Porphyrin-Based Carbon Dots for Efficient Photocatalytic Reduction of CO2 to Methanol

Photocatalytic CO2 reduction to solar fuel is a potential way to overcome the problem of high carbon dioxide concentrations; however, the process still faces enormous challenges, such as the low light absorption efficiency and high carrier recombination rates. This work synthesized tetraphenylporphyrin-based carbon dots (TPP-CDs) for the photocatalytic CO2 reduction to CH3OH under simulated sunlight to extend the absorption region of the CDs. The conduction band of the TPP-CDs has a sufficiently negative reduction potential to reduce CO2. TPP-CDs containing 1 wt.% TPP achieved an optimum CH3OH production rate of 173.35 μmol·gcat-1·h-1, with a remarkable 2.06-fold increase compared to pristine CDs without TPP. In this study, TPP-CDs were synthesized by changing the CD precursors to improve the utilization of visible light and apply them to the photocatalytic reduction of CO2.