Defect Engineering of MoS₂ and Its Impacts on Electrocatalytic and Photocatalytic Behavior in Hydrogen Evolution Reactions.

Molybdenum disulfide (MoS₂) has been regarded as a favorable photocatalytic co-catalyst and efficient hydrogen evolution reaction (HER) electrocatalyst alternative to expensive noble-metals catalysts, owing to earth-abundance, proper bandgap, high surface area, and fast electron transfer ability. In order to achieve a higher catalytic efficiency, defects strategies such as phase engineering and vacancy introduction are considered as promising methods for natural 2H-MoS₂ to increase its active sites and promote electron transfer rate. In this study, we report a new two-step defect engineering process to generate vacancies-rich hybrid-phase MoS₂ and to introduce Ru particles at the same time, which includes hydrothermal reaction and a subsequent hydrogen reduction. Compositional and structural properties of the synthesized defects-rich MoS₂ are investigated by XRD, XPS, XAFS and Raman measurements, and the electrochemical hydrogen evolution reaction performance, as well as photocatalytic hydrogen evolution performance in the ammonia borane dehydrogenation are evaluated. Both catalytic activities are boosted with the increase of defects concentrations in MoS₂, which ascertains that the defects engineering is a promising route to promote catalytic performance of MoS₂.