Electrocatalytic overall water splitting based on (ZnNiCoFeY)xOy high-entropy oxide supported on MoS2

Abstract

Hydrogen energy is a sustainable and clean source that can meet global energy demands without adverse environmental impacts. High-entropy oxides (HEOs), multielement (5 or more) oxides with an equiatomic or near-equatomic elemental composition, offer a novel approach to designing bifunctional electrocatalysts. This work explores (ZnNiCoFeY)_xO_y over MoS₂ as a bifunctional electrocatalyst (HEO–MoS₂) in an alkaline medium. The HEO was synthesized using a combustion process and loaded over MoS₂ using an ultrasonic method. The synthesized HEO over MoS2 exhibits excellent performance, including long-term stability for over 24 h, an overpotential of 214 mV vs the reversible hydrogen electrode (RHE) for the hydrogen evolution reaction (HER), and 308 mV for the oxygen evolution reaction (OER) at 10 mA cm⁻². This bifunctional electrocatalyst exhibits low overpotential for both the HER and the OER at high current densities. Additionally, HEO–MoS₂ demonstrates smaller solution and charge transfer resistance values. The electrolyzer was assembled using bifunctional HEO–MoS₂ electrodes for overall water splitting. These electrodes exhibited a low cell voltage of 1.65 V at 10 mA cm⁻². The novel electrocatalyst was fabricated using a facile and scalable method that appeals to industrial applications.