Revealing the A‐Site Effect of Lead‐Free A₃Sb₂Br₉ Perovskite in Photocatalytic C(sp³)−H Bond Activation

Abstract

The lead‐free halide perovskite A3Sb2Br9 is utilized as a photocatalyst for the first time for C(sp3)−H bond activation. A3Sb2Br9 nanoparticles (A3Sb2Br9 NPs) with different ratios of Cs and CH3NH3 (MA) show different photocatalytic activities for toluene oxidation and the photocatalytic performance is enhanced when increasing the amount of Cs. The octahedron distortion caused by A‐site cations can change the electronic properties of X‐site ions and further affect the electron transfer from toluene molecules to Br sites. After the regulation of A‐site cations, the photocatalytic activity is higher with A3Sb2Br9 NPs than that with classic photocatalysts (TiO2, WO3, and CdS). The main active species involved in photocatalytic oxidation of toluene are photogenerated holes (h+) and superoxide anions (.O2−). The octahedron distortion by A‐site cations affecting photocatalytic activity remains unique and is also a step forward for understanding more about halide‐perovskite‐based photocatalysis. The relationship between octahedron distortion and photocatalysis can also guide the design of new photocatalytic systems involving other halide perovskites.

Constructing a Cs3Sb2Br9/g‐C3N4 Hybrid for Photocatalytic Aromatic C(sp3)H Bond Activation

“…To elucidate the catalytic mechanism, a series of control photocatalytic experiments were conducted in the absence of O 2 or with the addition of specific radical scavengers (Figure 4b and Table S2, Supporting Information). [ 37 ] First, the catalytic performance was dramatically reduced if O 2 was replaced with Ar, proving the necessity of O 2 for the catalytic reaction. [ 8 ] Second, no product could be detected in dark or without catalyst added.…”

“…Therefore, the possible photocatalytic reaction mechanism of Cs 3 Sb 2 Br 9 /g‐C 3 N 4 was proposed. [ 13,37 ] As shown in Scheme , under visible light irradiation, photoinduced electrons and holes were generated in the CB and VB of both Cs 3 Sb 2 Br 9 and g‐C 3 N 4 , respectively. Due to the difference of energy band position, fast charge transfer and separation occur with electrons accumulated in the CB of Cs 3 Sb 2 Br 9 and holes in the VB of g‐C 3 N 4 .…”

Rapid Acidic Media Growth of Cs3Bi2Br9 Halide Perovskite Platelets for Photocatalytic Toluene Oxidation

“…[31] Therefore, photoexcited holes play a crucial role in the activation of C(sp 3 )─H bonds at the methyl group of toluene, which is consistent with reported cases. [19,20]…”

“…[ 10 ] To date, several halide perovskite–based photocatalytic systems have been explored for various visible light–driven organic reactions, [ 11 ] such as aldehyde alkylation, [ 12 ] alcohol oxidation, [ 13 ] thiol coupling, [ 14 ] triose conversion, [ 15 ] CC, CO, and CN bond formation, [ 16 ] polymerization, [ 17 ] and dehydrogenation reactions. [ 18 ] Very recently, the challenging reaction of direct activation of C( sp 3 )H bonds under light irradiation was successfully realized over perovskite photocatalysts (e.g., supported Cs 3 Bi 2 Br 9 nanoparticles, [ 19 ] A 3 Sb 2 Br 9 nanomaterials, [ 20 ] and lead‐based NiO x /FAPbBr 3 /TiO 2 perovskite composites [ 21 ] ). However, the fast degradation of these active perovskite phases severely limits their practical and long‐term applications.…”

In Situ Construction of Lead‐Free Perovskite Direct Z‐Scheme Heterojunction Cs3Bi2I9/Bi2WO6 for Efficient Photocatalysis of CO2 Reduction

“…[ 21,22 ] Accordingly, multifarious lead‐free halide perovskites have been exploited and used as catalysts in the field of photocatalysis. [ 23–34 ] Among these lead‐free perovskites, bismuth‐based halide perovskites have received increasing attention owing to their low toxicity and high stability compared with LHPs. In particular, all‐inorganic cesium bismuth halide (Cs 3 Bi 2 X 9 , X = Br or I) perovskite nanocrystals have been actively exploited as photocatalysts for CO 2 reduction, [ 28 ] H 2 evolution, [ 32 ] organic synthesis, [ 25 ] and organic pollutant degradation.…”