Carbon‐Based Electrocatalysts for Acidic Oxygen Reduction Reaction

Abstract

Oxygen reduction reaction (ORR) is vital for clean and renewable energy technologies, which require no fossil fuel but catalysts. Platinum (Pt) is the best-known catalyst for ORR. However, its high cost and scarcity have severely hindered renewable energy devices (e.g., fuel cells) for large-scale applications. Recent breakthroughs in carbon-based metal-free electrochemical catalysts (C-MFECs) show great potential for earth-abundant carbon materials as low-cost metal-free electrocatalysts towards ORR in acidic media. This article provides a focused, but critical review on C-MFECs for ORR in acidic media with an emphasis on advances in the structure design and synthesis, fundamental understanding of the structure-property relationship and electrocatalytic mechanisms, and their applications in proton exchange membrane fuel cells. Current challenges and future perspectives in this emerging field are also discussed.

Recent Progress on Carbon‐Based Electrocatalysts for Oxygen Reduction Reaction: Insights on the Type of Synthesis Protocols, Performances and Outlook Mechanisms

“…It is important to note that the amount of heteroatom doping on carbonaceous materials, which changes the charge and spin distribution as well as the bandgap, is crucial in improving the ORR electrocatalytic activity of such materials. The most significant difference and highlight between [154][155][156][157][158] and this review is the differentiation made between heteroatom doped carbon nanomaterials and those functionalized with various functional groups in terms of ORR performance, fuel cell application, and ORR mechanism in acidic and alkaline mediums.…”

Recent advances in atomically precise metal nanoclusters for electrocatalytic applications

“…The fuel cell reaction (FCR) is a vital step in converting the chemical energy of fuels into clean and stable electricity and has extensive applications in transportation and energy storage. 54–56 NCs have been employed as efficient catalysts in the FCR in recent years, benefiting from their high specific surface area, uniform size and well-defined structure. In 2018, Lu et al investigated the catalytic activity difference between Au 25 and Pt 1 Au 24 NCs for formic acid oxidation (FAO).…”

Component-controlled synthesis of PdxSny nanocrystals on carbon nanotubes as advanced electrocatalysts for oxygen reduction reaction

“…6–10 Pt-based catalysts are currently the dominant type of catalysts for oxygen reduction, but they suffer from low abundance, high cost, and poor resistance to CO molecules, which limit their commercial applications. 11–15 Consequently, exploring alternative non-Pt-based catalysts with enhanced ORR activity and stability has attracted extensive attention in recent years.…”

“…To date, many low-cost non-Pt-based catalysts have been explored, such as metal oxides, 16,17 heteroatom-doped carbon materials, 18–20 and metal–organic skeleton materials, 21–23 but these catalysts are far from meeting the requirements of high activity and stability of ORR. 4,13 Several approaches have been proposed to improve the ORR activity and stability of non-Pt-based catalysts, including regulating the electronic configuration, oxygen adsorption strength, and stability through compositional control and selecting appropriate catalyst supports. 24–28 As for the composition regulation, Pd-based catalysts, particularly Pd-based bimetallic catalysts, have been intensively investigated due to Pd's similar electronic configuration to Pt, higher abundance, and lower cost compared with Pt.…”