Water‐Stable DMASnBr₃ Lead‐Free Perovskite for Effective Solar‐Driven Photocatalysis

Abstract

Water‐stable metal halide perovskites could foster tremendous progresses in several research fields where their superior optical properties can make differences. In this work we report clear evidence of water stability in a lead‐free metal halide perovskite, namely DMASnBr3, obtained by means of diffraction, optical and X‐ray photoelectron spectroscopy. Such unprecedented water‐stability has been applied to promote photocatalysis in aqueous medium, in particular by devising a novel composite material by coupling DMASnBr3 to g‐C3N4, taking advantage from the combination of their optimal photophysical properties. The prepared composites provide an impressive hydrogen evolution rate >1700 μmol g−1 h−1 generated by the synergistic activity of the two composite costituents. DFT calculations provide insight into this enhancement deriving it from the favorable alignment of interfacial energy levels of DMASnBr3 and g‐C3N4. The demonstration of an efficient photocatalytic activity for a composite based on lead‐free metal halide perovskite in water paves the way to a new class of light‐driven catalysts working in aqueous environments.

Water-driven boost in the visible light photocatalytic performance of Cs2AgBiBr6 double perovskite nanocrystals

“…[17][18][19] Although a variety of lead-free halide perovskites have been reported over the past several years, there are a few reports about lead-free perovskites in the photocatalytic eld due to their instability and discrepancy between their structures and photocatalytic performance. 20,21 Lead-free double halide perovskites with a formula of Cs 2 AgBiBr 6 possesses improved stability, signifying a promising photocatalytic material. [22][23][24][25][26][27][28][29] In 2018, Zhou and his co-workers employed Cs 2 AgBiBr 6 quantum dots to reduce CO 2 .…”

Air- and water-stable and photocatalytically active germanium-based 2D perovskites by organic spacer engineering

“…blue versus black patterns in Figure 2A). 9,21 In the rescaled inset of Figure 2A, we highlighted the peaks around 10 -40 to put in prominence the very good agreement between the patterns in the whole diffraction range.…”

“…24 Similar water stability has been also observed in some Sn-based MHPs, namely DMASnBr 3 and PEA 2 SnBr 4 . 8,9 In the first material, the mechanism leading to improved stability and effective photocatalytic activity results from the valence band energy stabilization, which should reduce the exposure of the material to oxidants, restoring a value similar to MAPbI 3 , healing the material from degradation into Sn 4+ phases and self-p-doping effects. 30,31 On the other hand, the improved stability in PEA 2 SnBr 4 was again related to the nature of surface-terminating groups and the presence of hydrophobic PEA moiety.…”

“…Hydrogen photogeneration characteristics have been determined according to a commonly employed protocol we already applied for other MHPs. 8,9,21 First, we determined the hydrogen evolution rate (HER) of pure PhBz 2 GeBr 4 under simulated solar light, which turned out to be $6 mmol g À1 h À1 , a low but relevant value for a pure MHPs, also considering the relatively high band gap of the materials, 3.6 eV, which corresponds to efficient ll OPEN ACCESS absorption only in the UV region of the light spectrum (in line with the UV-vis absorption spectrum; Figure 1C). To enhance the photoactivity of the perovskite, we prepared composites with a well-known visible-light-absorbing semiconductor, namely g-C 3 N 4 .…”

“…Metal halide perovskites (MHPs) are attracting huge interest for their possible application in heterogeneous photocatalysis following the recent synthesis of materials and heterostructures that have been found to be efficient for a plethora of photocatalyzed chemical reactions, including hydrogen generation and CO 2 reduction. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] A major limitation of MHPs in photocatalysis is their limited water stability, which derives from the high ionic character of the metal halide framework. 2,18,19 In this context, 2D-layered MHPs may be particularly suitable to overcome this issue in virtue of the vast range of organic spacers that can be inserted as a protective barrier between the inorganic perovskite layer(s).…”