Electrochemical reduction induced OVD in BiOBr nanosheets for sensitive photoelectrochemical detection of doxycycline

The regulation of semiconductor-electrolyte interface (SEI) is a promising way to optimize the photoelectrochemical performance of the semiconductor. Herein BiOBr nanosheets were electrochemically reduced to form oxygen vacancy defects (OVD) on the surface, thus increasing the carrier concentration and narrowing the space charge region at SEI. The best photoelectric response was obtained when the reduction potential was −0.2 V vs. Ag/AgCl. The OVD modified BiOBr structure was confirmed by different techniques. The electrochemical impedance spectroscopy (EIS) and Mott-Schottky (MS) plots evidenced the carrier concentration increase and the internal electric field enhancement. The time resolved photoluminescence (TRPL) measurements reflected the life time of photogenerated carriers was prolonged obviously. The optimized sample was chose for photoelectrochemical (PEC) detection of doxycycline (DOC). The fabricated PEC sensor could sensitively distinguish DOC solutions with concentrations varying from 0.1 μM to 100 μM. The photocurrent exhibited a linear relationship against the logarithm of concentration. The sensitivity was 8.21nA per logarithm and the limit of detection (LOD) was 0.026 μM at 3σ/S. The PEC sensor also displayed good anti-interference capacity and excellent stability. Our work shed light on the control of PEC performance of BiOX (X = Cl, Br, I) through introducing electrochemically induced OVD.