Enhanced Photocatalytic Property of γ-CsPbI₃ Perovskite Nanocrystals with WS₂

Abstract

Black perovskite-phase cesium lead tri-iodide (CsPbI3) has shown great potential in photochemical applications. However, colloidal CsPbI3 still suffers from the existence of ligands attached to the surface of nanocrystals (NCs) and serious photoluminescence (PL) quenching. Here, we develop two different γ-phase CsPbI3 (γ-CsPbI3) NCs/WS2 heterostructures with two different two-dimensional morphologies of WS2 (nanoplates and few-layered WS2 nanosheets) to improve the photocatalytic property of γ-CsPbI3 NCs. The large surface area and the presence of abundant functional groups on the surface of WS2 enable a bonding interaction with precursors in the mixture solution, which can reduce the number of ligands and promote the formation and crystal quality of γ-CsPbI3 NCs. Exhilaratingly, we find that γ-CsPbI3 NCs fabricated with few-layered WS2 nanosheets exhibit a significant enhancement in their photocatalytic property, which may result from the increased amount and improved crystal quality of γ-CsPbI3 NCs and the superior carrier-transport property of few-layered WS2 nanosheets, and these effects are beneficial for producing abundant hydroxyl radicals to completely degrade methylene blue (MB). The fresh γ-CsPbI3 NCs/few-layered WS2 nanosheets show a high photocatalytic degradation efficiency of nearly 100% in 30 min, and completely degrade MB into low-weight and low-toxicity inorganic molecules without any intermediate degradation products.