Multifunctional catalytic sites regulation of atomic-scale iridium on orthorhombic-CoSe2 for high efficiency dual-functional alkaline hydrogen evolution and organic degradation

The earth-abundant and high-performance catalysts are crucial for commercial implementation of hydrogen evolution reaction (HER). Herein, a multifunctional site strategy to construct excellent HER catalysts by incorporating iridium (Ir) ions on the atomic scale into orthorhombic-CoSe2 (Ir-CoSe2) was reported. Outstanding hydrogen evolution activity in alkaline media such as a low overpotential of 48.7 mV at a current density of 10 mA cm−2 and better performance than commercial Pt/C catalysts at high current densities were found in the Ir-CoSe2 samples. In the experiments and theoretical calculations, it was revealed that Ir enabled CoSe2 to form multifunctional sites to synergistically catalyze alkaline HER by promoting the adsorption and dissociation of H2O (Ir sites) and optimizing the binding energy for H* on Co sites. It was noticeable that the electrolytic system comprising the Ir-CoSe2 electrode not only produced hydrogen efficiently via HER, but also degraded organic pollutants (Methylene blue). The cell voltage of the dual-function electrolytic system was 1.58 V at the benchmark current density of 50 mA cm−2, which was significantly lower than the conventional water splitting voltage. It was indicated that this method was a novel strategy for designing advanced HER electrocatalysts by constructing multifunctional catalytic sites for hydrogen production and organic degradation.