Z-scheme heterostructure of Cu2O/Pt/NH2-MIL-125(Ti) for photocatalytic CO2 reduction

Abstract

Photocatalytic CO2 and H2O synthesis of alcohols is a promising strategy to address the energy shortage and greenhouse effect. However, its wide application is limited by the rapid recombination of charge carriers. A Z-scheme Cu2O/Pt/NH2-MIL-125(Ti) heterostructure was successfully synthesized in this study. The electrons and holes generated by the photocatalyst can be rapidly separated by the Z-scheme heterostructure. CO2 and H2O are efficiently converted into CH3OH and CH3CH2OH (434.46 and 718.47 µmol g−1). Combined with the electrochemical measurements, the efficient inactivation process is attributed to the enhanced light utilization and the effective suppression of photogenerated charge carrier recombination. The electron-hole transfer pathways and reaction mechanisms are proposed through UV-Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and radical trapping experiments. In addition, several cycling experiments were also carried out, and the composite catalyst showed excellent stability in water. This Z-scheme heterostructure fabrication can sterically suppress the recombination of photogenerated carriers and expand the absorption range, providing a feasible method for photocatalytic CO2 synthesis of high-value chemicals.