Recent Advances and Prospects of Metal‐Based Catalysts for Oxygen Reduction Reaction

Abstract

Fuel cells, as one of the most promising technologies in sustainable energy conversion systems, hold great expectations for commercial applications. Cathode oxygen reduction reaction (ORR) kinetics of fuel cells are very slow and require a large overpotential to make the reaction occur, which greatly limits the energy output of fuel cells. Therefore, designing and preparing a highly active and stable ORR catalyst has become a great challenge. Herein, recent advances in platinum‐based and platinum‐free materials in metal‐based catalysts are focused on, including structural properties, synthesis methods, performance characterization, and catalytic mechanisms. Although platinum‐based precious metal catalysts have excellent performance, high prices limit the scale of commercial fuel cells. Nonprecious metal catalysts (e.g., transition metal nitrogen‐doped carbon‐based catalysts (M‐N/C), transition metal compounds (transition metal oxides—TMOs, transition metal carbides—TMCs, transition metal nitrides/transition metal oxynitrides—TMNs/TMNOs), layered double hydroxides—LDHs) completely eliminate dependence on precious metals and exhibit excellent ORR catalytic activity and stability. Finally, the ideas for future design and preparation of new ORR catalysts and challenges in the future of research work are discussed.

Proton Exchange Membrane Fuel Cells (PEMFCs): Advances and Challenges

“…Single metal of platinum group metal (PGM), platinum group metal alloys, and single-atom-based metal oxides and metal nitrides are used like active catalysts for the oxygen reduction reaction (ORR) [222][223][224][225]. In literature, many reviews have recently reported [226][227][228] mentioning that some Pt-based alloy catalysts showed higher activity than Pt alone, and this has been attributed to changes in the Pt-Pt bond distance and Pt electronegativity [229], electron density in the 5d Pt band [230], and surface oxide layers [231].…”

A Review and Recent Developments in Full‐Spectrum Photocatalysis using ZnIn2S4‐Based Photocatalysts

“…In terms of the various technologies, semiconductor-based photocatalysis has emerged as a fascinating new technology because of its ability not only to directly use solar energy to produce valuable chemical fuels, but also to degrade harmful pollutants. [4][5][6] Since the discovery of photoelectrocatalytic splitting of water on TiO 2 electrodes by Fujishima and Honda in 1972, research on semiconductor materials has grown exponentially in the fields of photocatalysis. [7] TiO 2 , a typical semiconductor photocatalytic material, has gained particular interest in past decades owing to its superiority that it is low cost, nontoxic, and chemically stable.…”

The joint effect of electrical conductivity and surface oxygen functionalities of carbon supports on the oxygen reduction reaction studied over bare supports and Mn–Co spinel/carbon catalysts in alkaline media

“…silver, nickel), and nitrogen co-doped carbons have been investigated and used as the ORR catalysts. [16][17][18][19][20][21][22][23][24] Transition metal oxides (TMOs) of spinel structure are commonly applied as catalysts for the ORR in AEMFCs. Numerous TMOs exhibit satisfactory catalytic activity in the ORR and the oxygen evolution reaction (OER) with the advantages of being inexpensive, naturally abundant, and environmentally benign.…”