A Review of Carbon‐Supported Nonprecious Metals as Energy‐Related Electrocatalysts

Abstract

development of sustainable energy conversion and storage technologies. [1] Nowadays, the electrolysis of oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and carbon dioxide reduction reaction (CO 2 RR) is being extensively researched. [2] The conversion efficiencies of these electrochemical reactions are critical to the performance of sustainable energy devices, including fuel cells, metal-air batteries, and electrolyzers. [3] Particularly, ORR is the cathode reaction of fuel cells which are characterized by a higher energy efficiency than that of conventional combustion engines. [4] ORR and OER occur at the gas electrode of a rechargeable metal-air battery. [5] In the production of electro-fuels (e.g., H 2 or CO), HER and CO 2 RR serve as the cathode reactions in electrolyzers with H 2 O and CO 2 as the reactants, respectively. [6] The development of high-performance electrocatalysts is critical for the mass adoption of those sustainable energy applications. [7] Carbon-supported nonprecious metals (C@NPMs) have recently attracted significant attention for the promotion of the above-mentioned reactions during electrolysis owing to their low cost and potentially high activity. [8] Carbon frameworks can be easily modified and can take the form of various nanostructures, such as 1D carbon nanotubes (CNTs), [9] 2D graphene, [10] and 3D porous carbons. [11] The coupling of nonprecious metals with carbons can mitigate the corrosion issues of these metals under harsh electrolysis conditions (e.g., strong alkaline/acidic electrolytes and oxidative potentials), and reduce agglomeration by enhancing the dispersion of the metal moieties. [12] In addition, the coupling can promote charge transfer between the carbon and the metal components, thereby tuning the electronic structure for catalysis. [13] Thus, the carbon support not only works as a conductive substrate but also interacts electronically with the metal species, modifying the electronic/ electrochemical properties of the composite. [14] The catalytic properties of C@NPMs can be further optimized by introducing heteroatom dopants, engineering topological defects, modulating metal size, tuning the carbon shell, and coupling multimetals. [15] Owing to the tremendous efforts of the research community in this field, C@NPMs have seen significant advancements. For instance, Fe or Co coupled with N-doped carbon, i.e., FeNC and CoNC are one of the most promising ORR electrocatalysts to replace precious Pt in both acidic and alkaline electrolytes. [16] The development of sustainable energy conversion and storage devices, such as fuel cells, metal-air batteries, and electrolyzers is highly dependent on the catalytic oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and carbon dioxide reduction reaction (CO 2 RR). Carbon-supported nonprecious metals (C@NPMs) with variable metal sizes (single atom, cluster, and nanoparticle) are attracting significant interest for catalyzin...

Deep Eutectic Solvents for Boosting Electrochemical Energy Storage and Conversion: A Review and Perspective

“…Among various alternatives, pyridinic nitrogen (N) doped carbons attract significant attention due to their high stability and excellent activity. [139,166] As mentioned in Section 3.2, plenty of N-doped carbon materials can be prepared by using DESs as precursors. Therefore, it is practicable to prepare ORR catalysts based on DESs because the dopant and graphitization of carbon can be integrated tactfully.…”

Simultaneously Crafting Single‐Atomic Fe Sites and Graphitic Layer‐Wrapped Fe3C Nanoparticles Encapsulated within Mesoporous Carbon Tubes for Oxygen Reduction

“…More importantly, the size effect of Fe metal remains complicated, and smaller metal species (atomically dispersed Fe-N x sites) do not necessarily improve the electrolysis significantly. [12,13] In this context, metallic iron nanoparticles (NPs) have been suggested as either active sites or synergistic sites in conjunction with Fe-N x configurations to accelerate the ORR. [8,14] Therefore, the implementation of metallic iron NPs in a Fe-N-C catalyst represents a promising route to improve the ORR kinetics.…”

Tuning Reconstruction Level of Precatalysts to Design Advanced Oxygen Evolution Electrocatalysts

“…Meanwhile, noble-metal-based electrocatalysts are greatly limited when used in commercial applications due to their scarcity and high cost. Therefore, tremendous efforts have been devoted to the development of efficient OER catalysts that cost less [ 17 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ].…”