Boosting photoelectrochemical detection accuracy of trace H2O2 by inducing holes accumulation on the MnOx/WO3

Restrained by sluggish migration dynamics of holes, the detection sensitivity and limit of an anodic photoelectrochemical (APEC) strategy for trace hydrogen peroxide (H₂O₂) is generally difficult to meet the demands of the current chemical industry. Herein, interface hole enrichment engineering is proposed to solve this challenge. Subsequently, manganese oxide species (MnO_x) was photo-deposited on tungsten trioxide (WO₃) as a proof-of-concept prototype photoanode. Photoelectric structure characterization demonstrated that MnO_x species were validated to diminish H₂O₂ oxidation overpotential by increasing the concentration and lifetime of photogenerated holes, accelerating significantly H₂O₂ oxidation. As a result, the MnO_x/WO₃ photoanode achieves a lower detection limit of 0.1 mM and a higher sensitivity of 4.81 μA cm⁻² mM⁻¹ for H₂O₂ detection respectively, which are 0.125 (0.8 mM) and 1.72 (2.79 μA cm⁻² mM⁻¹) times sensitive compared to that of WO₃ photoanode. This work demonstrates a hole enrichment strategy to boost the sensitivity of trace H₂O₂ analysis.