Enhanced Solar-to-Hydrogen Conversion and Hydrogen Isotope Separation through Interfacial Hydrogen-Bond Engineering and Homolytic O–H Cleavage on Multianionic Sulfides in Large-Scale Floating Nanocomposites

Hydrogen-atom transfer (HAT) is crucial for selective photocatalytic water splitting. We report a class of metal chalcogenide catalysts (CdxZn1–xS(OH)-SH) that feature mercapto groups (acid sites) and lattice oxygens/hydroxyls (base sites) to form acid–base pairs. Based on this structural design, we demonstrate lattice oxygen/hydroxyl activation and an HAT process under light irradiation and identify a rapid hydrogen-transfer pathway governed by the Grotthuss mechanism. The photocatalyst Cd0.5Zn0.5S(OH)-SH exhibited a rate of 205.8 mmol·g–1·h–1 under full-spectrum illumination and an apparent quantum efficiency of 12.4% at 420 nm without any cocatalyst. Based on the HAT process, this novel catalyst achieves a proton–deuteron separation factor of approximately 11. The energy consumption is projected to be orders of magnitude lower than that of existing technologies. The fabricated large-scale nanocomposites of these photocatalysts are expected to enable large-scale separation of substantial volumes of diluted tritium wastewater.