Schottky-assisted S-scheme heterojunction photocatalyst CdS/Pt@NU-1000 for efficient visible-light-driven H2 evolution

Abstract

Coupling metal-organic frameworks (MOFs) with inorganic semiconductors to construct S-scheme heterojunction photocatalysts is an effective way to facilitate photocarriers transfer and separation, as well as enhance redox ability for photocatalytic water-splitting into H2. However, the poor electrical conductivity of MOFs, fast recombination of photogenerated electron-hole pairs, and slow surface redox reaction rates on photocatalysts lead to inefficient consumption of all charge carriers thus impeding further improvement of photocatalytic activity. Thus, optimizing the separation, transfer, and utilization efficiencies of interfacial charge carriers in MOFs-based S-scheme heterojunction may pave the way for achieving excellent photocatalytic activity. Herein, a novel Schottky-assisted S-scheme heterojunction photocatalyst CdS/Pt@NU-1000 was prepared by the combination of Pt-embedded NU-1000 with CdS. The optimized photocatalyst CdS/0.7Pt@NU-1000 exhibits the highest visible-light-driven H2 evolution rate with 3.604 mmol g–1 h–1, which is 12.7 and 18.8 folds of that for single CdS and NU-1000, respectively. The splendid photocatalytic performance benefited from the broadened light absorption, and the synergistic effect of the formed Schottky junction and S-scheme heterojunction. Furthermore, the formation of the S-scheme system was validated by density functional theory (DFT) calculations, in-situ irradiated X-ray photoelectron spectroscopy (ISI-XPS), and electron paramagnetic resonance (EPR) test. This work can provide some guidance for the design of efficient heterojunction photocatalysts by optimizing interfacial charge transfer.