Rational design of dimensionally matched 2D/2D COF based photocatalysts for highly efficient noble-metal-free solar energy catalysis

Abstract

In general, the addition of co-catalysts can effectively solve the problem of severe recombination of photogenerated carriers in two-dimensional (2D) covalent organic framework (COF) materials. However, traditional noble metal and non-precious metal co-catalysts usually suffer from high-cost and dimensional mismatch issues with 2D COFs, respectively. Herein, a range of 2D WS₂/2D TpPa-1-COF (WS₂/TP1C) hybrid materials are successfully constructed via simple solvothermal treatment. In hybrid materials, the addition of 2D WS₂ can effectively improve the light absorption region of the COF materials. More importantly, benefitting from the ultrathin thickness of the WS₂ nanosheets, more surface reactive sites can be formed and the carrier migration distance can be shortened with a higher electron–hole pair migration/separation efficiency, which can be proved by the enhanced photocurrent response, reduced charge transfer resistance and longer carrier lifetime. Consequently, the photocatalytic performance of the COFs can be effectively enhanced with the H₂ production rate up to 4305 μmol g⁻¹ h⁻¹, being about 18.74 times higher than that of pristine COFs, also exceeding those of most of the reported COF based photocatalysts. It is worth noting that the photocatalytic activity of WS₂/TP1C also exceeds that of Pt/TP1C because of a lower hydrogen production potential. This work provides new insights and ideas for developing noble-metal-free COF photocatalysts.