BiOCl for efficient visible light photocatalytic CO2 reduction with abundant oxygen vacancies and WO3 as p-n heterojunctions

The development of highly efficient photocatalysts is important for CO2 reduction. In this work, bismuth oxychloride (BiOCl) nanospheres with exposed (110) crystalline surfaces were prepared via the coprecipitation method. Oxygen vacancies (OVs) were generated on the nanosphere surface by adjusting the solution pH. The final product obtained is BiOCl with abundant oxygen vacancies (BiOCl-x). Interfacial OVs have importance in terms of narrow bandgap. WO3 nanotubes were introduced during the growth of BiOCl crystals, and closely contacted WO3 nanotube–loaded BiOCl nanomicrospheres were obtained (WO3/BiOCl-x). The WO3/BiOCl-x photocatalyst showcased a substantial increase in CO production, reaching 27.3 µmol·g−1, which indicates a 2.7-fold improvement compared with that of pure BiOCl. The photocatalytic CO2 reduction efficiency of BiOCl improved by combining OVs with p–n heterojunctions, which modulated the energy band structure of BiOCl and increased its photogenerated carrier mobility. This work provides some motivation for exploiting the synergy between defect engineering and heterojunctions to increase the activity of bismuth-based photocatalysts.