Hierarchically porous carbon nanofibers embedded with cobalt nanoparticles for efficient H₂O₂ detection on multiple sensor platforms

Hydrogen peroxide (H₂O₂) detection is essential in many industrial and biological processes. Current applications of H₂O₂ electrochemical sensors are often limited by the high cost of precious metal electrocatalysts and sophisticated instrumentation requirements. Here, we demonstrate a highly active non-precious metal cobalt/carbon nanocomposite electrocatalyst for efficient H₂O₂ sensing on multiple sensor platforms, including conventional glassy carbon electrodes (GCEs), free-standing film electrodes, and screen-printed electrodes (SPEs). This nanocomposite was synthesized by carbonation of electrospun polyacrylonitrile nanofibers containing zeolitic imidazole framework (i.e., ZIF-67) particles. The resulting hierarchically porous nitrogen-doped carbon nanofiber film contains hollow mesoporous carbon particles and exposed cobalt nanoparticles, which has sufficient mechanical strength as a self-standing film and is also electrically highly conductive. Consequently, when tested using GCEs, it exhibits an ultrahigh sensitivity of 300 μA/cm² mM and a detection limit of 10 μM below the permissible H₂O₂ residual limit in food packaging permittable by the US FDA. When utilized as free-standing film electrodes, its linear detection range extends an order higher to 50 mM. It is also highly specific toward H₂O₂ sensing without responses to multiple interfering analytes. Further, it enables mobile H₂O₂ detection on SPEs when integrated with a portable potentiostat and mobile phone. This new nanocomposite electrocatalyst can open various new opportunities for practical H₂O₂ sensing applications.