Simultaneously Optimizing the Number and Efficiency of Active Se Sites in Se-Rich a-MoSex Nanodot Cocatalysts for Efficient Photocatalytic H-2 Evolution

MoSe2 as a cost-effective cocatalyst is of huge interest for photocatalytic water splitting. However, the H-2-production activity of the bulk MoSe2 is still unsatisfactory because its interfacial H-2-generation rate is dominantly hindered by its insufficient and low-efficiency Se sites. Herein, Se-rich amorphous MoSex nanodots (a-MoSex) as a novel H-2-evolution cocatalyst are fabricated onto TiO2 via a lactic acid-induced hydrolysis pathway. The as-synthesized a-MoSex cocatalyst displays an ultrasmall and amorphous structure, especially Se-rich property, which distinctly maximizes the number of active Se sites and optimizes H-2-production efficiency of Se atoms. Ultimately, the optimized a-MoSex/TiO2(1 mL) photocatalyst delivers a superior H-2-evolution rate of 86.28 mu mol h(-1), which is about 76.4- and 2.5-fold of the pure TiO2 and the crystalline MoSe2 modified-TiO2 samples, respectively. Combined with the experimental investigations and density functional theory (DFT) calculations, the Se-rich amorphous MoSex nanodots can not only effectively promote the photoexcited charge separation, but also achieve the simultaneous optimization of the number and H-2-evolution efficiency of active Se sites, thus actually improving photocatalytic H-2-production activity of TiO2. This work offers a new paradigm to simultaneously optimizing the number and efficiency of active Se sites for interfacial H-2 evolution, which delivers an inspiration on constructing highly efficient cocatalysts for solar-energy conversion.