Exquisite Design of Porous Carbon Microtubule-Scaffolding Hierarchical In2O3-ZnIn2S4 Heterostructures toward Efficiently Photocatalytic Conversion of CO2 into CO

Porous carbon microtubule (PCMT)-scaffolding semiconductor heterostructures were exquisitely designed through growth of ZnIn2S4 (ZIS) ultrathin nanosheets onto In2O3 nanoparticles layers in situ generating on the surface PCMT (abbreviated as PCMT@In2O3/ZIS) toward efficiently photocatalytic conversion of CO2 into CO. The pronounced photocatalytic performance for CO2 photoreduction into CO is attributed to a synergistic effect of the following factors: (1) The multistage hopping of the charge carriers among In2O3, ZIS, and PCMT greatly reduces the charge recombination in In2O3 and ZIS. (2) Mesoporous feature of the PCMT renders the large surface area and abundant active sites to boost to accumulate the local concentration of CO2 in the heterostructures. (3) Existence of large amount of carbon defect in PCMT promotes the activity of absorbed CO2 molecules. (4) The tubular structures with two open ends of PCMT may favor the fast diffusion of the reactants and products, and optical absorption can be also increased by multi-light scattering/reflection in the interior void. (5) The unique fabrication route leads to intimate and tight contact among PCMT, In2O3, and ZIS, which is also favorable for the charge migration. This work makes a contribution to the development of complex hollow photocatalysis system for artificial photosynthesis.