Enhanced photoelectrochemical sensor based on ZnO–SnO2 composite nanotubes

• Composite nanotubes were used in photoelectrochemical (PEC) H2O2 sensor.
• It is the first time to use semiconductor composite as PEC biosensor.
• ZnO–SnO2 nanotubes electrode performs better PEC property than SnO2 nanotubes electrode.

Composite nanotubes modified electrodes with enhanced photoelectrochemical (PEC) performance have great potentialities in biological systems monitoring and detection. In this paper ZnO–SnO2 and SnO2 nanotubes were prepared by electrospinning. The results show that the visible light emission intensity of ZnO–SnO2 composite nanotubes is much higher than that of SnO2 nanotubes, indicating the existence of large amount of oxygen defects in ZnO–SnO2 nanotubes. Photocurrent response of SnO2 nanotubes electrode to hydrogen peroxide (H2O2) randomly increases with increased H2O2 concentration. While the dark current and photocurrent of ZnO–SnO2 nanotubes electrode decrease exponentially and linearly, respectively. Moreover, ZnO–SnO2 nanotubes electrode appears more outstanding H2O2 sensing capability than pure SnO2 nanotubes electrode under UV radiation. These can be well clarified by electron transfer mechanism in ZnO–SnO2 nano-composite. Different reactions on SnO2 and ZnO–SnO2 surface have been explained in details based on PEC performances of the two modified electrodes. This facile strategy extends the application of semiconductor composite for monitoring biomolecules with PEC method.