Insights into S-scheme charge transfer in α-Bi2O3/TiO2-NRA nanoheterostructures for enhanced photodegradation and biosensing applications

Abstract

Through a straightforward electrochemical deposition process, novel α-Bi₂O₃ (α-BO) nanoparticles (NPs) were successfully synthesized and deposited on highly ordered TiO₂ nanorod arrays (TONAs). Under UV-visible light irradiation, these nanohybrid materials exhibited enhanced photoelectrocatalytic (PEC) performance for the photodegradation of pollutants and biosensing applications. Notably, compared to the standalone TONAs and isolated α-BO, the α-BO/TONA (BT) nanocomposite showed a significant increase in PEC activity, primarily attributed to the efficient S-scheme charge transfer (CT) pathway facilitated by oxygen vacancy defects. Additionally, this study proposes a self-consistent interfacial S-scheme CT mechanism, mediated by the deposition amount of α-BO, evaluated through femtosecond transient absorption and time-resolved photoluminescence spectroscopy. Under UV-visible light irradiation, the optimal BT-20 composite achieved a photodegradation rate (η) of 98.5% for methyl orange, with enhancement factors of 1.63, 1.33, and 1.18 compared to BT-10, BT-15, and BT-40, respectively. Furthermore, PEC biosensing analysis of BT-20 was conducted for the detection of glutathione, yielding a limit of detection (LOD) of 0.3 μM and a linear range of 1 μM to 600 μM. Additionally, the LOD of BT-20 is 2.67, 2.33, and 1.67 fold smaller than that of BT-10, BT-15, and BT-40, respectively. This research helps us understand how to make better photocatalysts and develop new semiconductor devices for PEC biosensing.