Pd single atoms cooperate with S vacancies in ZnIn2S4 nanosheets for photocatalytic pure-water splitting

Photocatalytic water splitting has emerged as a new frontier for converting solar energy to green H-2 and value-added chemicals. Nevertheless, great challenges still remain for developing efficient photocatalysts for pure water splitting without sacrificial agents. In this work, we demonstrate that doping hexagonal ZnIn2S4 (ZIS) with Pd single atoms (Pd-0.03/ZIS) can serve as a highly efficient photocatalyst for pure water splitting to simultaneously produce H-2 and H2O2 without any sacrificial agents. Results from aberration-corrected high-angle annular dark field scanning transmission electron microscopy, X-ray fine spectroscopy, in-situ electron paramagnetic resonance and diffuse Fourier transform infrared spectroscopy reveal that doping ZIS with Pd single atoms facilitates the formation of S vacancies (S-v), where the photogenerated electrons can transfer to Pd single atoms, as a result of enhanced separation of electron-hole pairs and improved photocatalytic performance. Impressively, Pd-0.03/ZIS displays a stoichiometric ratio of H-2 and H2O2 with the productivity of 1,037.9 and 1,021.4 mu mol g (-1) h (-1), respectively, which has largely outperformed pure ZIS and other reported catalysts for pure water splitting. This work provides an efficient photocatalyst for water splitting to produce H-2 and H2O2, which may attract rapid interest in materials science, chemistry, and heterogeneous catalysis.