Defect engineering induces Mo-regulated Co9Se8/FeNiSe heterostructures with selenium vacancy for enhanced electrocatalytic overall water splitting in alkaline

The Mo-Co9Se8/FeNiSe interface catalyst with rich selenium vacancy defects shows excellent performance in electrocatalytic overall water splitting, which provides a reasonable design scheme for improving the water splitting performance of transition metal selenides heterostructures. [Display omitted] •Mo-Co9Se8/FeNiSe interface catalyst was in-situ synthesized on the surface of nickel foam without binder.•The Mo-Co9Se8/FeNiSe/NF interface catalyst with selenium vacancy defects has excellent water splitting performance.•Mo-Co9Se8/FeNiSe still has outstanding stability at 100 mA/cm2 current density.•This work presents a new perspective to design and synthesis of non-precious metal selenide-based electrocatalysts. The pursuit of cost-effective catalysts for electrocatalytic overall water splitting continues to present a significant challenge in the field. A molybdenum (Mo)-regulated Co9Se8/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-Co9Se8/FeNiSe heterostructure. Additionally, the Faraday efficiency of hydrogen (H2) and oxygen (O2) production approaches 100 %. The voltage required for the water-splitting system is only 1.58 V (10 mA cm−2), and 100 h stability test at 100 mA cm−2 demonstrates no decay. This work presents a new perspective for the reasonable design and synthesis of non-precious metal selenide-based bifunctional electrocatalysts.