Binder-free Ni–In₂O₃/Cu-foam heterostructured electrode for non-enzymatic H₂O₂ sensing

In this work, a binder-free, self-supported Ni–In₂O₃ heterostructured electrode was constructed on three-dimensional Cu foam for the non-enzymatic electrochemical detection of H₂O₂ under near-neutral conditions. In₂O₃ was conformally grown on Cu foam through a solvothermal process followed by calcination, and Ni species were then introduced by electrodeposition to form a Ni-containing/In₂O₃ composite coating with close interfacial contact and a hierarchically rough surface. Owing to its reduced charge-transfer resistance and enlarged electrochemically accessible surface, the Ni–In₂O₃/Cu foam electrode exhibited a sensitive amperometric response toward H₂O₂ reduction in 0.1 M PBS (pH 7.4) at −0.60 V vs. SCE. Two linear ranges were obtained, from 0.6 μM to 1.759 mM and from 2.059 to 9.059 mM, with corresponding sensitivities of 18.492 and 9.799 μA·mM −1 ·cm −2 , respectively, and a detection limit of 0.228 μM (S/N = 3). The sensor also exhibited good anti-interference performance, acceptable repeatability and reproducibility, and stable performance over 25 days. In standard-addition analyses of milk, tap water, and fetal bovine serum, recoveries ranged from 99.3% to 104.7%, with low RSD values (0.07%–3.25%), and Student's t -test revealed no significant difference between the measured and nominal concentrations ( p  > 0.05). Moreover, cytocompatibility evaluation and in situ monitoring of H₂O₂ released from PMA-stimulated cells demonstrated its potential applicability in cell-related redox analysis. These results demonstrate that the proposed Ni–In₂O₃/Cu foam electrode is a promising platform for sensitive, reliable, and practical H₂O₂ sensing under near-neutral conditions.