Surface defect engineering in Mo-doped ReS2/CoS2 heterostructure catalysts for enhanced electrocatalytic water splitting

Abstract

Designing efficient electrocatalysts with heterostructure is crucial for enhancing electrocatalytic performance due to their strong interaction at the interface. Herein, the vertical growth of Mo-doped ReS₂ on MOF-derived cobalt disulfides is constructed on the surface of carbon fiber paper (Mo-ReS₂/CoS₂/CFP) via the sulfidation and hydrothermal treatments. Elemental Mo doping in ReS₂ not only modifies the electronic structure of ReS₂, but also facilitates charge redistribution to improve the electrical conductivity and boost the catalytic active sites during the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) process. The presence of Mo doping increases the number of active sites, resulting in the improved overall catalytic efficiency. Meanwhile, the formation of heterostructure can strengthen the bond interaction at the interface to improve the catalytic durability of the catalyst. The overall mechanism of enhanced performance is attributed to the optimized electronic properties and enhanced charge transfer, which is crucial for high-efficiency electrochemical reactions. Mo-ReS₂/CoS₂/CFP exhibits the lowest overpotential of 78 and 249 mV at 10 mA cm⁻² for the HER and OER process in alkaline electrolyte. The exceptional catalytic activities have been further confirmed by the low Tafel slope with the Volmer-Heyrovsky mechanism, small charge transfer resistance, and good catalytic durability. This work provides a promising concept for constructing the ReS₂-based heterostructure as an advanced electrocatalyst for hydrogen production.