Dimethylammonium iodide stabilized bismuth halide perovskite photocatalyst for hydrogen evolution

Metal halide perovskites have emerged as novel and promising photocatalysts for hydrogen generation. Currently, their stability in water is a vital and urgent research question. In this paper a novel approach to stabilize a bismuth halide perovskite [(CH₃)₂NH₂]₃[BiI₆] (DA₃BiI₆) in water using dimethylammonium iodide (DAI) without the assistance of acids or coatings is reported. The DA₃BiI₆ powder exhibits good stability in DAI solutions for at least two weeks. The concentration of DAI is found as a critical parameter, where the I- ions play the key role in the stabilization. The stability of DA3BiI6 in water is realized via a surface dissolution–recrystallization process. Stabilized DA₃BiI₆ demonstrates constant photocatalytic properties for visible light-induced photo-oxidation of I^- ions and with PtCl4 as a co-catalyst (Pt-DA₃BiI₆), photocatalytic H2 evolution with a rate of 5.7 μmol⋅h^-1 from HI in DAI solution, obtaining an apparent quantum efficiency of 0.83% at 535 nm. This study provides new insights on the stabilization of metal halide perovskites for photocatalysis in aqueous solution. [Figure not available: see fulltext.]