Preparation of Heterojunctions Based on Cs₃Bi₂Br₉ Nanocrystals and g-C₃N₄ Nanosheets for Photocatalytic Hydrogen Evolution

Heterojunctions based on metal halide perovskites (MHPs) are promising systems for the photocatalytic hydrogen evolution reaction (HER). In this work, we coupled Cs₃Bi₂Br₉ nanocrystals (NCs), obtained by wet ball milling synthesis, with g-C₃N₄ nanosheets (NSs), produced by thermal oxidation of bulk g-C₃N_4, in air. These methods are reproducible, inexpensive and easy to scale up. Heterojunctions with different loadings of Cs₃Bi₂Br₉ NCs were fully characterised and tested for the HER. A relevant improvement of H₂ production with respect to pristine carbon nitride was achieved at low NCs levels reaching values up to about 4600 µmol g^-1 h^-1. This work aims to provide insights into the synthesis of inexpensive and high-performing heterojunctions using MHP for photocatalytic applications.