Photocatalytic Hydrogen Evolution in Au Nanoparticles/Halide Perovskite Thin‐Film Heterostructures
Sougata Karmakar, Manoj Singh, Keya Haldar, Dipendu Sarkar, Srabanti Ghosh, Kiran Vankayala, Amarnath R. Allu, K. D. M. RaoABSTRACT
Photocatalytic hydrogen evolution using halide perovskite thin films is limited by intrinsic instability and limited charge separation efficiency at solid–liquid interfaces. Here, we report a hybrid Au nanoparticle/Cs 3 Bi 2 I 9 thin‐film heterostructure that enables efficient hydrogen generation under light illumination without the need for external bias. The Au nanoparticles (Au NPs) act as nucleation centers, promoting the growth of a vertically interconnected Cs 3 Bi 2 I 9 thin film, and simultaneously facilitate interfacial charge transfer across the metal–semiconductor junction. Under illumination (>1.8 eV), energetic carriers generated in Au transfer to Cs 3 Bi 2 I 9 through a built‐in electric field, while photogenerated carriers within Cs 3 Bi 2 I 9 are efficiently separated and transported to the reactive surface, increasing hydrogen evolution activity. The photocatalytic reactions occur at the Cs 3 Bi 2 I 9 /electrolyte interface, while the buried Au NPs remain protected from corrosion. Photocatalytic measurements in a chlorobenzene/HI/H 3 PO 2 medium show an approximately 384% increase relative to control samples. The Cs 3 Bi 2 I 9 overlayer further maintains the structural and functional stability of the heterostructure under reaction conditions. This work demonstrates a thin‐film approach based on interface engineering for achieving stable and efficient photocatalytic hydrogen evolution, while highlighting the importance of thin‐film architecture and metal–semiconductor interfaces in controlling charge transfer and durability.