Preparation of Heterojunctions Based on Cs 3 Bi 2 Br 9 Nanocrystals and g-C 3 N 4 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 Cs 3 Bi 2 Br 9 nanocrystals (NCs), obtained by wet ball milling synthesis, with g-C 3 N 4 nanosheets (NSs), produced by thermal oxidation of bulk g-C 3 N 4, in air. These methods are reproducible, inexpensive and easy to scale up. Heterojunctions with different loadings of Cs 3 Bi 2 Br 9 NCs were fully characterised and tested for the HER. A relevant improvement of H 2 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.