Copper-driven catalyst design for improved oxygen reduction reactions in carbon-based materials

<p indent="0mm">Electro-Fenton process is one of the simple and effective methods for the treatment of organic pollutants in water. Carbon-based material serves as a robust cathode for <italic>in-situ</italic> formation of H₂O₂<italic> via </italic>the two-electron O₂ reduction reaction. With the help of electro-Fenton catalysts, the generated H₂O₂ decomposed into strong oxidizing hydroxyl radicals for efficient mineralization of organic pollutants. Based on the analysis of the main electro-Fenton processes on carbon-based materials, this review systematically summarizes the modification of various carbon-based electrode in an attempt to enhance O₂ mass transfer and Fenton reaction. Moreover, the practical application and economic cost of carbon-based electrode in electro-Fenton degradation of organic pollutants are described. Finally, the current development trend of carbon-based electrode materials and foreseeable future research direction in the field of electro-Fenton pollution control are pointed out.

Fuel cells are a promising alternative to non-renewable energy production industries such as petroleum and natural gas. The cathodic oxygen reduction reaction (ORR), which makes fuel cell technology possible, is sluggish under normal conditions. Thus, catalysts must be used to allow fuel cells to operate efficiently. Traditionally, platinum (Pt) catalysts are often utilized as they exhibit a highly efficient ORR with low overpotential values. However, Pt is an expensive and precious metal, posing economic problems for commercialization. Herein, advances in carbon-based catalysts are reviewed for their application in ORRs due to their abundance and low-cost syntheses. Various synthetic methods from different renewable sources are presented, and their catalytic properties are compared. Likewise, the effects of heteroatom and non-precious metal doping, surface area, and porosity on their performance are investigated. Carbon-based support materials are discussed in relation to their physical properties and the subsequent effect on Pt ORR performance. Lastly, advances in fuel cell electrolytes for various fuel cell types are presented. This review aims to provide valuable insight into current challenges in fuel cell performance and how they can be overcome using carbon-based materials and next generation electrolytes.

3D carbon nanotubes-graphene hybrids for energy conversion and storage applications

Nanocarbons and their hybrids as catalysts for non-aqueous lithium–oxygen batteries

At present, the energy shortage and environmental pollution are the burning global issues. For centuries, fossil fuels have been used to meet worldwide energy demand. However, thousands of tons of greenhouse gases are released into the atmosphere when fossil fuels are burned, contributing to global warming. Therefore, green energy must replace fossil fuels, and hydrogen is a prime choice. Photocatalytic water splitting (PWS) under solar irradiation could address energy and environmental problems. In the past decade, solar photocatalysts have been used to manufacture sustainable fuels. Scientists are working to synthesize a reliable, affordable, and light-efficient photocatalyst. Developing efficient photocatalysts for water redox reactions in suspension is a key to solar energy conversion. Semiconductor nanoparticles can be used as photocatalysts to accelerate redox reactions to generate chemical fuel or electricity. Carbon materials are substantial photocatalysts for total WS under solar irradiation due to their high activity, high stability, low cost, easy production, and structural diversity. Carbon-based materials such as graphene, graphene oxide, graphitic carbon nitride, fullerenes, carbon nanotubes, and carbon quantum dots can be used as semiconductors, photosensitizers, cocatalysts, and support materials. This review comprehensively explains how carbon-based composite materials function as photocatalytic semiconductors for hydrogen production, the water-splitting mechanism, and the chemistry of redox reactions. Also, how heteroatom doping, defects and surface functionalities, etc., can influence the efficiency of carbon photocatalysts in H2 production. The challenges faced in the PWS process and future prospects are briefly discussed.

Research advances in biomass-derived nanostructured carbons and their composite materials for electrochemical energy technologies

Chapter 8 - Advanced carbon-based nanostructured materials for fuel cells

Carbon-based materials have enabled the fabrication of various energy conversion and storage devices with enhanced performances. In this paper, we review in detail different nanostructured carbon-based materials (such as commercial carbon, carbon nanotube/nanofibre, graphene, porous carbon, functionalised carbon, and composite carbon materials with noble metals and metal oxides) as cathodes for non-aqueous Li-O2 batteries. From a materials point of view, the latest trends (mostly since 2012) in the design of catalysts for non-aqueous Li-O2 batteries are discussed. Finally, a summary and outlook for nanostructured carbon-based materials for non-aqueous Li-O2 batteries are presented, including the challenges that lie ahead.

Proton exchange membrane fuel cell (PEMFC) has important implications for the success of clean transportation in the future. One of the key factors affecting the cost and performance of PEMFC is the cathode electrocatalyst for the oxygen reduction reaction (ORR) to overcome sluggish kinetics and instability in an acidic environment. As an essential component of the electrocatalyst, the support material largely determines the activity, mass transfer, charge transfer, and durability of the electrocatalyst. Thereby, the support material plays a critical role in the overall performance of the electrocatalyst. Carbon-based materials are widely used as electrocatalyst supports because of their high porosity, conductivity, chemical stability, and tunable morphology. Recently, some new carbon-based materials with excellent structure have been introduced, such as carbon nanotubes, carbon nanowires, graphene, metal–organic framework (MOF)-derived carbon, and biomass-derived carbon materials. Combined with a variety of strategies, such as controllable construction of porous structures and surface defects, proper doping heteroatoms, the ingenious design of model electrocatalysts, and predictive theoretical calculation, a new reliable path was provided for further improving the performance of electrocatalysts and exploring the catalytic mechanism. Based on the topic of carbon-based materials for ORR in acidic medium, this review summarizes the up-to-date progress and breakthroughs, highlights the factors affecting the catalytic activity and stability of ORR electrocatalysts in acids, and discusses their future application and development.

Performance of ion intercalation materials in capacitive deionization/electrochemical deionization: A review

Electrochemical synthesis of hydrogen peroxide (H2 O2 ) through the selective oxygen reduction reaction (ORR) offers a promising alternative to the energy-intensive anthraquinone method, while its success relies largely on the development of efficient electrocatalyst. Currently, carbon-based materials (CMs) are the most widely studied electrocatalysts for electrosynthesis of H2 O2 via ORR due to their low cost, earth abundance, and tunable catalytic properties. To achieve a high 2e- ORR selectivity, great progress is made in promoting the performance of carbon-based electrocatalysts and unveiling their underlying catalytic mechanisms. Here, a comprehensive review in the field is presented by summarizing the recent advances in CMs for H2 O2 production, focusing on the design, fabrication, and mechanism investigations over the catalytic active moieties, where an enhancement effect of defect engineering or heteroatom doping on H2 O2 selectivity is discussed thoroughly. Particularly, the influence of functional groups on CMs for a 2e- -pathway is highlighted. Further, for commercial perspectives, the significance of reactor design for decentralized H2 O2 production is emphasized, bridging the gap between intrinsic catalytic properties and apparent productivity in electrochemical devices. Finally, major challenges and opportunities for the practical electrosynthesis of H2 O2 and future research directions are proposed.

Wood based quasi-solid-state Zn-air battery with dual honeycomb-like porous carbon and cationic nanocellulose film

The development of highly efficient and sustainable electrocatalytic technologies offers a significant solution to the growing global demand for energy, as well as to the achievement of carbon neutrality goals, where its success relies on the design and fabrication of electrocatalysts. Currently, carbon-based materials are promising alternative materials due to the tunable electronic structure, high conductivity, excellent stability, and abundant reserves; however, inherent inert structure significantly limits its catalytic activity. Herein, incorporating oxygen functional groups (OFGs) into carbon-based materials has been reviewed as a pivotal strategy to regulate electronic structure, charge transfer processes, and adsorption energy toward reaction intermediates, thereby enhancing electrocatalytic performance. The latest research progress of OFGs in crucial electrocatalytic reaction such as oxygen reduction reaction, CO2 reduction reaction, and oxygen evolution reaction is systematically reviewed, deeply exploring core mechanisms of reaction kinetics regulation, while summarizing the precise structure-function relationships of different OFGs types in multireaction systems. Further, technical challenges and prospective opportunities in precise design and modulation of OFGs are discussed, offering a basis for research focusing on dynamic controllable strategies and optimal design of interfacial microenvironments. Finally, research insights and technical pathways of developing low-cost and high-performance oxygen-functionalized carbon-based materials for electrocatalytic applications are provided.

Rational design of highly efficient carbon-based materials for electrochemical CO2 reduction reaction

Recent advances in multilevel nickel-nitrogen-carbon catalysts for CO2electroreduction to CO