Silver Nanowires Cascaded Layered Double Hydroxides Nanocages with Enhanced Directional Electron Transport for Efficient Electrocatalytic Oxygen Evolution.

Abstract

Designing and fabricating highly efficient oxygen evolution reaction (OER) electrocatalytic materials for water splitting is a promising and practical approach to green and sustainable low-carbon energy systems. Herein, a facile in situ growth self-template strategy by using ZIF-67 as a consumable layered double hydroxides (LDHs) template and silver nanowires (AgNWs) as 1D conductive cascaded substrate to controllably synthesize the target AgNWs@CoFe-LDH composites with unique hollow shell sugar gourd-like structure and enhanced directional electron transport effect is reported. The AgNWs exhibit the key functions of the close connection of CoFe-LDH nanocages and the support of the directional electron transport effect in the composite catalyst inducing electrons directionally moving from CoFe-LDH to AgNWs. Meanwhile, the CoFe-LDH nanocages with ultrathin nanosheets and hollow structural properties show abundant active sites for electrocatalytic oxygen generation. The versatile AgNWs@CoFe-LDH catalyst with optimized components, enhanced directional electron transport, and synergistic effect achieves high OER performance with the overpotential of 207 mV and long-term 50 h stability at 10 mA cm-2 in an alkaline medium. Moreover, in-depth insights into the microstructure, structure-activity relationships, identification of key intermediate species, and a proton-coupled four-electron OER mechanism based on experimental discovery and theoretical calculation are also demonstrated.