In-situ Self-transformation Synthesis of N-doped Carbon Coating Paragenetic Anatase/Rutile Heterostructure with Enhanced Photocatalytic CO2 Reduction Activity

Photocatalytic CO2 reduction can reduce greenhouse gas emissions and convert CO2 into value-added chemical feedstocks and fuels. P25 is one of the most popular photocatalyst, but its high photoinduced charge recombination rate and low CO2 adsorption ability hinder its application in photocatalytic CO2 reduction due to the limited anatase/rutile interface and small specific surface area. Herein, a paragenetic anatase/rutile interface is in-situ formed in one crystal grain via calcination of NH2-MIL-125 in argon atmosphere and the obtained N doped porous carbon layer endows its high specific surface area. The in situ XRD and HRTEM characterization proved the anatase/rutile interface is in situ formed by the phase transformation from anatase (211) plane to rutile (211) plane. The charge separation efficiency of the photocatalyst with N-doped carbon coating paragenetic heterostructure is proved to be enhanced compared with N-doped carbon coating anatase or rutile single phase catalyst. The optimized catalyst S-750Ar with paragenetic anatase/rutile structure shows a 7.6 folds enhanced CO conversion rate than that of P25. These findings provide an in-situ self-transition strategy to regulate charge transfer between phases at the interface and promote the application of heterogeneous catalysts.