In-situ directional growth of NH2-MIL-125(Ti) induced by diatomite enhances the quantum efficiency of CO2 photoreduction with water vapor

Photocatalytic CO 2 reduction harnesses sunlight to convert CO 2 into fuels (e.g., CO, CH 4 ) to address global warming and energy shortages, but faces challenges like high cost and low efficiency. In this work, NH 2 -MIL-125(Ti)/diatomite composites were prepared by one-step solvothermal method using diatomite as a support. Characterization indicated that NH 2 -MIL-125(Ti) units were grown in-situ on diatomite through surface-mediated interactions with Si-O-Ti bonds. This process significantly reduced the agglomeration of NH 2 -MIL-125 particles. Among the resulting composites, NH 2 -MIL-125/DE-60 % had the best photocatalytic activity with a CO production rate of 7.36 μmol g −1 h −1 , which is 1.56 times higher than NH 2 -MIL-125. In four cycles, the yield remained above 6.88 μmol g −1 h −1 . Meanwhile, electrochemical characterization revealed that composite enhances the separation efficiency of photogenerated carriers and reduces carrier migration resistance. The excellent performance of NH 2 -MIL-125/diatomite composites could be attributed to the synergistic effects of its better dispersion and the Si-O-Ti interface formation, which improve light absorption, increase the number of active sites and facilitate charge separation. Meanwhile, the specific mechanism of CO 2 reduction by NH 2 -MIL-125/diatomite composites and its reduction pathway were also revealed. In conclusion, this study successfully reduced the agglomeration effect of MOFs, and provided implications for realizing in-situ growth of MOFs on mineral surfaces.