In situ construction of Schottky junctions on MOF-derived defective TiO2 oval nanocages for enhanced photocatalytic CO2 reduction

Designing and preparing efficient photocatalysts for CO2 reduction remains a significant challenge. Herein, Cu/TiO2 oval nanocage Schottky junctions with surface defects (oxygen vacancies) were obtained using oval-like MIL-125(Ti) particles as precursor through a solvothermal reaction and subsequent hydrogenation treatment. In this synthetic process, the growth and aggregation of Cu nanoparticles were inhibited by the microporous structure and the oxygen-insulating hydrogenated environment of MIL-125(Ti), resulting in highly dispersed Cu nanoparticles on the defective TiO2 oval nanocages. The optimized catalyst (8Cu/H-TiO2) achieves a remarkable CO2 photoreduction performance, and the CO yield reaches up to 135 μmol g-1·h-1, representing 2.5 times more than that of bare TiO2 (54 μmol g-1·h-1). The enhanced photocatalytic performance benefits from the combined effects of Schottky junctions, oval hollow structure, and oxygen vacancies. The formed Schottky junctions greatly enhanced charge separation efficiency. The anchored Cu nanoparticles and surface defective mesoporous structure provide abundant active sites and high CO2 adsorption capacity, facilitating the enhancement of reaction rate. Our study demonstrates a straightforward and promising method for producing highly efficient MOF-derived catalysts in photocatalysis applications.