Heterostructure-based 3D-CdS/TiO2 nanotubes/Ti: Photoelectrochemical performances and interface simulation investigation

Heterojunction can effectively improve the charge separation efficiency and facilitate electron transfer, producing a strong photoelectric signal. By using 3D-TiO2 nanotubes/Ti foil as support, CdS–TiO2 heterojunction electrodes with different CdS proportions were fabricated as photoelectrochemical (PEC) biosensor to respond the visible irradiation and improve the PEC performance of TiO2 nanotubes. Density functional theory (DFT) simulation was conducted to clarify the PEC process of CdS–TiO2NTs and revealed the important role of CdS in enhancing electron–hole separation on TiO2 nanotubes. Owing to the 3D tubular structure of the support, 2 mM CdS–TiO2 nanotubes/Ti PEC electrode exhibited low detection limit of 0.27 μM and good sensitivity of 328.87 μA mM−1 cm−2 for glucose in the range of 2–9 μM under visible illumination. The fabricated CdS–TiO2 nanotubes/Ti biosensor also showed high selectivity and good stability, which indicated a new candidate for biosensors.