Construction of 1D TiO2 nanotubes integrated ultrathin 2D ZnIn2S4 nanosheets heterostructure for highly efficient and selective photocatalytic CO2 reduction

• An efficient TNT/ZIS heterostructure is designed for CO 2 photoreduction. • CO production rate of TNT/ZIS is 4.41 mmol g −1 h −1 , which is 1.5 times improved. • The co-catalyst Co(bpy) 3 2+ plays an important role in efficiency and selectivity. • TNT/ZIS is stable for up to 72 h under solar light irradiation. • Detailed mechanism was investigated through spectroscopy and elemental analysis. Development of low cost, highly efficient and non-noble metal photosystem is of a great significance for promoting the photoproduced carrier’s separation and acting as CO 2 reduction sites. Herein, non-noble metal catalysts of TiO 2 nanotubes (TNT) and hexagonal ZnIn 2 S 4 nanosheets (ZIS) have been synthesized by simple hydrothermal methods and used for photoreduction of CO 2 . After optimizing the TNT-loading ratio on ZIS, 10 wt.% TNT/ZIS showed the best CO production activity (4.41 mmol g –1 h −1 ), which was 1.5 times higher than CO production rate of pristine ZIS. Especially, TNT/ZIS can present a stable CO evolving tendency during 72 h irradiation, producing regular activity and selectivity for 4 times of recycling test under solar-light irradiation. To reveal the underlying photocatalytic mechanism, the crystal structure, nanomorphology, light absorption, energy bandgap, element component and electrochemical behaviors of those obtained composite was characterized and analyzed. The results indicate that TNT/ZIS composite with glorious CO 2 reduction activity not only extends the responsive spectral range, but also pushed the transfer and separation of photoexcited electrons from ZIS to TNT and then to Co(bpy) 3 2+ cocatalyst, in which Co(bpy) 3 2+ can be reduced to Co(bpy) 3 + and re-oxidized to its original oxidation state during CO 2 conversion.