TiO/CsPbBr S-scheme heterojunctions with highly improved CO photoreduction activity through facet-induced Fermi level modulation.

Photocatalytic CO reduction is a promising method to resolve the energy shortage problem. Developing photocatalysts with strong redox capabilities is urgently needed to achieve high photocatalytic activity. Herein, we synthesized TiO/CsPbBr S-scheme heterojunctions with modulated internal electric field by facet engineering of TiO to control charge transfer for improved photocatalytic activity. Density functional theory (DFT) calculation reveals that there is a wider Fermi level difference between TiO-(101) and CsPbBr than that between TiO-(001) and CsPbBr, which will induce more obvious band bending. Subsequently, more efficient spatial separation will occur around the interface. Thus, TiO-(101)/CsPbBr heterostructures effectively reduce CO into CO with the selectivity of 90.2 % and reduction rate of 12.5 μmol h, 15.6 and 5.6 times improvement than that of 101-TiO and TiO-(001)/CsPbBr, respectively. This report proposes a feasible idea of employing facet engineering to take the advantage of S-scheme heterojunction.