Defect-mediated hierarchical tubular CoSe2@TiO2 heterostructure photocatalysts for boosted CO2 photoreduction

Abstract

The creation of effective photocatalysts plays a crucial role in transforming CO2 into valuable chemical feedstocks, yet single component photocatalysts generally suffer from inadequate electron-hole pair separation, poor CO2 adsorption capacity, and low visible light absorption. Herein, defect-mediated hierarchical CoSe2@TiO2 heterostructure nanotubes have been skillfully designed and fabricated as highly efficient and stable photocatalysts for CO2 photoreduction, with CoSe2 and TiO2 functionally acting as reduction and oxidation sites, respectively. To this end, CoSe2 nanotubes were first prepared from the selenization of Co(CO3)0.35Cl0.20(OH)1.10 nanorod precursor. Then amorphous TiO2 nanoparticles were coated on the CoSe2 nanotubes. The final hydrothermal treatment in ethylenediamine solution makes amorphous TiO2 nanoparticles transform into amine-functionalized anatase TiO2 nanosheets with abundant oxygen vacancy defects, leading to the formation of defect-mediated hierarchical CoSe2@TiO2 nanosheet nanotubes. In this tubular heterostructure catalyst, the hollow tubular cavities covered with amine-modified nanosheets expose more active sites to trigger CO2 adsorption and activation. Moreover, the oxygen vacancy defect-mediated heterostructure enhanced charge separation efficiency, incident light utilization, and surface reduction-oxidation kinetics. Benefiting from these advantages, the optimized composite photocatalyst demonstrated remarkable performance in CO2 reduction, achieving a high CO yield (71.71 μmol g-1 h-1) and excellent stability. This study offers some insights into the efficient design approach to construct heterojunction catalysts for photocatalytic applications.