2D/2D COF/MOF S-Scheme heterojunction boosts photocatalytic H2 evolution

Abstract

Covalent organic frameworks (COFs) hold great promise for photocatalysis; however, their activity for photocatalytic hydrogen evolution is frequently hindered by the critical limitation of rapid charge recombination. Herein, we report an S-scheme MOF/COF heterojunction synthesized through a facile in-situ growth approach. This architecture was evaluated for its photocatalytic hydrogen production performance. This innovative S-scheme heterojunction architecture synergistically improves light harvesting, enhances redox capability, and facilitates effective separation and transport of photogenerated charge carriers and exciton dissociation, thus significantly boosting photocatalytic hydrogen evolution activity. Under optimal conditions, the COF/MOF S-Scheme heterojunction exhibits a maximum photocatalytic hydrogen production rate of 276.01 mmol g⁻¹ h⁻¹, representing a 2.24-fold improvement over the parent COF. Comprehensive mechanistic studies, including in-situ XPS and femtosecond transient absorption spectroscopy, elucidate the S-scheme charge transfer pathway and promote charge separation dynamics, while the strategic integration of Ni metal nodes with Pt cocatalysts simultaneously optimizes charge transfer and active sites. These findings offer valuable insights for precisely designing various kinds of COF-based S-scheme heterojunctions, advancing sustainable solar-to-hydrogen energy conversion.