Progress on Bifunctional Carbon‐Based Electrocatalysts for Rechargeable Zinc–Air Batteries Based on Voltage Difference Performance.

Zinc–air batteries (ZABs) hold potential as clean, cost‐effective, and sustainable energy storage system for the next generation. However, the application of ZABs remains challenging because of their poor rechargeability and low efficiency. The design of efficient bifunctional catalysts toward oxygen reduction reaction (ORR) during discharging and the oxygen evolution reaction (OER) during charging is essential to developing rechargeable ZABs. Transition metal (TM)‐doped carbon (TM‐C) materials stand out from all the available bifunctional catalysts due to the excellent specific surface area, diverse morphological structures , and the multiple metal active sites formed after TM doping. This paper, therefore, focuses on the synthesis, electrochemical properties, and potential mechanism of TM‐C catalysts. To make a novelty and logical statement, the voltage difference (ΔE = Ei = 10 − E1/2) between the ORR/OER catalytic process is employed to categorize different TM‐C catalysts reported in recent years, which are divided into two groups: I (ΔE = 0.7 − 0.9 V) and II (ΔE = 0.5 − 0.7 V). The catalytic mechanisms of bifunctional catalysts are clarified. More ways and ideas for synthesizing high‐performance bifunctional TM‐C catalysts are also provided. Finally, the current problem and prospects of this group materials are presented. [ABSTRACT FROM AUTHOR]