Activating surface sulfur atoms via subsurface engineering toward boosted photocatalytic water splitting

The performance of photocatalysts is affected not only by the surface structure but also by the atomic arrangement of the subsurface. Guided by first-principle simulation, Pt(Pd) single atoms are introduced into hexagonal ZnIn2S4 to substitute the middle In site, and dual S vacancies in the vicinity of the dopant are subsequently created. This unique subsurface dopant-vacancy pair brings a new defect level and higher hole concentration, resulting in enhanced charge separation efficiency and superior electronic conductivity. More importantly, it could also modulate the p-band center of neighboring surface S atoms, thus optimizing the balance between H adsorption and desorption. As a consequence, the subsurface-engineered ZnIn2S4 delivers an H2 evolution rate of 165.4 μmol h−1 under visible-light irradiation, and a great number of H2 bubbles are released under natural solar light. This work provides a new perspective on the development of solar-to-H2 conversion through artful subsurface engineering.