Modular integration of photoactive units in hafnium-based metal-organic frameworks for photocatalytic carbon dioxide reduction and hydrogen peroxide production

The simultaneous optimization of charge dynamics and catalytic active sites is a key challenge in designing multifunctional photocatalysts. We have developed a modular integrated strategy to construct bifunctional metal-organic frameworks (MOFs) for photocatalytic CO₂ reduction and H₂O₂ generation. The MOFs integrated an Hf₆ cluster as the catalytic center, a tetrakis(4-carboxyphenyl)porphyrin (TCPP) unit as the light-harvesting component, and 2-aminoterephthalate (BDC-NH₂) as the electron-transfer medium. Notably, the optimized photocatalyst (Hf-TCPP-UiO-66-NH₂, UiO = University of Oslo) achieved a CO₂-to-CO conversion rate of 172.9 μmol g^-1 h^-1 and an H₂O₂ production rate of 158.1 μmol g^-1 h^-1 in simulated seawater. To further clarify the structural characteristics and catalytic reaction mechanism of the bifunctional MOFs, the projected density of states (PDOS) and differential charge density (DCD) were calculated using density functional theory (DFT). This work presents a generalizable paradigm for integrating photon absorption, charge transport, and catalytic reactions by structurally modular design single MOFs, thereby offering new pathways for solar-driven chemical synthesis beyond traditional single-function systems.