Interfacial Coupling Engineering Boosting Electrocatalytic Performance of CoFe Layered Double Hydroxide Assembled on N-Doped Porous Carbon Nanosheets for Water Splitting and Flexible Zinc-Air Batteries.

Abstract

The disadvantages of layered double hydroxides (LDHs) such as easy stacking, poor inherent conductivity, and limited versatility hinder their application in splitting water and zinc-air batteries (ZABs). Interface engineering to regulate the electron distribution of LDHs by introducing another component is a way to compensate for the poor electron transport capacity of LDHs during catalysis. Herein, a hierarchical structure is synthesized by assembling CoFe-LDH nanosheets onto the surface of layered N-doped porous carbon (NPC), CoFe-LDH@NPC, by using an interface engineering strategy. CoFe-LDH@NPC has high catalytic activity for the oxygen/hydrogen evolution reaction (OER/HER) with overpotentials of 280/100 mV, respectively. The two-electrode water splitting catalyzed by CoFe-LDH@NPC only needs 1.61 V to drive a current density of 10 mA cm-2 for 60 h. The theoretical results show that there is an electron-deficient/electron-rich interface between the NPC substrate and the CoFe-LDH in CoFe-LDH@NPC. The electrons on the coupling interface are easily transferred, which results in a change of the adsorption behavior of the reaction intermediates and improves the catalytic activity for the OER and HER. In addition, CoFe-LDH@NPC-catalyzed rechargeable flexible ZABs have excellent performance with low charge-discharge polarization (0.87 V) and a long-term stability of 65 h.