Non-enzymatic hydrogen peroxide detection using gold nanoclusters-modified phosphorus incorporated tetrahedral amorphous carbon electrodes

Sensitive electrochemical electrodes for hydrogen peroxide (H₂O₂) detection were developed using gold nanoclusters (NCs) to modify phosphorus incorporated tetrahedral amorphous carbon films (ta-C:P/Au). Au oxide covered Au NCs were electrodeposited on ta-C:P surfaces, and the size of Au/AuO_x NCs ranged between 50 nm and 91 nm, depending on the deposition time. The ta-C:P/Au electrodes exhibited higher electrocatalytic activity towards H₂O₂ oxidation compared to ta-C:P electrodes. This is due to the three-dimensional island structure of Au/AuO_x NCs, which accelerates electron exchange between ta-C:P and H₂O₂ in phosphate buffered solution. We also found that ta-C:P/Au electrodes with Au/AuO_x NCs of a smaller size and moderate coverage exhibited larger current response to H₂O₂ oxidation. The results obtained from amperometric response curves indicated that the use of Au/AuO_x NCs as microelectrodes directly favored H₂O₂ oxidation through hemispherical diffusion. The linear detection range of H₂O₂ at the non-enzymatic ta-C:P/Au electrodes was identified to be between 0.2 μM and 1 mM with a detection limit of 80 nM under optimized conditions. These ta-C:P/Au electrodes have potential applications in H₂O₂ sensing due to their high sensitivity, fast response and long-term stability.