Real‐time Selective Detection of Hydrogen Peroxide Based on a Tantalum Deposited Pencil Lead Electrode for Evaluation of Enzyme Activities

In this study, we have carried out electrodeposition of tantalum (Ta) nanostructures on pencil lead electrode in non‐aqueous media at room temperature by applying a constant potential. The deposited Ta on pencil lead was examined for the catalytic effect regarding hydrogen peroxide (H 2 O 2 ) reduction with voltammetry and amperometry. Ta/pencil lead electrode exhibited amperometric sensitivity of 0.317 μA mM −1 cm −2 and fast response time of 0.75 s, where selective detection of H 2 O 2 was fulfilled without interruption from common electroactive biomaterials such as O 2 , uric acid, ascorbic acid, dopamine, acetamidophenol, and glucose. For practical applications, the dynamic concentration changes of H 2 O 2 during catalase and glucose oxidase‐involved reactions, either eliminating or producing H 2 O 2 , were successfully traced in real time with as‐prepared electrode. From the kinetics study for catalase and glucose oxidase, we evaluated Michaelis constants ( K m app ) as 7.8 mM for catalase and 37 mM for glucose oxidase, respectively.