Fabrication of a highly selective nonenzymatic amperometric sensor for hydrogen peroxide based on nickel foam/cytochrome c modified electrode

The development of an accurate, rapid, and low-cost monitoring technique for hydrogen peroxide (H₂O₂) is an important issue in biology, medicine, and food industry to assess human health risks. Several electrochemical sensors for H₂O₂ detection have been reported. Although these sensors have demonstrated low detection limits with good stability and selectivity, most of them have complicated preparation processes. Therefore, a simple design is needed for controlled development of electrochemical sensor for detecting H₂O₂ in real samples with high flexibility and low capital cost. In this study, a simple H₂O₂ sensor was developed based on 3D porous nickel foam (Ni foam) electrode functionalized with cytochrome c (Cyt.c) as an electron transfer-mediating layer between active centers of the Ni foam (i.e., nickel hydroxide) and H₂O₂. Our findings revealed that the combination between Ni foam and Cyt.c could enhance the sensor performance in terms of sensitivity and selectivity, and allow the detection of H₂O₂ over a wide linear range with a detection limit of 2 × 10^-7 M and a sensitivity of 1.95 μA mM^-1. The Cyt.c/Ni foam sensor did not have potentially interfering components, such as ascorbic acid, uric acid, and dopamine; hence, is applicable for analyzing environmental samples, such as apple juice. This Cyt.c/Ni foam electrode enabled H₂O₂ sensing system responses with revisable, selective, and sensitive recognition of a wide range of H₂O₂ concentrations.