Stable Lead-Free (CH₃NH₃)₃Bi₂I₉ Perovskite for Photocatalytic Hydrogen Generation

Abstract

Lead-halide perovskites have demonstrated promising performance in the field of photocatalytic hydrogen production. However, the toxicity of lead hinders their application. Herein, an environmentally friendly and lead-free perovskite (CH3NH3)3Bi2I9 was prepared by employing a simple and efficient hydrothermal route. It is found that (CH3NH3)3Bi2I9 exhibits excellent phase stability in hydriodic acid with different concentrations. Under visible light irradiation, it showed satisfactory cycle stability after 70 h of repeated H2 evolution without any degradation or oxidization. After using platinum as a cocatalyst, the photocatalytic rate for H2 evolution is about 169.21 μmol g–1 h–1, resulting in 14 times enhancement compared with the pristine one (about 12.19 μmol g–1 H–1 with 40 mg initial amount) and a solar-to-chemical conversion efficiency of 0.48%. Our research opens new possibilities for the application of lead-free perovskites in the field of photocatalysis.

Photosensitive Hybrid Nanostructured Materials: The Big Challenges for Sunlight Capture

“…Actually, they hold great potential to harness solar light efficiently due to their peculiar photoelectronic properties, including strong light absorption, low exciton binding, as well as long photo-excited charges lifetime and migration. Moreover, the composition of both inorganic (A, B, and O) and organic components can be adjusted to tune bandgap and optimize photocatalytic efficiency towards the desired reaction [308][309][310]. Particularly, Pb-based organohalide perovskites, such as methylammonium lead iodide (MAPbI 3 , MA = methylammonium), exhibit excellent photocatalytic properties due to marked light absorption, fast charge carrier migration properties, and poor recombination phenomena [309,311,312].…”

“…Moreover, the composition of both inorganic (A, B, and O) and organic components can be adjusted to tune bandgap and optimize photocatalytic efficiency towards the desired reaction [308][309][310]. Particularly, Pb-based organohalide perovskites, such as methylammonium lead iodide (MAPbI 3 , MA = methylammonium), exhibit excellent photocatalytic properties due to marked light absorption, fast charge carrier migration properties, and poor recombination phenomena [309,311,312]. These systems have been deeply investigated in the last years as light-absorbing layers in perovskite-based solar cells, an emerging photovoltaic technology, which rapidly achieved record efficiencies, and showed promising performances in the fields of hydrogen production and organic synthesis ( Figure 18) [312].…”

“…Table 7 reports a summary of the most promising hybrid perovskites and their photocatalytic features, as considered in this review. In order to address toxicity issues, environmentally-friendly lead-free perovskites have been designed [309,311,323]. Among those, bismuthate perovskite, (CH 3 NH 3 ) 3 Bi 2 I 9 , have been rising great interest due to excellent stability in reaction environment, as well as a marked photocatalytic activity under visible light towards H 2 production [309] and water contaminants degradation ( Figure 20) [323].…”

“…In order to address toxicity issues, environmentally-friendly lead-free perovskites have been designed [309,311,323]. Among those, bismuthate perovskite, (CH 3 NH 3 ) 3 Bi 2 I 9 , have been rising great interest due to excellent stability in reaction environment, as well as a marked photocatalytic activity under visible light towards H 2 production [309] and water contaminants degradation ( Figure 20) [323]. Finally, hybrid perovskites have been produced by different synthetic approaches and have shown outstanding photocatalytic performances, principally for H 2 production (in the range between 10-7000 µmol·h −1 ·g −1 ).…”

“…UV-Vis spectra (a) and schematic representation (b) of the MA 3 Bi 2 I 9 powder for H 2 evolution. Reprinted with permission from[309], Copyright (2019) American Chemical Society.…”