In situ synthesis of morphology-controlled MoOx/Fe1−xS bifunctional catalysts for high-efficiency and stable alkaline water splitting

Abstract

The advancement of a bifunctional electrocatalyst consisting of Earth's rich elements and exhibiting high efficiency is the key to obtain hydrogen fuel by overall water splitting (OWS). Here, a facile and extensible hydrothermal synthesis of an electrocatalyst on iron foam (MoO_x/Fe_1−xS/IF) as a robust bifunctional catalyst with excellent catalytic activity is designed for the hydrogen evolution reaction (HER) with an overpotential of 142 mV at 100 mA cm⁻², and for the OER with lower overpotentials of 300 and 500 mV at 100 and 1000 mA cm⁻². The good activity is ascribed to the controllable morphology, stronger bonding of the catalyst to a substrate and optimized electronic configuration. When used as bifunctional electrocatalysts toward alkaline overall water splitting, MoO_x/Fe_1−xS/IF delivers a current density of 10 mA cm⁻² at a low cell voltage of 1.56 V for 110 h. Such high performance coupled with low-cost iron-based materials suggests that the present strategy may open new avenues for the rational design of electrocatalysts and for use in practical water splitting.