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 FePS ₃ nanosheets. More importantly, the high in-plane stiffness of these approximately 7 nm thick porous FePS ₃ nanosheets ensured structural stability during 56 h of continuous photocatalysis reactions. The reaction results with D ₂ O instead of H ₂ O indicated that hydrogen mainly came from H ₂ O. 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 FePS ₃ porous nanosheets paves a new pathway for designing other dianion-based inorganic nanocrystals for hydrogen energy applications.
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