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

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 CO2 reduction sites. Herein, non-noble metal catalysts of TiO2 nanotubes (TNT) and hexagonal ZnIn2S4 nanosheets (ZIS) have been synthesized by simple hydrothermal methods and used for photoreduction of CO2. After optimizing the TNT-loading ratio on ZIS, 10 wt.% TNT/ZIS showed the best CO production activity (4.41 mmol g–1h−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 CO2 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)32+ cocatalyst, in which Co(bpy)32+ can be reduced to Co(bpy)3+ and re-oxidized to its original oxidation state during CO2 conversion.