A photoelectrochemical sensor for highly sensitive detection of H2O2 based on [Fcmim][N(CN)2]@Nafion® film modified GaN through a parallel catalysis strategy

Abstract

A photoelectrochemical (PEC) sensing system for H2O2 detection had been proposed based on parallel catalytic method in the presence of a ferrocene derivative. 3,3-bis(1-ferrocene methyleneimidazole-3-) boron dihydrodicyanamide ([Fcmim][N(CN)2]) was synthesized and immobilized on the surface of a GaN photoanode by the Nafion® film. A circulating H2O2-O2-H2O2 system was constructed using [Fcmim][N(CN)2] as bifunctional catalyst. In the cyclic process, H2O2 is catalyzed by [Fcmim][N(CN)2] to produce O2, which is then reduced to H2O2 by photogenerated electrons of GaN. The reduction process of O2 is also catalyzed by the same ferrocene catalyst. The regenerated H2O2 continues to be decomposed, causing O2 and H2O2 to fall into a photoelectrochemical cycle of H2O2-O2-H2O2. The decrease of the photocurrent by O2 was markedly amplified because the H2O2 and O2 were periodically regenerated. On the other hand, the diffusion rate of dissolved O2 through the Nafion® film is lower than the photoelectrochemical reduction rate of O2 on the GaN photoanode, thus the interference of dissolved O2 in the solvent could be eliminated during repeated on/off cycles of illumination. In the range of 4.00 nM - 0.720 μM and the limit of detection was 1.23 nM (3 S/N), PEC signal is linearly correlated with the logarithm of H2O2 concentration under optimized conditions. This method has a wide application prospect in environmental analysis and food safety analysis. For example, bilirubin can be detected using Nafion® in combination with bilirubin oxidase and [Fcmim][N(CN)2].