Elucidation of Active Sites on S, N Codoped Carbon Cubes Embedding Co–Fe Carbides toward Reversible Oxygen Conversion in High‐Performance Zinc–Air Batteries

Abstract

The development of high‐performance but low‐cost catalysts for the electrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of central importance for realizing the prevailing application of metal–air batteries. Herein a facile route is devised to synthesize S, N codoped carbon cubes embedding Co–Fe carbides by pyrolyzing the Co–Fe Prussian blue analogues (PBA) coated with methionine. Via the strong metal–sulfur interaction, the methionine coating provides a robust sheath to restrain the cubic morphology of PBA upon pyrolysis, which is proved highly beneficial for promoting the specific surface area and active sites exposure, leading to remarkable bifunctionality of ORR and OER comparable to the benchmarks of Pt/C and RuO2. Further elaborative investigations on the activity origin and postelectrolytic composition unravel that for ORR the high activity is mainly contributed by the S, N codoped carbon shell with the inactive carbide phase converting into carbonate hydroxides. For OER, the embedded Co–Fe carbides transform in situ into layered (hydr)oxides, serving as the actual active sites for promoting water oxidation. Zn–air batteries employing the developed hollow structure as the air cathode catalyst demonstrate superb rechargeability, energy efficiency, as well as portability.

Activity Promotion of Core and Shell in Multifunctional Core–Shell Co2P@NC Electrocatalyst by Secondary Metal Doping for Water Electrolysis and Zn‐Air Batteries

“…Ever-increasing concerns about dwindling fossil fuels and deteriorating environment have stimulated the rapid development of electrochemically renewable energy conversion and storage systems, such as water electrolysis, fuel cells, and metal-air HER/OER/ORR electrocatalysis. [20][21][22] As of now, there is still no report on the design of a well-defined TMPs@M-N-C system with excellent multifunctional HER/OER/ORR activities for efficient water electrolysis and Zn-air batteries.…”

Metal–organic framework based bifunctional oxygen electrocatalysts for rechargeable zinc–air batteries: current progress and prospects

“…12D). 135 The selection of methionine not only induced S doping, but also avoids the collapse of PBA, and the carbon shows a very high specic surface. XPS measurement indicated the presence of N and S species as well as metalnitrogen-carbon complexes, which is favourable for improved ORR activity.…”

Recent Advances in Enhancing Oxygen Reduction Reaction Performance for Non‐Noble‐Metal Electrocatalysts Derived from Electrospinning

“…The ORR electrocatalysts can be used not only in PEMFCs, but also in various energy‐supply devices involving ORR on cathode, such as metal (Li, [ 8–10 ] Al, [ 11–13 ] Zn, [ 14–16 ] etc.) air batteries.…”