Electron confinement promoted the electric double layer effect of BiOI/β-Bi2O3 in photocatalytic water splitting

• Published in: Journal of colloid and interface science 2024-01, Vol.653 (Pt A), p.94-107
• Main Authors: Shan, Lianwei, Fang, Zilan, Ding, Guodao, Shi, Ziqi, Dong, Limin, Li, Dan, Wu, Haitao, Li, Xuejiao, Suriyaprakash, Jagadeesh, Zhou, Yangtao, Xiao, Yanwei
• Format: Article
• Language: English
• Subjects: Confinement; domain; Electric double layer; electrophoresis; Gibbs free energy; hydrogen production; liquids; molecular dynamics; Photocatalysis; photocatalysts; S-scheme heterojunction; solvents
• ISSN: 0021-9797; 1095-7103; 1095-7103
• DOI: 10.1016/j.jcis.2023.09.059

[Display omitted] •BiOI/β-Bi2O3 obtains excellent photocatalytic hydrogen evolution ability.•We unveil the transition dipole moment in BiOI/β-Bi2O3 heterojunction.•Photogenerated electrons are confined in β-Bi2O3 component of BiOI/β-Bi2O3.•BiOI/β-Bi2O3 can provide proper ΔGH* in hydrogen evolution process.•BiOI/β-Bi2O3/H2O interface can lead to a proper electric double layer structure. In the realm of photocatalysis, understanding the interface issues (solid/solid and solid/liquid) inherent in heterojunction at the atomic level is the ultimate for engineering an efficient photocatalyst. Herein, an electrophoretic deposition technique is adopted to synthesize BiOI/β-Bi2O3 heterojunction, exhibiting superior photocatalytic activity and stability in H2 evolution (91.5 μmol g–1 h−1) and H2O2 production (11.3 mg L–1 h−1). Combined with the experimental and computational results, a lower free energy of hydrogen evolution reaction (252.4 meV) has been observed contrast to BiOI and β-Bi2O3 samples. A carrier transfer process of like S-scheme heterojunction is proposed based on density of states (DOS) and carrier distribution calculations. The theoretical calculations illustrate the transition dipole moment, migration and accumulation of carrier in BiOI/β-Bi2O3 heterojunction. Subsequent ab initio molecular dynamics (AIMD) results of solid/liquid interface systems (BiOI/β-Bi2O3/H2O and β-Bi2O3/H2O) unravel the interface H2O (solvent) behaviors. The local aggregation of photo-generated electrons in BiOI/β-Bi2O3/H2O leads to a large potential drop, high proton migration rate and the steady electric double layer (EDL) structure compared to the β-Bi2O3/H2O, which facilitates the occurrence of photocatalytic reactions in solution. In addition to offering new insights into the hydrogen evolution and proton transfer in the EDL model and the association between the heterojunction effect and EDL structure, this work also introduces a novel design strategy for Bi-based heterojunctions.