Oxygen vacancy-regulated TiO₂ nanotube photoelectrochemical sensor for highly sensitive and selective detection of tetracycline hydrochloride

Investigation of the mechanism of oxygen vacancy-regulated photoelectrochemical sensors for highly sensitive and selective determination of biomolecules containing electron-donating groups is an innovative research field. In this study, oxygen vacancy-regulated TiO₂ nanotube arrays (Ov-TNTs) with high photoelectrochemical activity were synthesized and applied to defect tetracycline hydrochloride (TC). The synergistic effect of oxygen vacancies and Ti³⁺ droves Ov-TNTs with a narrow energy band to generate more photogenerated carriers under irradiation. The photocurrent response of the oxygen vacancy-regulated photoelectrochemical sensor decreased with increasing TC concentration, which could be mainly attributed to adsorption of TC, which consumed part of the oxygen vacancies on the surface of Ov-TNTs. This system had excellent linearity in the range of 0.1–1000 nM with a detection limit of 0.33 nM (S/N = 3). In addition, the sensor was highly selective for TC determination due to the mutual electrostatic interaction between negatively charged TC-containing electron-donating groups (-NH₂ and -OH) and positively charged Ov-TNTs. This study provided a foundation for developing an oxygen vacancy-regulated adsorptive photoelectrochemical sensor.