Synergistic effect of excellent carriers separation and efficient high level energy electron utilization on Bi3+-Ce2Ti2O7/ZnIn2S4 heterostructure for photocatalytic hydrogen production

The separation of photogenerated carriers and the efficient utilization of high-level energy electrons (HLEEs) are the key processes for improving the performance of photocatalysts. Herein, Ce2Ti2O7/ZnIn2S4 (CTOZIS) and Bi3+-doped Ce2Ti2O7/ZnIn2S4 (BCTOZIS) photocatalyst were successfully synthesized through hydrothermal method. The photocatalytic hydrogen production of CTOZIS and BCTOZIS was 1233.7 μmol g−1 and 4168.5 μmol g−1 under visible light irradiation (λ ≥ 420 nm) within 5 h, which was 2.3 and 7.6 times than that of pure ZnIn2S4, respectively. X-ray photoelectron spectroscopy, photoluminescence spectroscopy and electrochemical characterization demonstrated that after Bi3+ doping, the electron-hole pairs recombination of BCTOZIS was inhibited, which may be ascribed to the establishment of a Z-scheme heterojunction and the presence of oxygen vacancy and Ce4+/Ce3+ redox center. The doping of Bi3+ resulted in the adjustment of the valence band position of Ce2Ti2O7 from 1.98 V to 1.92 V. This adjustment enabled direct transfer of HLEEs generated in Ce2Ti2O7 to the conduction band of ZnIn2S4 for hydrogen production with a wavelength below 423 nm. The synergistic effect of conventional Z-scheme electron transfer and the unique utilization of HLEEs boosted the photocatalytic performance of BCTOZIS. This study affords an innovative insight for designing visible-light-driven photocatalysts with high photocatalytic activity.