanrewaju, O.A.; Duffy, K.J.; Collins, O.C. Environmental Impact Analysis of Portland Cement (CEM1) Using the Midpoint Method. Energies 2022, 15, 2708.
  2. International Energy Agency, World Business Council for Sustainable Development. Technology roadmap – low-carbon transition in the cement industry. April 2018
  3. Felipe Basquiroto de Souza, Xupei Yao, Wenchao Gao, Wenhui Duan, Graphene opens pathways to a carbon-neutral cement industry, Science Bulletin, 2022, 67, 1, 2022, 5
  4. Papanikolaou I, Arena N, Al-Tabbaa A. Graphene nanoplatelet reinforced concrete for self-sensing structures– a lifecycle assessment perspective. Journal of Cleaner Production, 2019, 240: 118202
  5. Devi S, Khan R. Effect of graphene oxide on mechanical and durability performance of concrete. Journal of Building Engineering, 2020, 27: 101007
  6. Doria- Serrano. Química verde: un nuevo enfoque para el cuidado del medio ambiente. Educación química. 2009. UNAM.
  7. https://theplanetapp.com/que-son-las-emisiones-de-co2/
  8. https://graphene-flagship.eu/materials/news/materials-of-the-future-graphene-and-concrete/#:~:text=Graphene%2Denhanced%20concrete%20is%202.5,CO2%20emissions%20by%2030%25.
  9. https://www.versarien.com/files/5716/3050/8952/White_Paper_-_Graphene_for_the_construction_sector_-_final_version.pdf

Innovation in Non-Stick Coatings

Posted on | by Energeia Graphenemex

Innovation in Non-Stick Coatings:

Integration of Graphene Materials for Enhanced Properties and Performance

Currently, non-stick coatings refer to coatings that, to some extent, prevent the adhesion of substances, whether solid or liquid, to the surface they are applied on. The non-stick capability of these coatings is based on their very low surface tension, also known as surface energy, represented by “γ”.

For coatings to be considered non-stick, they must have a surface energy, γ, less than 26 mJ/m² and water contact angles greater than 90°. A surface where the drop forms a contact angle greater than 90° is a hydrophobic surface. This condition implies low wettability, adhesiveness, and surface energy (see Fig. 1). In contrast, if the surface is hydrophilic, a contact angle less than 90° will be observed, and the wettability, adhesiveness, and surface energy will be high.

Fig. 1 Scheme representing the contact angles of a hydrophobic and hydrophilic surface.

Industrially, there are multiple non-stick coatings based on fluoropolymers. The uses and applications of fluoropolymers in coatings cover a wide range of products. The non-stick effect and easy demolding allow their use in various industries, such as textile, chemical, automotive, and food industries, for the production of utensils, molds, tools, and equipment that need to be isolated from chemicals or food.

Most non-stick coatings have high thermal resistance; however, they do not have great abrasion resistance. The use of fluoropolymers in kitchen utensils raises concerns about the potential health risks, as harmful substances might be released during use.

In recent years, Energeia – Graphenemex®, a Mexican company leading in graphene material production, has implemented the use of these carbon-based nanomaterials. Graphene materials, such as graphene oxide and graphene, enhance properties in coatings, for example, anticorrosive, antibacterial, greater abrasion resistance, and high UV resistance.

During these property evaluations, it was observed that graphene materials can also be used as new additives for developing non-stick coatings. Incorporating graphene materials into epoxy-type coatings improved substrate adhesion; however, the finish of these coatings was smoother and shinier. When exposed to a corrosive environment, the coating showed hydrophobic behavior, keeping its surface cleaner compared to the control coating (without graphene material), which gradually lost its shine and showed wettability and contaminant deposition on the coating surface (see Fig. 2).

Fig. 2 Non-stick effects of coatings with graphene material.

Furthermore, the non-stick effect of an ecological coating with and without graphene material was evaluated. This coating is made of lime, nopal mucilage, and mineral pigments. It is well known that lime and carbonate-based materials absorb moisture easily, so the effect of graphene material in lime-based paint was studied. The results showed that the paint had an antimicrobial effect, greater UV resistance, and higher impermeability (non-stick effect).

In Fig. 3, the response of a lime-based coating with and without graphene material, when wetted by water, is shown. The coatings with graphene materials (Graphene and graphene oxide (GO)) at different concentrations showed very little deformation in the drop as its internal energy was higher than the surface energy, displaying hydrophobic behavior (water repellency). In the case of the control coating (without graphene material), it was observed to have very little non-stick capacity, absorbing water more easily due to high surface energy. The drop spread on the surface immediately when the water drop fell on the surface, showing highly hydrophilic behavior. These results showed that graphene materials modified the nature of the coating, i.e., they modified the surface energy of the coatings at the surface level.

Fig. 3 Wetting behavior of a lime-based coating, with and without graphene materials.

Currently, Energeia – Graphenemex®, a leading Mexican company in Latin America in the research and production of graphene materials for industrial application development, offers various types of graphene materials for use in developing and producing anticorrosive, antibacterial, and enhanced non-stick coatings.

References

  1. Tong, Yao &Song, Mo. (2013). Graphene based materials and their composites as coatings.
  2. Zhen, Z. & Zhu, H. Graphene: Fabrication, Characterizations, Properties and Applications. Graphene (Academic Press, 2018).
  3. Sachin Sharma Ashok Kumar, Shahid Bashir, K. Ramesh, S. Ramesh, Progress in Organic Coatings, 154, (2021)

Graphene Oxide Versatile Applications

Posted on | by Energeia Graphenemex

Graphene Oxide Versatile Applications:

From Sensing Technologies to Environmental Solutions

Graphene and its derivatives such as graphene oxide (GO) and reduced graphene oxide (rGO) are two-dimensional, sheet-like carbon nanomaterials with a wide range of opportunities for numerous applications due to their thinness, transparency, conductivity, flexibility, chemical stability, impermeability, and mechanical strength. In the case of GO and rGO, in addition to their large surface area with hydrophilic and hydrophobic regions inherent to graphene, they allow the adsorption of organic aromatic molecules, ions, and polymers through π-π stacking, hydrogen bonding, and electrostatic interactions. These properties make them suitable materials for constructing sensors or biocatalytic and photocatalytic platforms. According to various reports, the surface-to-volume ratio of graphene materials enhances the surface charge of the desired molecules, while their excellent electrical conductivity, especially at room temperature, favors electron transfer to the surface of electrodes for analysis or photocatalysis.

On the other hand, graphene sheets are not perfectly flat; they exhibit undulations formed as a result of the bonding between their carbon atoms or thermal fluctuations, which can ultimately induce magnetic fields and alter their electronic properties for designing sensors, biosensors, or electronic devices in general. Thus, through more than ten years of research and exploration of their remarkable multifunctionality, the study of graphene has transcended to the development of highly sensitive devices for monitoring, for example, the presence of harmful gases, medically relevant molecules, or proteins, and even water decontamination.

Detection Systems

Metamaterials are a type of compound with the ability to produce useful electromagnetic responses for designing sensors or non-destructive detection devices. Generally, these sensors consist of an insulating material and a conductive material, sensitive to the refractive index of the analyte’s upper layer. In the presence of graphene, it has been observed that this interaction (sensor-analyte) is enhanced by changes in resonance intensity, leading to amplitude changes that further favor detection sensitivity.

In a study conducted in 2023 by the School of Electronic and Information Engineering at Zhejiang University of Science and Technology, Hangzhou, China, a sensor was designed comprising a polyimide (PI) film as an insulating layer, an aluminum structure as a conductive layer, and a monolayer of graphene as the detection interface. Simulation results indicated that graphene could modulate the entire electric field and produce an amplitude change that significantly increases detection limits.

In another study conducted at the Laboratory of Nanostructured Materials of the Institute of Physics at UASLP, functionalized graphene oxide with gold nanoparticles was used as a SERS (Surface Enhanced Raman spectroscopy) biodetection platform, an important technique for biological detection due to its high sensitivity, low sample requirements, relatively low cost, and real-time detection. Crystal violet was used as the standard molecule and flavin adenine dinucleotide as the experimental coenzyme for its participation in numerous redox processes of metabolic reactions and biological electron transport. The results showed that graphene oxide hybrids with gold nanoparticles substantially enhance SERS signals compared to individual nanoparticles. Additionally, the results are consistent with other research on identifying significant improvements for molecule stabilization and fluorescence reduction during measurements, which is often a major drawback of such techniques, supporting its potential as a diagnostic or monitoring tool.

Toxic Gas Removal

Advances in nanoengineering allow graphene and GO sheets to be manipulated for the detection and separation of certain gases. According to the results of a study conducted by the Department of Energy Engineering at Hanyang University, Seoul, Korea, selective diffusion can be achieved by controlling the gas flow channels and pores through different stacking methods, demonstrating that GO’s functional groups provide a unique adsorption behavior towards CO2.

CO2 Conversion

The photocatalytic properties of GO can also be harnessed for converting CO2 into hydrocarbons such as methanol for solar energy capture and CO2 reduction. In 2018, at the Advanced Technology Laboratory for Materials Synthesis and Processing, Wuhan University of Technology, China, silver chromate (Ag2CrO4) nanoparticles were used as a photosensitizer and GO as a co-catalyst for the photocatalytic reduction of CO2 into methanol and methane. The study concluded that this synergy between nanoparticles could enhance conversion activity up to 2.3 times under solar irradiation due to better light absorption, increased CO2 adsorption, and improved charge separation efficiency.

Water Decontamination

Water technologies have various areas of opportunity, particularly in improving filtration or membrane systems. In this regard, it has been found that using hybrid graphene nanostructures, for example, with ruthenium or magnetite, can allow the removal of microorganisms and organic matter present in water. However, research continues to advance to perfect graphene-based methodologies for the removal and reduction of metal ions such as zinc, copper, lead, cadmium, cobalt, among others.

At Energeia-Graphenemex®, we recognize and admire the advancements that research centers have achieved in various areas of knowledge, starting from basic science to applied science results. We firmly believe that in the short or medium term, these technologies will materialize into real products that are useful to society and the environment.

Redaction: EF/ DHS   

References

  1. A. Fasolino, J.H. Los, M.I. Katsnelson, Intrinsic ripples in graphene, Nat. Mater. 6 (2007) 858;
  2. W. Bao, F. Miao, Z. Chen, H. Zhang, W. Jang, C. Dames, C.N. Lau, Controlled ripple texturing of suspended graphene and ultrathin graphite membranes, Nat. Nanotechnol. 4 (2009) 562; 3. G. Yildiz, M. Bolton-Warberg and F. Awaja. Graphene and graphene oxide for bio-sensing: General properties and the effects of graphene ripples. Acta Biomaterialia 131 (2021) 62;
  3. Lang, T.; Xiao, M.; Cen,W. Graphene-Based Metamaterial Sensor for Pesticide Trace Detection. Biosensors 2023, 13, 560;
  4. D. Hernández- Sánchez, E. G. Villabona Leal, I. Saucedo-Orozco, V. Bracamonte, E. Pérez, C. Bittencourt and M. Quintana, Phys. Chem. Chem. Phys., 2017;
  5. Kim, H.W.; Yoon, H.W.; Yoon, S.-M.; Yoo, B.M.; Ahn, B.K.; Cho, Y.H.; Shin, H.J.; Yang, H.; Paik, U.; Kwon, S. Selective gas transport through few-layered graphene and graphene oxide membranes. Science 2013, 342, 91;
  6. Kim, D.; Kim, D.W.; Lim, H.-K.; Jeon, J.; Kim, H.; Jung, H.-T.; Lee, H. Intercalation of gas molecules in graphene oxide interlayer: The role of water. J. Phys. Chem. C 2014, 118, 11142;
  7. Xu, D.; Cheng, B.; Wang, W.; Jiang, C.; Yu, J. Ag2CrO4/g-C3N4/graphene oxide ternary nanocomposite Z-scheme photocatalyst with enhanced CO2 reduction activity. Appl. Catal. B Environ. 2018, 231, 368;
  8. Jiˇríˇcková, A.; Jankovský, O.; Sofer, Z.; Sedmidubský, D. Synthesis and Applications of Graphene Oxide. Materials 2022, 15, 920;
  9. M. Quintana, E. Vazquez & M. Prato, “Organic Functionalization of Graphene in Dispersions”, Acc. Chem. Res., vol. 46, n.o 1, pp. 138-148, 2013. DOI: 10.1021/ar300138e;
  10. Roberto Urcuyo1,2,3, Diego González-Flores1,3, Karla Cordero-Solano, Rev. Colomb. Quim., vol. 50, no. 1, pp. 51-85, 2021;
  11. B. Xue, M. Qin, J. Wu et al., “Electroresponsive Supramolecular Graphene Oxide Hydrogels for Active Bacteria Adsorption and Removal”, ACS Appl. Mater. Interfaces, 8, 24, 15120;
  12. C. Wang, C. Feng, Y. Gao, X. Ma, Q. Wu & Z. Wang, “Preparation of a graphene-based magnetic nanocomposite for the removal of an organic dye from aqueous solution”, Chem. Eng. J.,173, 1, 92.

Advancing Asphalt Durability

Posted on | by Energeia Graphenemex

Advancing Asphalt Durability:

Harnessing Graphene’s Potential for Sustainable Roads

Most of the the world’s road infrastructure is composed of pavement made from a complex system of asphalt, aggregates, and binders that interact at an interface to maintain its strength and structural stability. According to the Asphalt Institute, 87 million tons of asphalt are produced worldwide annually, with around 85% used in the paving industry, which, while offering great load capacity and durability, inevitably suffers damage from constant exposure to radiation, temperature, humidity, and traffic.

The deterioration of asphalt not only impacts a basic transportation infrastructure crucial for socio-economic development but also involves environmental impacts in terms of resource depletion and high CO2 emissions caused by roadworks. These factors add to the reasons for the constant search for modification technologies that increase durability and improve mechanical properties of pavements using fibers, rubber; additives such as thermoplastic elastomers, plastic and synthetic resins, iron powder, hydrated lime, or glass waste. However, in some cases, the application of these products can present practical problems such as special preparation conditions, low storage stability, difficulty in mixing during construction, and complexity in compatibilizing these components with the asphalt system.

Fortunately, carbon nanostructures such as graphene and graphene oxide (GO) reappear on the scene as proposed solutions to these issues with interesting contributions to asphalt regarding stiffness, anti-aging, deformation, and penetration resistance; reduction in rutting, improved consistency, heat transfer capacity; skid resistance, and even a reduction in the effort required for compaction during preparation.

Additionally, among the advantages of graphene is its ability to be mixed with other asphalt modifying technologies such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), polyethylene terephthalate (PET), polystyrene (PS), granulated rubber, blast furnace slag, epoxy resins, and especially with styrene-butadiene-styrene (SBS), which is one of the most accepted polymers in the asphalt industry, and with which graphene oxide (GO), thanks to its oxygen content, promotes the absorption of aromatics and saturates from SBS with a significant improvement in temperature response, adhesion, and binder stiffness.

Some identified methods that promise to simplify the incorporation of graphene into asphalt mixes are:

  1. Direct addition method: graphene is added to the previously melted asphalt binder.
  2. Indirect addition method: graphene and asphalt binder are simultaneously dissolved in a medium solution to later form a uniform solution.
  3. Auxiliary addition method: graphene is chemically modified with functional groups or added together with other modifying agents to later melt into the asphalt binder.

Although there are few companies that have explored graphene as an asphalt improving additive so far, the extensive research conducted over the past decade is helping to lay the groundwork for understanding and projecting the potential of this technology for the benefit of the paving industry. Even in February 2024, the Infrastructure journal published the results of the ECOPAVE project funded by the European Union, which consisted of a 5-year field test conducted over 1 km of heavy traffic in southern Rome, Italy. For the study, four sections of asphalt pavement with and without additions of graphene-modified polymers were installed. After the 5-year evaluation period, researchers reaffirmed the potential of asphalt modified with graphene polymer as an innovative and feasible technology for high-traffic road paving, as it demonstrated higher stiffness values at different temperatures, better fatigue behavior, and greater deformation resistance, promising an extended lifespan with a significant reduction in maintenance costs.

At Energeia-Graphenemex®, as leaders in graphene application development, we firmly believe that, although there is still work to be done, we are very close to enjoying the economic and environmental benefits that this wonderful technology can bring not only to our streets and roads but also to society.

Draft: EF/DHS

References

  1. Mechanism and Performance of Graphene Modified Asphalt: An Experimental Approach Combined with Molecular Dynamic Simulations. Case Studies in Construction Materials. 2023, 18, e01749;
  2. Properties and Characterization Techniques of Graphene Modified Asphalt Binders. Nanomaterials 2023, 13, 955;
  3. Analysis on the road performance of graphene composite rubber asphalt and its mixture. Case Studies in Construction Materials. 2022, 17, e01664;
  4. A complete study on an asphalt concrete modified with Graphene and recycled hard-plastics: A case study. Case Studies in Construction Materials. 2022, 17, e01437;
  5. Effect of Graphene Oxide on Aging Properties of polyurethane-SBS Modified Asphalt and Asphalt Mixture. Polymers 2022, 14, 3496;
  6. Mechanical Characteristics of Graphene Nanoplatelets-Modified Asphalt Mixes: A Comparison with Polymer- and Not-Modified Asphalt Mixes. Materials 2021, 14, 2434;
  7. Impact of Graphene Oxide on Zero Shear Viscosity, Fatigue Life and Low-Temperature Properties of Asphalt Binder. Materials 2021, 14, 3073;
  8. Experimental Investigation into the Structural and Functional Performance of Graphene Nano-Platelet (GNP)-Doped Asphalt. Appl. Sci. 2019, 9, 686;
  9. Modified Asphalt with Graphene-Enhanced Polymeric Compound: A Case Study. Infrastructures 2024, 9, 39.