Trimetallic CoNiFe-layered double hydroxides: Electronic coupling effect and oxygen vacancy for boosting water splitting

Developing cost-effectively bifunctional electrocatalysts with high activity sites and optimized intrinsic activity is still an enormous challenge. Here, a trimetallic CoNiFe-layered double hydroxide (LDH) hollow superstructure grown on carbon cloth is ingeniously fabricated through an aging and etching-coprecipitating method. Remarkably, electron cloud density of active sites and adsorption for reaction intermediate are optimized by the strong electronic coupling effect and the abundant oxygen vacancies, which can endow catalysts with marvelous intrinsic activity for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). As a consequence, the trimetallic CoNiFe-LDH catalyst requires low overpotentials toward HER (143 mV at 10 mA cm−2) and OER (219 mV at 20 mA cm−2) in 1.0 M KOH, enabling an alkaline electrolyzer to deliver a low cell voltage of 1.56 V at 10 mA cm−2 that are superior to most reported LDH catalysts. This work reports a high activity bifunctional OER/HER electrocatalysts, which may open numerous opportunities to the development of trimetallic LDH catalysts in hydrogen production.