Enhanced Photocatalytic CO2 Reduction to Methanol over Eco-Friendly CuCo-ZIF@g-C3N4 Synthesized from Recyclable Resources

The present work is focused on designing a sustainable catalyst for the photocatalytic conversion of CO2 to methanol under visible light irradiation. Notably, most catalysts are made of costly, nonearth-abundant metal resources, which can partially hinder the large-scale implementation of CO2 utilization efforts. Thus, a highly efficient CuCo-ZIF@g-C3N4 composite photocatalyst was prepared using copper sulfate (CuSO4) and cobalt sulfate (CoSO4) recovered from mining waste. Notably, the resulting composite offers enhanced photocatalytic activity relative to the individual CuCo-ZIF and graphitic carbon nitride (g-C3N4) building blocks during CO2 assessed separately. Also, the catalyst's morphology, structure, and photoelectrochemical characteristics were accessed, and the photocatalytic mechanism and synergy between the composite components were systematically explored. The catalytic process was optimized via response surface methodology, dramatically improving the initial methanol yield from 1018.65 μmol/gcat to an impressive 1876.8 μmol/gcat with an apparent quantum yield of 0.139%. The results from this study provide insight into the application of sustainable resources for CO2 photoreduction.