Fluorine-Expedited Sulfur Vacancy of Mn0.6Cd0.4S Photocatalyst Enables High-Efficiency Hydrogen Production

Developing efficient, stable, and low-cost photocatalysts is the key to achieving large-scale photocatalytic hydrogen production. Herein, a universal fluoride-induced sulfur vacancy engineering strategy is proposed for the full MnxCd1−xS solid solution series (x = 0.1–0.9), with Mn0.6Cd0.4S selected as the representative optimal sample. By introducing ammonium fluoride during the hydrothermal process, controllable sulfur vacancies are generated to enable efficient separation and transfer of photogenerated charge carriers for high-efficiency hydrogen production. Impressively, the optimal fluoride-modified Mn0.6Cd0.4S (F-MCS) photocatalyst shows the fastest hydrogen production rate up to 8.08 mmol·g−1·h−1, which is 1.5 times that of pure MCS nanoparticles, as well as enhanced photochemical stability. Quantitative EDS elemental analysis verifies that 1.2 at.% fluorine is incorporated into the lattice of F-MCS, rather than being physically adsorbed as residual ammonium fluoride precursors. Experimental results reveal that the introduction of NH4F can effectively facilitate the sulfur vacancy formation in MCS, which alters the band position of MCS nanoflakes for increased light harvesting, and serves carrier separation centers for promoting the efficient transfer of photogenerated charge carriers. This study provides valuable insights into the design of a solid solution-based photocatalyst for efficient solar-driven hydrogen production for sustainable energy applications.