Black TiO2 coupled with ZIF-67 for enhanced photocatalytic CO2 reduction to tunable CO/H2 syngas

This study synthesized a composite material of ZIF-67 and black titanium (BT) with high CO 2 reduction capability via a mechanochemical method. Through in-depth analysis of the morphology, structure, optical properties, and electrochemical behavior of the ZIF-67-BT composite photocatalyst, it was confirmed that the composite successfully formed an S-scheme heterojunction structure. This configuration can effectively separate photogenerated charge carriers, resulting in superior CO 2 reduction performance. The findings indicate that the composite material has optimal catalytic performance when the ZIF-67 doping content reaches 30 wt% (30 %ZIF-BT). Within 5 h, 30 %ZIF-BT exhibited excellent photocatalytic activity, with CO and H 2 yields reaching 2486.4 μmol·g −1 and 3495.0 μmol·g −1 , which were 44.0 and 29.4 times greater than the yields of BT, and 2.4 and 1.4 times than ZIF-67. The syngas (comprising CO and H 2 ) generated by ZIF-BT, with an adjustable CO to H 2 ratio ranging from 1:1.40 to 1:2.47, is regarded as a significantly beneficial and crucial intermediate for further conversion into valuable hydrocarbon fuels via Fischer-Tropsch synthesis. This research offers a feasible method to construct S-scheme heterojunction in ZIF-BT composite materials.