Remarkable photoexciton enhancement induced by heterogeneous facet engineering for benchmark CO2 photothermal reduction

A heterogeneous facet coupled with a metal strategy was proposed to suppress random electron scattering, enabling sufficient photoexciton concentration and efficient charge migration, which led to a benchmark CO generation rate of 1.87 mmol g −1 h −1 . Developing effective strategies to modulate carrier concentration and migration is crucial for advancing photocatalysis. In this study, we pioneer that the built-in electrical field (BIEF), induced by heterogeneous facet engineering, can efficiently promote photoexciton concentration and enhance carrier mobility. As a proof-of-concept, hetero-faceted MOFs coupled with noble metals were successfully constructed via a novel water modulation strategy, where water served as a “Ti 4+ release capsule” for precise crystal facet control. The resulting hetero-facets established a tailorable BIEF, which facilitated efficient transfer of thermally excited electrons and significantly enhanced photoexciton concentration. The optimized Pd/t-MUV-10 catalyst achieved an unprecedented CO production rate of 1.87 mmol g −1 h −1 was achieved via photothermal conversion of CO 2 and H 2 O, representing a 21-fold enhancement over Pd, which surpassed all previously reported photothermal catalysts. In situ characterizations and theoretical calculations further confirmed that facet-induced BIEF effectively suppressed random electron scattering, modulated electron distribution, increased photoexciton concentration, and thereby boosted catalytic activity. These findings establish facet engineering as a novel paradigm for modulating carrier concentration, providing new insights into the design of efficient photothermal catalytic systems.