A fuel-free self-powered sensor based on photoelectrochemical water/oxygen circulation for ultra-selective detection of levofloxacin

Although self-powered sensors (SPSs) have shown favorable application prospects as portable devices for on-site monitoring of pollutants, it remains challenging to address issues with fuel consumption in these devices as well as improve the detection selectivity. Herein, we constructed a fuel-free SPS for selective detection of levofloxacin (LEV) that was assembled with an In2S3/In2O3 photoanode and molecularly imprinted (MIP) functionalized cathode. Under illumination, the photogenerated holes oxidated water to oxygen at the photoanode, while the photogenerated electrons migrated to the cathode through the external circuit such that the oxygen was re-reduced to water at the cathode. Based on the resulting water/oxygen circulation between the two electrodes, the SPS had a maximum power density of 14.5 μW/cm2 without added fuel or sacrificial agents. Moreover, the molecularly imprinted polymer immobilized on the cathode allowed for specific recognition of LEV. Due to the steric hindrance effects of the MIP and the anti-interference performance from the cathode detection, the photocurrent significantly decreased with increasing LEV concentration. Under the optimum condition, the SPS responded linearly to LEV concentrations in the range of 0.1–107 nM with a detection limit of 0.047 nM and exhibited desirable stability, reproducibility, and selectivity. This work demonstrates a clean and green power generation method for portable sensors.