Energy band modulating of NiO/BiOCl heterojunction with transition from type-II to S-scheme for enhancing photocatalytic CO2 reduction

The photo-driven CO 2 reduction holds significant potential in facilitating carbon fuel conversion. However, the inefficiency of charge conversion severely limits its spractical applications. Herein, the charge transfer routeway was tailored in NiO/BiOCl-7 heterostructures via a transform from type-II to S-scheme for enhancing CO 2 photoreduction to CO. Such S-scheme NiO/BiOCl-7 heterojunctions were prepared by pH-modulation to optimize the energy band structure of BiOCl and introduce abundant oxygen vacancies. Surprisingly, the S-scheme NiO/BiOCl-7 heterojunctions exhibited a significantly enhanced production of CO (78.11 μmol·g −1 ·h −1 ) with an impressive selectivity of 97.1 %, representing a remarkable 1.7- and 4.3-fold improvement in CO yield compared to the type-II NiO/BiOCl heterojunctions and pure BiOCl samples, respectively. The in-situ spectral experiments and DFT calculations reveal that the superior CO production can be attributed to a lower energy barrier for COOH* and a smoother potential energy surface of the S-scheme heterojunction with abundant oxygen vacancies. This meticulous strategy of energy band modulation sheds light on the deliberate customization of Bi-based heterostructures with favorable charge transfer for highly effecient photocatalysis.