Facile synthesis of CeO2-decorated W@Co-MOF heterostructures as a highly active and durable electrocatalyst for overall water splitting

Abstract

Rational coupling of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalysts is extremely important for practical overall water splitting; however, it is still challenging to construct such bifunctional heterostructures. Herein, a CeO₂/W@Co-MOF/NF bifunctional electrocatalyst was prepared via a two-step in situ growth method involving an electrodeposition process. The incorporation of the W element enhanced the electronic interaction and enlarged the electrochemical surface area. After the electrodeposition of CeO₂, the obtained CeO₂/W@Co-MOF/NF possessed abundant heterointerfaces with a modulated local distribution, which promoted water dissociation and rapid electrocatalytic kinetics. In particular, it required very low overpotentials of 239 mV and 87 mV to reach a current density of 10 mA cm⁻² in OER and HER, respectively. A corresponding alkaline electrolysis cell afforded a cell voltage of 1.54 V at 10 mA cm⁻² to boost overall water splitting. This work provides a feasible strategy to fabricate MOF-based complexes and explores their possible use as bifunctional catalysts toward overall water splitting.