Spatial distribution of ZnIn2S4 nanosheets on g-C3N4 microtubes promotes photocatalytic CO2 reduction

• A kind of spatial distribution heterojunction based on g-C 3 N 4 microtubes. • In situ growth of ZnIn 2 S 4 nanosheets on g-C 3 N 4 microtubes. • Microstructure of heterojunction greatly affects photocatalytic CO 2 reduction. • Spatial distribution heterojunction is superior to bulk or 2D/2D heterojunction. The graphitic carbon nitride (g-C 3 N 4 ) is regarded as a powerful support for constructing heterojunction. How to rationally design high-performance g-C 3 N 4 -based heterojunction remains a great challenge. In this work, a kind of spatial distribution heterojunction is prepared by in situ growing ZnIn 2 S 4 (ZIS) nanosheets on g-C 3 N 4 microtubes (T-CN). To highlight the advantage of such a structure design, g-C 3 N 4 bulk (B-CN) and g-C 3 N 4 nanosheets (S-CN) are also used as the supports to obtain B-CN/ZIS bulk heterojunction and S-CN/ZIS 2D/2D heterojunction, respectively. T-CN/ZIS spatial distribution heterojunction combines the hierarchical core/shell structure of B-CN/ZIS and ultrathin structure of S-CN/ZIS, which is much favorable for photocatalytic CO 2 reduction. It is found that the gas yield from CO 2 reduction is highest over T-CN/ZIS, which is 3.5 and 1.5 times higher than B-CN/ZIS and S-CN/ZIS. The experimental results manifest that the spatial distribution of ZIS nanosheets on T-CN induces stronger photoabsorption, faster interfacial charge transfer, and larger CO 2 adsorption, all of which are responsible for the best catalytic activity. It is expected that this work will provide an instructive guideline for designing g-C 3 N 4 -based heterojunction.