Journal Article

BiOCl Atomic Layers with Electrons Enriched Active Sites Exposed for Efficient Photocatalytic CO2 Overall Splitting

Nga, Ta Thi Thuy, Dong, Chung-Li, Wang, Yiduo, Peng, Ting, Guan, Qingqing, Zhang, Wenjie, Wang, Yiqing, Wu, Binglan, Shen, Shaohua

2025

Overview

Highlights BiOCl atomic layers (BOCNSs-i) were prepared by exfoliating hydrothermally synthesized BiOCl (BOCNSs) via ultrasonication in isopropanol for efficient photocatalytic CO 2 overall splitting to CO and O 2 . The obtained BOCNSs-i photocatalyst exhibits a distinctly improved photocatalytic performance to stoichiometrically produce CO and O 2 at the ratio of 2:1, with the CO evolution rate reaching 134.8 µmol g −1  h −1 under simulated solar light (1.7 suns) and reaching 13.3 mmol g −1  h −1 under concentrated solar irradiation (34 suns). With the thickness of BiOCl photocatalyst reducing to atomic layers, the charge carrier transfer and separation were enhanced by shortened transfer distance and the increased built-in electric field intensity, and electrons enriched Bi sites were exposed for activating CO 2 molecules. Given the limited exposure of active sites and the retarded separation of photogenerated charge carriers in those developed photocatalysts, photocatalytic CO 2 splitting into value-added chemicals has suffered from the poor activity and remained in great challenge for real application. Herein, hydrothermally synthesized BiOCl with layered structure (BOCNSs) was exfoliated into thickness reduced nanosheets (BOCNSs-w) and even atomic layers (BOCNSs-i) via ultrasonication in water and isopropanol, respectively. In comparison with the pristine BOCNSs, the exfoliated BiOCl, especially BOCNSs-i with atomically layered structure, exhibits much improved photocatalytic activity for CO 2 overall splitting to produce CO and O 2 at a stoichiometric ratio of 2:1, with CO evolution rate reaching 134.8 µmol g −1  h −1 under simulated solar light (1.7 suns). By surpassing the photocatalytic performances of the state-of-the-art Bi l O m X n (X: Cl, Br, I) based photocatalysts, the CO evolution rate is further increased by 99 times, reaching 13.3 mmol g −1  h −1 under concentrated solar irradiation (34 suns). This excellent photocatalytic performance achieved over BOCNSs-i should be benefited from the shortened transfer distance and the increased built-in electric field intensity, which accelerates the migration of photogenerated charge carriers to surface. Moreover, with oxygen vacancies (V O ) introduced into the atomic layers, BOCNSs-i is exposed with the electrons enriched Bi active sites that could transfer electrons to activate CO 2 molecules for highly efficient and selective CO production, by lowering the energy barrier of rate-determining step (RDS), *OH + *CO 2 −  → HCO 3 − . It is also realized that the H 2 O vapor supplied during photocatalytic reaction would exchange oxygen atoms with CO 2 , which could alter the reaction pathways and further reduce the energy barrier of RDS, contributing to the dramatically improved photocatalytic performance for CO 2 overall splitting to CO and O 2 .

• Publisher: Springer Nature Singapore,Springer Nature B.V,SpringerOpen
• Subject: BiOCl atomic layers / Carbon dioxide / Catalytic activity / Charge separation / CO2 overall splitting / Current carriers / Electric fields / Electrons / Energy / Engineering / Enrichment / Evolution / Exfoliation / Exposure / Irradiation / Isopropanol / Nanoscale Science and Technology / Nanotechnology / Nanotechnology and Microengineering / Oxygen atoms / Photocatalysis / Photocatalysts / Separation / Solar radiation / Splitting / Synthesis / Thickness