Metal halide perovskite nanocrystals, e.g., CsPbBr₃ nanocrystals, are promising catalysts for photocatalytic CO₂ reduction due to their excellent optical properties. However, their photocatalytic performance is still low due to poor charge separation, severe charge recombination, and a narrow solar-spectrum response.

Zhengquan Li, Zhejiang Normal University, China, Enyi Ye, A*STAR (Agency for Science, Technology and Research), Singapore, Licheng Sun, Westlake University and Westlake Institute for Advanced Study, Hangzhou, China, and colleagues have developed an approach to creating a CsPbBr₃/WO₃ heterojunction for boosting charge separation and light-harvesting to achieve highly efficient photocatalytic CO₂ reduction under visible-light and near-infrared (NIR) irradiation.

The team used O-defective WO₃ nanosheets as substrates for the growth of CsPbBr₃ nanocrystals (pictured). They first prepared WO₃·H₂O nanosheets via a solvothermal method and treated them at 300 °C under a reducing atmosphere to produce oxygen vacancies.

The hybrid photocatalyst showed excellent activity toward CO₂ reduction, about seven-fold higher than pristine CsPbBr₃ nanocrystals. Interestingly, the developed CsPbBr₃/WO₃ heterojunction can also effectively utilize the stored electrons in the O-defective states of WO₃ nanosheets, resulting in a sound photocatalytic CO₂ reduction under infrared-light irradiation, which is very rare for photocatalytic CO₂ reduction. The work could be useful for the development of novel, efficient, and stable composite photocatalysts that can harvest the solar spectrum as broadly as possible.

• In Situ Generating CsPbBr₃ Nanocrystals on O‐defective WO₃ as Z‐scheme and NIR‐responsive Heterojunctions for Photocatalytic CO₂ Reduction,
  Xinyan Jiang, Yunxuan Ding, Song Zheng, Yinglin Ye, Zhengquan Li, Liyun Xu, Jin Wang, Zibiao Li, Xian Jun Loh, Enyi Ye, Licheng Sun,
  ChemSusChem 2021.
  https://doi.org/10.1002/cssc.202102295