Direct Anchoring of Molybdenum Sulfide Molecular Catalysts on Antimony Selenide Photocathodes for Solar Hydrogen Production

Molybdenum sulfide serves as an effective nonprecious metal catalyst for hydrogen evolution, primarily active at edge sites with unsaturated molybdenum sites or terminal disulfides. To improve the activity at a low loading density, two molybdenum sulfide clusters, [Mo₃S₄]⁴⁺ and [Mo₃S₁₃]^2-, were investigated. The Mo₃S _x molecular catalysts were heterogenized on Sb₂Se₃ with a simple soaking treatment, resulting in a thin catalyst layer of only a few nanometers that gave up to 20 mA cm^-2 under one sun illumination. Both [Mo₃S₄]⁴⁺ and [Mo₃S₁₃]^2- exhibit catalytic activities on Sb₂Se₃, with [Mo₃S₁₃]^2- emerging as the superior catalyst, demonstrating enhanced photovoltage and an average faradaic efficiency of 100% for hydrogen evolution. This superiority is attributed to the effective loading and higher catalytic activity of [Mo₃S₁₃]^2- on the Sb₂Se₃ surface, validated by X-ray photoelectron and Raman spectroscopy.