Modifying covalent organic frameworks with MoS2 form Schottky heterojunctions for efficient photocatalytic hydrogen production

Abstract

Covalent organic frameworks (COFs) are endowed with remarkable photoadsorption capabilities, a high specific surface area, and an adjustable photoband structure, and thus have broad application prospects as photocatalysts. However, COFs frequently encounter the issue of severe photogenerated carrier recombination. Therefore, there is an urgent need to develop efficient COF-based heterostructures to improve carrier separation. In this study, a Tp-Tta COF/MoS₂ composite photocatalyst featuring a Schottky heterojunction is ingeniously constructed by coupling MoS₂ nanoparticle electron acceptors with Tp-Tta COF nanosheet electron donors. Kelvin probe force microscopy (KPFM) and X-ray photoelectron spectroscopy (XPS) analyses further confirm efficient electron separation and transfer within the Tp-Tta COF/MoS₂ composite photocatalyst. A unidirectional electron transport channel from Tp-Tta COF to MoS₂ is established at the Schottky interface, and the increase in the local electron density of MoS₂ suppresses electron backflow and promotes charge transfer and separation. As a result, the optimal Tp-Tta COF/MoS₂ photocatalyst exhibits an extraordinarily stable photocatalytic H₂ production rate of 12.50 mmol g⁻¹ h⁻¹, representing a 2.65-fold enhancement compared to Tp-Tta COF alone. This research provides valuable insights and implications for the preparation of Schottky heterojunction catalysts based on Tp-Tta COF, enhancing the kinetics of photocatalytic hydrogen evolution (PHE).