Carbon Composite Catalysts

Three-dimensional (3D) graphene architectures (hydrogel, aerogel, coke, foam, sponge) have become the preferred materials in many areas, especially in electronic applications. Graphene foams, which contain both graphene and 3D macroscopic material properties, provide many advantages for material science. These structures, which have concurrently high mechanical strength and flexibility, have offered the opportunity to be used in some electronic devices that require pressure application. Its lightweight is also proper for portable and wearable applications. Graphene foam composites with high electrical conductivity are often used as catalysts in different fields. By force of a 3D interconnected graphene network, the transfer of electrons and ions within the structure occurs in a facile way. The heteroatom (nitrogen (N), boron (B), phosphorus (P), sulfur (S)) doping to carbon materials has been one of the effective ways to modify the electronic and catalytic properties of the carbon host. In this chapter, some information on the synthesis and application areas of 3D N-doped graphene foam structures were presented. Graphene foams are synthesized and N-doped simultaneously with the chemical vapor deposition (CVD) method by a majority. The applications of the 3D N-doped graphene foams as carbon composite catalysts were evaluated in the fields of fuel cells, batteries, supercapacitors and other catalytic reactions. Additionally, other applications of 3D N-doped graphene foams were also briefly mentioned.

Carbon-based nanomaterials are widely used in the chemical industry, as catalysts or catalyst supports in energy and ecological applications, due to their different properties. High surface areas, porosity, sizes and shapes are considered important because they increase the catalytic performance of carbon-based materials. Especially graphene and carbon nanotube-based nanocomposites from carbon-based materials have shown exceptional catalytic activity in organic reactions. It has been observed that catalytic products prepared using carbon nanocomposites are very important in many fields including medicine, biomedical, agricultural and material sciences. Therefore, the demand for carbon nanocomposites is increasing rapidly. The development of new preparation methods and the increase in application areas make this subject special. In this section, researches on the types, preparation methods and application areas of carbon-based nanocomposite materials in recent years were carried out.

Recently, perovskite materials have shown excellent promise for efficient photodegradation and water splitting processes, on account of their unique crystal structure and electronic properties. The crystal structure of perovskite offers an excellent framework to tune the band gap values to enable visible light absorption and band edge potentials, meeting the requirement of specific photocatalytic features. Nevertheless, fast recombination rate, long-term stability as well as large-scale production still limit their applications especially in light driven processes. Carbon materials, scoping from one-dimensional nanostructures to three-dimensional carbon aerogels, have been successfully utilized in improving structural and optical properties as well as catalytic activities of perovskites. In particular, the recombination rates can be remarkably hindered with the introduction of carbon materials upgrading the catalytic degradation performance. Various perovskite-carbon composites have been discussed, emphasizing their synthesis method, specific improvements on their characteristics related with enhanced activities in the photocatalytic-driven systems. This review provides a broad overview of perovskite coupled with carbonaceous photocatalysts, summarizing developments, and offering useful insights for their future studies.

There is a growing interest for the development of various kind of catalysts to overcome the sluggish kinetics reaction of ORR at the cathode. Therefore, a lot of research have been done to search for promising catalysts that can speed up the ORR kinetics, hence enhance the performance. Carbon-based materials such as carbon black, carbon nanotube, and graphene derivatives hold the greatest promise as potentially ideal alternatives for ORR electrocatalyst owing to their abundance, low-cost, high surface area, and outstanding electronic conductivity. This chapter mainly focuses on research interest and activity on carbon composite catalysts for ORR, including hybridization with platinum group metal (PGM) and non-PGM. The role of carbon-based materials as support in the composite has also been discussed. Additionally, heteroatom-doping carbon composite catalyst was highlighted with an aim to enhance the catalytic performance by altering the electronic properties of carbon. To assist readers, we first provide an overview of the following background information of ORR, the reaction pathway, and the role of electrocatalyst in ORR, respectively.

In recent years, carbon-based metal-free composites have come to the fore with their superior properties. Carbon-based materials attract the attention of researchers with porous structure, high surface areas, catalytic activity, high selectivity, thermal stability, mechanical strength, and chemical stability. Surface areas of these materials can be developed by functionalizing with various groups. They are widely used with these features in many fields such as electronics, energy, and materials science. In addition, they are preferred as an adsorbent as they provide high adsorption efficiency for heavy metal and dye removal from wastewater. In this study, recent studies in which carbon-based materials are used in hydrogen production and solar cell systems as catalysts have been investigated. The carbon-based materials used as adsorbents have been also researched and compared.

Detail study has been focused on carbon nanotubes-based mixed matrix membranes (MMMs) in separation technology. The MMMs due to possessing significant properties such as high permeability, acceptable selectivity, enough flexibility, etc. have been considered as good candidate for the separation purposes. These properties are attributed to the presence and synergistic effects of three independent phases including organic, inorganic and filler ones with adequate and compatible work function. Consequently, the MMMs have great applications in different parts of science, especially at the separation field. Also about the carbon-nanotube-based MMMs, presence of multiple basal/edge planes in their matrices make them appropriate support with enough active surface area and plenty of O–H and –COOH functional groups. In this book chapter the MMMs have been evaluated from some different experimental and modeling aspects and have been introduced based on the researches published on the academic journals during the last decades. To the best of knowledge, there is no reports on the application of MMM in the separation science.

Nanoscience and nanotechnology have revolutionized organic catalysis, increasing the efficiency of these reactions and reducing their environmental impact. Particularly, carbon nanotubes are widely used in many organic reactions such as C–C couplings, hydrogenations, alkane dehydrogenations, transesterifications and oxidations. Excellent results have been obtained in terms of the synthesis of the catalysts, reaction yields, selectivity, and reusability. In this review, we provide a general overview of the design, synthesis, and use of carbon nanotubes as catalysts and catalytic supports, along with the main strategies for their surface functionalization and doping with heteroatoms. Concluding considerations from the authors’ perspective are provided, regarding the promising use of these materials and the challenges to be faced in the near future.

The DMFC commercialization and practical operations are still confronts several major challenges particularly in high cost, maintaining long-term stability and durability, deteriorating of anode electrocatalyst performance as well as the sluggish methanol oxidation kinetic reaction occurred at the anode due to the poisoning effect of the platinum (Pt) electrocatalyst. The selection of the appropriate anode electrocatalysts for methanol oxidation reaction (MOR) is quite limited, only the anode electrocatalysts that can enhance the MOR activity and minimize the poisoning effect by the carbonaceous intermediate species-like carbon monoxide (CO) can be considered to improve the DMFC performance. The strategy of coupling or alloying Pt with other noble or non-noble metals can prevent such mentioned problems above and able to upgrade the ability of anti-CO poisoning through the modification of the CO adsorption site. In general, the highly accessible of electrocatalytic active sites and dispersed are very important for the superior Pt-based alloy electrocatalyst performance through the utilization of the electrocatalyst support with the large specific surface areas. However, the commonly used carbon supporting materials for monometallic Pt and bimetallic Pt-based alloy electrocatalysts suffer from severe corrosion due to the electrooxidation on the surface under acidic condition at high operating voltages for prolonged times which resulting the dissolution, aggregation, migration and detachment of Pt NPs leading to a serious problem of stability. The most efficient strategy to overcome the limitations described above is through the embedding the monometallic Pt and bimetallic Pt-based alloy electrocatalyst on the metal oxides. This proposed strategy provides a medium to anchor the Pt-based alloy electrocatalyst securely onto the carbonaceous support materials and the electrocatalytic performance of the electrocatalyst also have been proven to be significantly improved in oxidizing the methanol in DMFC. Nevertheless, studies on the possible combination of both supported Pt-based alloy electrocatalyst embedding metal oxides as the potential anode nanocomposite electrocatalyst with careful design still lacking and remains important challenge.

This chapter discusses hybrid composites, which comprise a carbonaceous matrix material (amorphous carbon, activated carbon, biochar, hydrochar, polymeric carbon, graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, and fullerenes) that serve as a support and/or or anchor of a photocatalyst. Each composite component contributes to the catalytic performance and the mechanism for these good effects is the key point, and these effects can be: Single support effect, stabilization of microstructure or active components, dual function effect on pollutant degradation reactions, influence in the speed of adsorption/desorption and diffusion of molecules, influences the migration or transfer of active free radical species (O₂-•, h⁺, •OH, 1O₂), improves mechanics, thermomechanics, electronics or other physical and chemical properties, especially for catalyst polymer matrix composites. Factors such as carbonaceous matrix preparation temperature, origin of this matrix or biomass, pH and synthesis conditions can positively or negatively affect the electron transfer process in the composite, making the composite efficient or not in the degradation of organic pollutants in aqueous media. The application of a carbonaceous matrix in the formation of photocatalytic composites has numerous advantages, as will be seen throughout the chapter. The presence of a carbonaceous matrix facilitates the process of removing the photocatalyst from the medium, facilitates the electron transfer process, requiring less energy to activate the photocatalyst. It is also possible to use carbon from organic waste, such as biomass, reducing the cost of producing composites. These and other advantages will be discussed throughout the chapter, as well as the influence of the synthesis process to obtain a composite with very high photocatalytic efficiency to be applied in the degradation of emerging pollutants.

Electrocatalysis can be defined as the heterogeneous catalysis of electrochemical reactions, occuring at the electrode–electrolyte interface and where the electrode plays both the role of electron donor/acceptor and of catalyst. Fuel cells, batteries and capacitors, hydrogen peroxide sensors, glucose sensors, and heavy metal sensors are the electrochemical sensors catalyzed via electrocatalysts such as Pt, Pd, and other metallic catalysts. These noble materials are expensive and thus should be replaced non noble and unexpensive ones. In this context, carbon composite catalysts are promising candidates. In this chapter, carbon composite catalysts and their applications as fuel cell anode and cathode catalysts, sensor materials for hydrogen peroxide sensors, glucose sensors, and heavy metal sensors, and materials for batteries and capacitor are investigated.

The Industrial wastewater particularly from Textile industry has caused effect of pollution on the environment. This study contain an overview of the production of activated carbon (AC) from bio-waste material. The methods for treatment of Industrial wastewater focussed on textile industry dye removal are discussed in this paper. This review presents a detailed explanation of the development, preparation, characterization and properties of activated carbon derived from agricultural waste. The application of the derived activated carbon in textile industry in general and dye removal (Methylene blue and Methyl orange) in textile industry specifically is discussed. The currently available Dye removal technique is summarized and their benefits and drawback are compared. Therefore, it is proven that we can use relatively inexpensive and renewable sources of the bio-waste to be very effective in terms of cost and adsorbent capacity and it can fruitfully replace the available but expensive material.