<i>In situ</i>growth of lead-free halide perovskites into SiO₂sub-microcapsules toward water-stable photocatalytic CO₂reduction

Abstract

Halide perovskites (HPs) are highly susceptible to heat, light, or moisture and are easily decomposed even in an ambient environment, which greatly hinders their practical applications. Herein, an <i>in situ</i> growth strategy is presented for implanting an inorganic lead-free HP, Cs₂AgBiBr₆, into SiO₂ sub-microcapsules to form a Cs₂AgBiBr₆@SiO₂ yolk-shell composite. The SiO₂ sub-microcapsule endows Cs₂AgBiBr₆ with good thermal and light stability, as well as excellent corrosion resistance against polar solvents. Furthermore, when employed as a lead-free perovskite photocatalyst, the composite exhibits a higher visible-light-driven CO₂-to-CO rate (271.76 μmol g^-1 h^-1) and much better stability than Cs₂AgBiBr₆ in water. The formation of a Cs₂AgBiBr₆/SiO₂ heterostructure using an <i>in situ</i> growth method alleviates water binding on the perovskites, supported by density functional theory calculations, which is the key to an improvement in the stability of the composite. The <i>in situ</i> growth strategy developed here sheds light on the design and development of HP-based materials for applications involving polar solvents.