Tailoring the Porosity in Iron Phosphosulfide Nanosheets to Improve the Performance of Photocatalytic Hydrogen Evolution

Metal sulfide photocatalysts are typically required during water splitting to produce hydrogen. However, the rapid recombination of photogenerated electron–hole pairs in these highly unstable photocatalysts has restricted hydrogen production to small-scale batch reactions. In this work, porous transition-metal thiophosphites were used to enable continuous long-term hydrogen production through photocatalysis. A wide bandgap (2.04 eV) was essential for generating hydrogen at a rate of 305.6 μmol h⁻¹ g⁻¹, 180 % faster than nonporous FePS₃ nanosheets. More importantly, the high in-plane stiffness of these approximately 7 nm thick porous FePS₃ nanosheets ensured structural stability during 56 h of continuous photocatalysis reactions. The reaction results with D₂O instead of H₂O indicated that hydrogen mainly came from H₂O. Furthermore, a sacrificial reagent (triethylamine) was photodegraded into diethylamine and acetaldehyde through a monoelectronic oxidation process, as indicated by HPLC and LC–MS. This synthesis strategy reported for FePS₃ porous nanosheets paves a new pathway for designing other dianion-based inorganic nanocrystals for hydrogen energy applications.