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 TiO 2 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 (-NH 2 and -OH) and positively charged Ov-TNTs. This study provided a foundation for developing an oxygen vacancy-regulated adsorptive photoelectrochemical sensor. • The introduction of oxygen vacancies drives TNTs with narrow energy band to generate more photogenerated carriers. • Oxygen vacancies can be used as electron traps for preferential adsorption of TC molecules with electron-donating groups. • The photoelectrochemical sensor exhibits superior sensitivity and selectivity for TC detection. • The mechanism investigation shows that the adsorption of TC on the surface of Ov-TNTs decreases the oxygen vacancies and Ti3 + concentration, resulting in the gradual recovery of photocurrent to pure TNTs. [ABSTRACT FROM AUTHOR]