Self-supported ZIF-coated Co2P/V3P bifunctional electrocatalyst for high-efficiency water splitting

Abstract

Exploring high-efficiency dual-functional electrocatalysts to drive electrochemical water splitting is of great importance for advancement of renewable hydrogen energy. Herein, a hierarchical core–shell structure electrocatalyst ZIF-Co2P/V3P is in situ grown on Ni foam (abbreviated as ZIF-Co2P/V3P@NF) by a stepwise method. Firstly, Co, V layered double hydroxides (CoV-LDHs) is grown directly on Ni foam (NF) substrate by solvothermal method. Secondly, CoV-LDHs@NF is transferred into 2-MeIm solution and its surface is coated with a layer of imidazolate zeolite skeleton (ZIF). Finally, ZIF-Co2P/V3P@NF catalyst is obtained by low-temperature phosphorization method. The performance of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) can be adjusted by tuning molar ratio of Co/V, and the optimized ZIF-Co2P/V3P@NF-2 manifests superior performance due to its core–shell structure covered by ZIF skeleton, rich heterogeneous interfaces, as well as the positive synergistic interaction between the Co2P and V3P. The overpotentials are only 57 mV@10 mA cm−2 for HER and 261 mV@10 mA cm−2 for OER. Remarkably, the alkaline electrolyzer assembled with ZIF-Co2P/V3P@NF-2 catalyst acquires a small operating voltage of 1.54 V to drive the current density of 10 mA cm−2 and displays excellent long-term durability. This work provides a novel opinion for design and preparation of non-noble metal electrocatalysts.