Black phosphorus/Bi19Br3S27 van der Waals heterojunctions ensure the supply of activated hydrogen for effective CO2 photoreduction

• Published in: Applied catalysis. B, Environmental Environmental, 2022-11, Vol.317, p.121727, Article 121727
• Main Authors: Niu, Ranran, Liu, Qiaoyun, Huang, Baojing, Liu, Zhongyi, Zhang, Wenfen, Peng, Zhikun, Wang, Zhiyuan, Yang, Yongpeng, Gu, Zhenkun, Li, Jun
• Format: Article
• Language: English
• Subjects: Activated hydrogen; Black phosphorus/Bi19Br3S27 composite; CO2 photoreduction; Photocatalysis; Van der Waals heterojunction
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.121727

Photocatalytic CO2 reduction (PCC) into solar fuels has been identified as a green avenue for carbon emission reduction. The reactions are usually restricted by the competitive hydrogen production reactions so that the acquisition and utilization of activated hydrogen (H*) in photocatalytic CO2 reduction are hard to guarantee. Herein, heterojunction engineering, regarding amendatory H* supply and balancing hydrogen production reactions simultaneously, for enhancing PCC is achieved by fabricating black phosphorus (BP) nanosheets supported on Bi19Br3S27 nanorods (BP/BBS). Density functional theory calculations united with experimental researches confirm the charge transfer conforms to S-scheme mechanism, which guarantee the efficient separation of photogenerated carriers to facilitate CO2 photoreduction. Free energy analysis reveals the formation of BP/BBS heterojunction changes the active sites from BBS to BP, which decrease the rate-limiting H* formation step from 1.94 (on BBS) to 1.13 eV (BP/BBS heterojunction), ensuring the supply of activated H* for PCC. We found that the heat of the PCC is conducive to dominant protonation of CO2 not H* desorption, which can greatly improve the reduction efficiency of CO2. As a result, the optimized BP/BBS heterojunction achieves an enhanced generation rate of solar fuels in liquid or gas-solid phase system with CO generation rate of 395.7 and 35.4 μmol g−1catalyst, respectively. This work provides an efficient strategy to achieve the supply of activated H* for PCC and other photochemical process. [Display omitted] •The S-scheme BP/Bi19Br3S27 heterojunction were fabricated for UV–vis–NIR light-driven photocatalytic CO2 reduction.•Van der Waals heterojunction accelerated the separation and migration of photogenerated carriers.•The Van der Waals heterojunction revealed enhanced photocatalytic activity for CO2 reduction.•The formation of BP/BBS heterojunction decreases the rate-limiting H* formation step, ensuring the supply of activated H*.•The photocatalytic mechanism was unveiled based on the experiments and DFT calculations.