Fluorine doping-induced oxygen vacancy-rich TiO₂ via contact activation for signal boosting in electrochemical sensing

TiO₂, as an important member of transition metal oxides, exhibits great potential for the fabrication of sensors while the semi-conductive property of pure TiO₂ makes the superior sensitivity and current response difficult to achieve in electroanalysis. Herein, an effective strategy is firstly proposed to realize F doping of TiO₂ through a simple room-temperature contact activation. Through the investigation of characterization and electrochemical measurement, we verified the successful F doping and introduction of oxygen vacancies (OVs) into TiO₂ and the resulting positive effect on electrochemical sensing performance. Then we fabricated an electrochemical sensor based on F-doped O_V-TiO₂ and evaluated its potential to be applied for the detection of dopamine hydrochloride (DAH). Benefiting from the adjustment of surface chemical state and microstructure of TiO₂, the electrochemical sensor based on F-doped O_V-TiO₂ showed an approximate 350-fold increased amperometric response towards DAH and exhibited a high sensitivity of 630 μA mM⁻¹ cm⁻², a wide linear range of 2–682.7 μM, a low detection limit of 0.13 μM as well as satisfying reproducibility and stability, which could be used in the detection of DAH in animal feed with high recovery rate. This work proved that the doping of fluorine and the corresponding introduction of oxygen vacancies can be well utilized to adjust the electrical conductivity and catalytic activity of TiO₂, which effectively advanced its reliability to be applied in electrochemical sensing and provided an innovative strategy to broaden the application of semiconductors in efficient electrochemical detection.