Interfacial Oxygen Vacancy Engineered Two-Dimensional g-C₃N₄/BiOCl Heterostructures with Boosted Photocatalytic Conversion of CO₂

The CO2 conversion by photocatalysis has been a focus of global concern as yet, and the exploring of efficient heterostructures is critical to promote the photocatalytic performance. However, the weak interface contact largely limits the photogenerated carrier transfer and restrains the activities of heterostructures. In this work, two-dimensional (2D) g-C3N4/BiOCl heterostructures were exemplified to demonstrate a facile strategy of interfacial oxygen vacancies (IOVs) with enhanced interfacial interaction to promote the photocatalytic conversion of CO2. Both experimental results and density functional theory calculations determined that the IOVs can provide a transport channel for the interfacial carriers, leading to a built-in electric field from g-C3N4 to BiOCl and a Z-scheme type for IOVs-introduced g-C3N4/BiOCl heterostructures, which largely promoted the photogenerated carrier transfer efficiency. This further induced the generation of more electrons to participate in the surface reactions and significantly reduced the energy barriers for the CO2 reduction, especially facilitating the decomposition of intermediate COOH into CO. As a result, the photocatalytic activity of IOVs-introduced g-C3N4/BiOCl heterostructure for the conversion of CO2 to CO was enhanced by 1.6 times compared to pristine g-C3N4/BiOCl. This work could provide insights into the important role of oxygen vacancies in boosting the reduction activity of CO2 for the heterojunctions and provide a facile route for designing highly efficient 2D heterostructures in the field of photocatalysis.