Enhanced Photocatalytic Performance Via the Synergistic Effects of Oxygen Vacancies and S-Scheme Heterojunctions in Bi12o17cl2/Bi2s3

Abstract

The creation of S-scheme heterojunctions coupled with oxygen vacancies (OVs) engineering has emerged as a highly effective approach to augmenting photocatalytic activity. In this pioneering study, we have successfully fabricated Bi12O17Cl2/Bi2S3 S-scheme heterojunction photocatalysts (ROV-BOC/BS) by ingeniously growing Bi2S3 (BS) nanorod onto the surface of OVs-enriched Bi12O17Cl2 (ROV-BOC) nanosheet via an innovative anion exchange method. Spectroscopic analyses using XPS and ESR reveal a marked increase in the concentration of OVs within the ROV-BOC/BS composite following the integration of ROV-BOC and BS. TEM and N2 adsorption-desorption measurements further substantiates the formation of a robustly interconnected heterojunction between these two components, significantly increasing the specific surface area and providing more active sites for photocatalytic reactions. Leveraging the synergistic effects of the heterojunction and enriched OVs, the light absorption capabilities and the efficiency of charge carrier separation and transport were significantly enhanced. Consequently, the fabricated ROV-BOC/BS composites demonstrated outstanding photocatalytic activity in the reduction of Cr(VI). Notably, the optimized ROV-BOC/BS-0.1 achieved a remarkable 95.52% Cr(VI) removal efficiency within 120 min, with apparent rate constants that were 5.39 and 23.86 times higher than those of pristine ROV-BOC and BS, respectively. Integrating insights from XPS, band structure analysis, free radical trapping experiments, and ESR characterizations, we propose that the combination of ROV-BOC and BS forms an S-scheme heterojunction. Within this heterojunction, electrons can be transferred from the OVs-induced defect level and the conduction band (CB) of ROV-BOC to the valence band (VB) of BS. This dual electron transfer path significantly improves the efficiency of charge separation. This investigation provides pivotal guidance for the advancement and design of novel S-scheme heterojunction photocatalysts featuring abundant oxygen vacancies, achieved via the ion exchange methodology.

Keywords: Photocatalytic, S-scheme heterojunction, Oxygen vacancies, Synergistical effect, In-situ construction