Fast Current‐Driven Synthesis of ZIF‐Derived Catalyst Layers for High‐Performance Zn‐Air Battery

Abstract

As a core component, the catalyst layer (CL) is widely used in fuel cell, metal‐air battery, and other energy conversion devices. Herein, a highly efficient method for CL preparation via fast current‐driven synthesis followed by pyrolysis is proposed. Compared with previously reported fabrication procedures of zeolite imidazolate frameworks (ZIF)‐based CLs, this method directly deposits the ZIF precursor onto the conductive substrate in a very short time (≤15 min). The self‐supporting CL, converted from ZIF membrane by simple single‐step pyrolysis, is assembled with the gas diffusion layer to obtain cathode. Electrochemical tests exhibit a small potential gap (0.83 V) between the oxygen reduction and evolution reactions, as well as high performance and excellent stability for Zn‐air battery (241 mW cm–2 at 390 mA cm–2), due to the unique design of a bi‐continuous framework (interconnected pores and long carbon nanotubes) and Co‐based active sites. This work may provide new directions for the fast fabrication of non‐platinum group metal CLs for metal‐air batteries or fuel cell applications.

Fe, N-Doped Hollow Porous Carbon Spheres Decorated with Ultrasmall Co NPs as Efficient Bifunctional Electrocatalysts for Rechargeable Zinc–Air Batteries

“…To meet the above demands, zeolitic imidazolate frameworks (ZIFs) materials are especially ideal candidates because they have regulated heteroatom components, i.e., nitrogen, oxygen, 12 transition metals, 13 and carbon. 14 electrocatalysts usually demonstrate metal NPs agglomeration, monomicroporous channels, and morphologic/structural destruction, resulting in an inferior performance, i.e., poor cyclic durability and catalytic activity loss for the rechargeable ZABs. 15,16 Thus, introduction of ZIFs nanomaterials into the hierarchically porous carbon will be a promising strategy to synthesize excellent bifunctional electrocatalysts, which expose more active sites, facilitate mass transport, and shorten transmission pathways of the O 2 /electrolyte during the charge−discharge process.…”

“…Generally, a high-performance bifunctional catalyst for ORR/OER should possess several superiorities, i.e., (i) high specific surface area and hierarchical porous structure ensure the short diffusion distances of electrolyte and reactant to the catalytic active sites; (ii) uniform distribution of multicomponent active dopants, i.e., Fe, Co, N, etc., affords highly exposed active sites; (iii) the generation of numerous defects can contribute new catalytic active sites. To meet the above demands, zeolitic imidazolate frameworks (ZIFs) materials are especially ideal candidates because they have regulated heteroatom components, i.e., nitrogen, oxygen, transition metals, and carbon . Nevertheless, ZIFs-derived electrocatalysts usually demonstrate metal NPs agglomeration, monomicroporous channels, and morphologic/structural destruction, resulting in an inferior performance, i.e., poor cyclic durability and catalytic activity loss for the rechargeable ZABs. , Thus, introduction of ZIFs nanomaterials into the hierarchically porous carbon will be a promising strategy to synthesize excellent bifunctional electrocatalysts, which expose more active sites, facilitate mass transport, and shorten transmission pathways of the O 2 /electrolyte during the charge–discharge process.…”