Oxygen vacancy-rich Bi2WO6 nanocrystals for fast and wide-range photoelectrochemical sensing of hydrogen peroxide

Improper treatment of highly active natural or edible water will cause environmental pollution, and hydrogen peroxide (H2O2) is a common pollutant. Wide-range concentrations and short half-lift time of H2O2 in different sample conditions make it a challenge for its accurate and fast detection. We present here the use of Bi2WO6 nanocrystal with rich oxygen vacancy (Bi2WO6-V) to construct a photoelectrochemical (PEC) sensor for fast and wide-range qualification of H2O2. Under visible light irradiation, the H2O2 detection limit of the Bi2WO6-V PEC sensor reaches 0.5 μM, which is 10 times that without light. The mechanism of PEC sensing performance toward H2O2 was studied by UV–vis, Mott-Schottky characterization and PEC measurements, finding that the driving force of photogenerated electrons (−0.627 V) caused by energy level difference between Bi2WO6-V and the reduction of H2O2 ensures that the visible light can be effectively absorbed to reduce H2O2 to H2O. The calibration curve of H2O2 obtained by the proposed PEC sensor regions from 1.5 μ M to 230 mM, with high response time and good selectivity. In addition, the sensor can detect H2O2 in actual samples-milk and lake water, which has broad prospects in environmental monitoring.