Modulation of Fermi level gap and internal electric field over Cs3Bi2Br9@VO-In2O3 S-scheme heterojunction for boosted charge separation and CO2 photoconversion
Modulating the internal electric field (IEF) represents a potential strategy to stimulate the photocatalytic activity of heterojunctions, especially S-scheme photocatalysts. Herein, a Cs 3 Bi 2 Br 9 @V O -In 2 O 3 (CBB@V O -In 2 O 3 ) S-scheme heterojunction, of which Cs 3 Bi 2 Br 9 perovskite quantum dots (PQDs) are embedded into mesoporous V O -In 2 O 3 hosts, is rationally designed as a cornerstone for further IEF manipulation. Briefly, by introducing oxygen vacancies (V O ) into the composed reduction semiconductor (mesoporous In 2 O 3 ), an enlarged Fermi level ( E F ) gap between CBB and V O -In 2 O 3 is achieved, yielding an intensified IEF over the CBB@V O -In 2 O 3 heterojunction. Such an enhanced IEF affords a much more robust driving force for directional carrier delivery, leading to accelerated carrier transfer of CBB@V O -In 2 O 3 heterojunction. Consequently, the optimized CBB@V O -In 2 O 3 heterojunction features desirable CO 2 -to-CO conversion efficiency, and its CO production rate reaches 130.96 μmol g −1 h −1 . The reaction intermediates and CO 2 photoconversion pathway were unraveled by in-situ diffuse reflectance infrared Fourier transform spectroscopy. Combining with the DFT calculation, it was revealed that oxygen vacancies in V O -In 2 O 3 act as reactive centers, which optimize the coordination modes of the intermediates, thus reducing the activation energy for photocatalytic CO 2 reduction. Our work demonstrates that the IEF modulation of S-scheme-based heterojunction could significantly boost the charge separation and then to drive efficient catalytic reaction , achieving high-efficiency solar fuel production.
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