Sensitive photoelectrochemical determination of low concentrations of chlortetracycline by combining <i>in situ</i> electrochemically reduced BiOBr with SPR active AuNPs

Abstract The concentrations of tetracyclines can be conveniently measured by photoelectrochemical (PEC) technique using semiconductor electrodes. However, the sensitivity of the detection is greatly restricted by the photoelectric response. Herein, Au nanoparticles (AuNPs) were dispersed on the surface of in situ electrochemically reduced BiOBr (ERBOB) electrode so as to generate more photoinduced electrons and synergistically enhance the charge separation through electrochemical reduction induced oxygen vacancy defects (OVD). In contrast with pure BiOBr sample, the FTO/ERBOB/AuNPs photoelectrode displays wider visible light absorption range and higher photoinduced carrier separation efficiency, resulting in the remarkable enhancement of the photoelectric response. A plausible mechanism suggests that the strong interaction between the positively charged OVD layer in ERBOB and the adjacent SPR active Au nanoparticle layer play a key role in the amplification of the photoelectric signal. Additionally, the photoelectrode exhibits a highly sensitive signal-off type detection performance when used to determine low value concentrations of chlortetracycline. The sensitivity is 53.9 nA per decade of concentration and the detection limit of 0.073 μM at 3 σ /S. It is believed that the designed layered structure and the facile fabrication procedure will shed some lights on the design and preparation of high performance metal oxide-SPR NPs related photoelectrodes.