Photocatalytic CO2 reduction to CH4 on iron porphyrin supported on atomically thin defective titanium dioxide

Photocatalytic CO2 reduction to CH4 is a promising strategy to solve the greenhouse effect and energy shortage problems. However, its application has been restricted by its low efficiency and poor selectivity. Herein, atomically thin defective TiO2 is modified with iron tetraphenylporphyrin (FeTPP) to reinforce the selectivity of CO2 reduction. The synthesized Fe-TiO2-x photocatalyst exhibits a CH4 production rate of 20.48 μmol g−1 h−1 and a CH4 selectivity of 56.1% under visible light irradiation. Oxygen vacancies (OVs) of defective TiO2 contributed to visible light absorption and FeTPP dispersion. The presence of FeTPP enhances the adsorption of CO intermediates, promoting the CH4 selectivity. The conduction band of Fe-TiO2-x lowers, inhibiting the CO generation. During the photoconversion process, CO2˙− and COOH− intermediate products were detected by in situ DRIFTS. The synergistic effect of OVs and FeTPP improves the efficiency and selectivity of CO2 photoreduction to CH4. This work offers a new insight towards designing a photocatalyst for photoreduction of CO2 to CH4.