Tunning the electrochemical performance of rhenium disulfide (ReS2) nanoparticles by heat treatment

The effect of annealing temperature on the structural, chemical, and electrochemical properties of rhenium disulfide (ReS 2 ) catalysts is systematically investigated. ReS 2 materials were synthesized from ammonium perrhenate (NH 4 ReO 4 ) using an impinging jet reactor. The materials were annealed at 350, 550, and 850 °C. X-ray photoelectron spectroscopy (XPS) highlights significant changes in the oxidation state of rhenium, with the formation of rhenium oxysulfide (ReO x S y ) phases at 550 °C. These phases, along with the partial amorphous nature of the material, are found to enhance electrical conductivity and catalytic activity, as indicated by electrochemical investigations. Electrochemical measurements demonstrate that the sample annealed at 550 °C exhibits the best hydrogen evolution reaction (HER) performance, achieving the lowest overpotential of −0.2 V at −2 mA/cm 2 , due to the optimal balance of defect sites, specific surface area, and electrical conductivity. These results underscore the critical role of annealing temperature in tuning the physical and electrochemical characteristics of ReS 2 , offering insights into the design of high-performance catalysts for energy conversion applications. • An impinging jet reactor enables efficient synthesis of ReS 2 nanoparticles. • Heat treatment alters chemical state and electrochemical performance of ReS 2 . • Formation of ReO x S y and lattice defects boost electrochemical response of ReS 2 . • ReS 2 annealed at 550 °C exhibits overpotential of −0.2 V at −2 mA/cm 2 . • Study offers guidance for designing efficient energy conversion catalysts.