Oxidation State and Heterointerface Co-Engineered Carrier Dynamics in POM@MOF Systems for Enhanced Photocatalytic Performance

Optimizing carrier dynamics to elevate photocatalytic efficiency represents a central goal in the design of photocatalysts; however, achieving this remains a daunting challenge within the research community. In this study, we have devised and synthesized four types of intramolecular heterojunctions (POM@MOFs), constructed by integrating polyoxometalates (POMs) with metal–organic frameworks (MOFs). Specifically, we utilized an organic linker featuring a photosensitive phenothiazine core with incrementally oxidized sulfur sites, and employed Zn/Cd as the metal nodes to create four analogous POM@MOF composites, designated as SO x -M ( x =  1, 2; M = Zn, Cd). Through strategic heterointerface engineering, we have achieved a synergistic improvement in both the generation and separation efficiency of charge carriers within these materials. Our results demonstrate that the SO 2 -M series, which incorporates phenothiazine in a more oxidized state (-SO 2 -), surpasses the SO-M series (-SO-) in terms of charge carrier generation and separation efficiency. Furthermore, within the SO 2 -Cd , the covalent bonds connecting the MOF and POM components significantly facilitate the separation and migration of photogenerated electrons. This collaborative regulatory mechanism enables SO 2 -Cd to exhibit outstanding photocatalytic performance. This research introduces a pioneering approach for the cooperative modulation of oxidation states and heterointerface interactions, offering a promising pathway for the development of highly efficient photocatalysts.