Tuning the sulfide interface of MnCo2O4-based nanostructures enables efficient water/seawater electrolysis

Abstract

Hydrogen generation through water electrolysis is greatly dependent on the development of energy and time-efficient techniques to construct stable and active electrocatalysts for oxygen evolution reaction (OER). Currently, major research focuses on producing hydrogen through direct seawater electrolysis instead of fresh water to build a sustainable society. However, competitive reactions such as chlorine evolution reaction (CIER) beyond OER and electrode erosion issues make seawater electrolysis more difficult. Here, we report an interfacial engineering strategy that constructs a MnCo₂O₄@CoS hybrid structure by sulfurization of the spinal MnCo₂O₄ nanowires. The hybrid structure demonstrates an excellent OER performance in electrolytes containing alkaline and saltwater. Specifically, the prepared catalyst needs overpotentials of 205 mV and 225 mV to deliver a current density of 10 mA cm⁻² in 1 M KOH and alkaline seawater when used as OER electrocatalysts. This should be noted that the CoS layer on the surface of MnCo₂O₄ nanowires not only acts as a Cl^‾ protective layer to impede electrode erosion and CIER but also provides metallic ions with a higher valence state to enhance the intrinsic catalytic activity of water oxidization. Thus, this type of electrocatalyst could represent a favorable choice, carrying substantial implications for hydrogen-based economies and environmental enhancement.