Defect engineering induces Mo-regulated CoSe/FeNiSe heterostructures with selenium vacancy for enhanced electrocatalytic overall water splitting in alkaline.

The pursuit of cost-effective catalysts for electrocatalytic overall water splitting continues to present a significant challenge in the field. A molybdenum (Mo)-regulated CoSe/FeNiSe self-supporting electrode material with rich vacancy defects has been prepared by hydrothermal reaction. Doping of Mo atoms not only can form rich selenium vacancy defects to enrich the inherent activity of the catalyst, but also expose more active sites. The intrinsic electronic architecture of the interface catalysis is regulated and optimized through the introduction of heteroatom Mo, resulting in the exceptional catalytic activities of the Mo-CoSe/FeNiSe heterostructure. Additionally, the Faraday efficiency of hydrogen (H) and oxygen (O) production approaches 100 %. The voltage required for the water-splitting system is only 1.58 V (10 mA cm), and 100 h stability test at 100 mA cm demonstrates no decay. This work presents a new perspective for the reasonable design and synthesis of non-precious metal selenide-based bifunctional electrocatalysts.