Strain‐Engineering of Mesoporous Cs₃Bi₂Br₉/BiVO₄ S‐Scheme Heterojunction for Efficient CO₂ Photoreduction

Abstract

Slow charge kinetics and unfavorable CO2 adsorption/activation strongly inhibit CO2 photoreduction. In this study, a strain‐engineered Cs3Bi2Br9/hierarchically porous BiVO4 (s‐CBB/HP‐BVO) heterojunction with improved charge separation and tailored CO2 adsorption/activation capability is developed. Density functional theory calculations suggest that the presence of tensile strain in Cs3Bi2Br9 can significantly downshift the p‐band center of the active Bi atoms, which enhances the adsorption/activation of inert CO2. Meanwhile, in situ irradiation X‐ray photoelectron spectroscopy and electron spin resonance confirm that efficient charge transfer occurs in s‐CBB/HP‐BVO following an S‐scheme with built‐in electric field acceleration. Therefore, the well‐designed s‐CBB/HP‐BVO heterojunction exhibits a boosted photocatalytic activity, with a total electron consumption rate of 70.63 µmol g−1 h−1, and 79.66% selectivity of CO production. Additionally, in situ diffuse reflectance infrared Fourier transform spectroscopy reveals that CO2 photoreduction undergoes a formaldehyde‐mediated reaction process. This work provides insight into strain engineering to improve the photocatalytic performance of halide perovskite.

Perovskite Paradigm Shift: A Green Revolution with Lead-Free Alternatives in Photocatalytic CO2 Reduction

“…(g, i) HR-TEM images and (h, j) the corresponding strain maps along ε xy determined by GPA of pure CBB and s-CBB/HP-BVO. Reproduced with permission from ref . Copyright 2023, Wiley-VCH.…”

“…For instance, the combination of Schottky and Z-scheme heterojunction formation could supply rich catalytic active site and SPR effect while governing charge separation and high redox potentials as demonstrated by Au-Cs 3 Bi 2 Br 9 /V 2 O 5 . Other reported examples applied in CO 2 photoreduction are the coupling of encapsulation and Z-scheme construction (Cs 2 CuBr 4 @CeO 2 , Cs 3 Bi 2 Br 9 @TiO 2 , Cs 2 AgBiBr 6 @TiO 2 , and Cs 3 Bi 2 Br 9 @α-Fe 2 O 3 ), Z-scheme heterojunction and strain engineering (strained Cs 3 Bi 2 Br 9 /BiVO 4 ), and Z-scheme and vacancy engineering (H 2 WO 4 /Cs 2 AgBiBr 6 with Br vacancies), harnessing the advantages from each strategy.…”

“…The surface-bound intermediate species during CO 2 photoconversion has also been studied experimentally using in situ DRIFTS as depicted in Figure b,c . Another LFHP-based photocatalyst was proposed to form intermediates such as CHO and CH 3 O prior to yielding CH 4 via dehydration and proton-coupled electron transfer as deduced from in situ DRIFTS (Figure d,e) . However, this pathway involved double and triple proton-coupled electron transfer for the formation of CHO and CH 3 O, respectively, suggesting that the formation of these intermediates may be more challenging due to higher energy requirements and complexity from steric hindrance and increased coordination.…”

“…The red line denotes the proposed pathway, while the gray line represents the eliminated pathway. Reproduced with permission from ref . Copyright 2023, Wiley-VCH.…”

Enhancing CO2 photoreduction through unique 2D MOF-based heterostructures with metalloid doping

“…1–4 In the CO 2 photoreduction process, photocatalysts absorb solar energy, leading to the generation of photogenerated electrons for reduction and holes that oxidize water molecules, resulting in the production of O 2 and H + . 5–7 Simultaneously, this process reduces CO 2 to carbon-containing compounds such as CO and CH 4 . The intrinsic properties of a photocatalyst play a critical role in enhancing the efficiency of solar light-driven photocatalytic CO 2 reduction.…”