Characterizations of Heterojunction Photocatalysts with Perovskite and Tin Sulfide Nanocrystals for Photocatalytic CO₂ Reduction

Nanocrystal–nanocrystal heterojunctions play a prominent role in tuning the optical properties of materials to attain desired functionalities. In the realm of perovskite heterojunctions for photocatalysis, coupling between two nanocrystals is less explored, as perovskite nanocrystals were predominantly coupled with 2D sheets. Herein, we report the synthesis and photocatalytic activities of cesium formamidinium lead bromide (CF) perovskite nanocrystal heterojunctions with tin(II) sulfide (SnS) nanocrystals. Thorough structural, morphological, and charge transport dynamics studies were presented to confirm the formation of heterojunctions and to affirm their potential in imparting efficient charge separation at the interface. The prepared heterojunctions were shown to improve the photocatalytic ability of aged CF nanocrystals by improving crystallinity and retarding phase transformations. The CF/SnS heterojunction sample prepared by mixing in the ratio of 5:1 has been shown to produce an impressive photocatalytic activity in the CO2 reduction to yield a CO yield of 153.1 μmol g–1 h–1 with high product selectivity. Morphological, crystalline, and optical characterizations have been performed to understand the photocatalytic mechanism of CO2 reduction using the CF/SnS heterojunction photocatalyst.