Perovskite Nanocrystals In Situ Encapsulated in TiO₂ Microspheres for Stable CO₂ Photoreduction in Water

Photoreduction of carbon dioxide (CO₂) into fuels presents a promising approach to mitigate global warming and energy crises. Halide perovskite nanocrystals (NCs) with prominent optoelectronic properties have triggered substantial attention as photocatalysts but are limited by the charge recombination and instability. Here, we develop stable CsPbBr₃/titania microspheres (TMs) by in situ growth of CsPbBr₃ NCs inside mesoporous TMs through solid-state sintering, which significantly improves the stability of perovskite NCs, making them applicable in water with efficient CO₂ photoreduction performance. Notably, the CsPbBr₃/TMs demonstrates a 6.73- and 9.23-fold increase in the rate of CH₄ production compared to TMs and CsPbBr₃, respectively. The internal electric field facilitates S-scheme charge transfer, enhancing the separation of electron-hole pairs, as evidenced by X-ray photoelectron spectroscopy and electron paramagnetic resonance analysis, which is pivotal for the selective photoreduction of CO₂. These insights pave the way for the design of CsPbBr₃-based photocatalysts with superior efficiency and stability.