Three-dimensional nanoporous Au films as high-efficiency enzyme-free electrochemical sensors

Herein we develop an enzyme-free electrochemical sensor for hydrogen peroxide (H₂O₂) and hydrazine (N₂H₄) by preparing three-dimensional nanoporous gold (NPG) supported on three dimensional Ni foam. The NPG@Ni foam hybrid electrode was prepared via electrodeposition of an AuSn alloy film on a Ni foam substrate, followed by a chemical dealloying process to leach the Sn component. The morphology and structure of the as-prepared NPG@Ni foam hybrid were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectrum (EDS). The as-prepared hybrid electrodes showed high sensitivity and selectivity for the detection of both H₂O₂ and N₂H₄. The non-enzymatic sensor exhibits a linear response for H₂O₂ and N₂H₄ in the range of 20-9740 and 0.2-110.1 μM, with a sensitivity of 2.88 and 10.687 mA mM^-1 cm^-2, and a detection limit (S/N = 3) of 10 μM and 33 nM, respectively. The excellent sensitivity and selectivity make the NPG@Ni foam electrodes very attractive for electrochemical sensing applications.