Metal-organic framework-derived three-dimensional CoSe2/Cd0.8Zn0.2S Schottky junction for highly efficient photocatalytic H2 evolution

The well-designed interface plays a key role in enhancing the charge transfer kinetics. In this work, a threedimensional CoSe2/Cd0.8Zn0.2S Schottky junction was successfully prepared using zeolitic imidazolate framework-67 (ZIF-67) as precursor material by in-situ chemistry synthetic strategies to improve the charge transfer kinetics. The photocatalytic H2 generation rate of 3.2%-CoSe2/Cd0.8Zn0.2S is 80 times higher than pristine Cd0.8Zn0.2S. The systematic characterization (XPS, TRPL, EPR, etc.) and DFT results show the improvement of photocatalytic performance derives from the formation of Schottky junction between CoSe2 and Cd0.8Zn0.2S. The well-designed and tight interface can facilitate electrons transfer from Cd0.8Zn0.2S to CoSe2, and Schottky barrier can suppress the electrons flow back to Cd0.8Zn0.2S, resulting in the high separation of charge carriers. On the other hand, the noble metal-free CoSe2 with larger specific surface area function as the electron acceptors and active sites for reducing H+ to H2 efficiently, thus in favor of obtaining the enhanced H2 generation performance. Combining the three-dimensional structure with Schottky junction, this work provides an effective strategy to prepare photocatalysts.

Automated summary

A well-designed interface plays a crucial role in improving charge transfer kinetics. In this study, a three-dimensional CoSe2/Cd0.8Zn0.2S photocatalyst with a Schottky junction was successfully synthesized using zeolitic imidazolate framework-67 (ZIF-67) as the precursor material. The photocatalytic H2 generation rate of 3.2%-CoSe2/Cd0.8Zn0.2S is 80 times higher than that of pristine Cd0.8Zn0.2S. Characterization techniques (XPS, TRPL, EPR, etc.) and DFT calculations reveal that the improved photocatalytic performance is attributed to the formation of a Schottky junction between CoSe2 and Cd0.8Zn0.2S. The well-designed interface facilitates electron transfer from Cd0.8Zn0.2S to CoSe2, while the Schottky barrier suppresses electron backflow, leading to efficient charge carrier separation. Additionally, the noble metal-free CoSe2 with a larger specific surface area acts as an electron acceptor and active site for efficient reduction of H+ to H2, contributing to the enhanced H2 generation performance.