Graphene Oxide-Wrapped Gold Nanorods for Direct Plasmon-Enhanced Electrocatalysis to Detect Hydrogen Peroxide and in the Hydrogen Evaluation Reaction

The modulation of electronic characteristics of a two-dimensional (2-D) graphene oxide (GO) nanosheet with plasmonic hot charge carrier doping is of great scientific prominence for improving and expanding its diverse applications in health and energy fields. Herein, we report a nanohybrid system of reduced GO-wrapped gold nanorods (GNRs) for plasmon acceleration under localized surface plasmon resonance (LSPR) excitation photoelectrochemical (PEC) biosensing of hydrogen peroxide (H₂O₂), followed by the early-stage detection of human cancer cells as well as hydrogen evolution reaction (HER) for energy production. A tremendously sensitive H₂O₂ biosensor device is constructed (GNRs@rGO/GC), which exhibits ∼4-fold enhanced electrocatalytic activity under 808 nm LSPR excitation (2 W/cm²), with a wide linear range from 5 μM to 10 mM, along with a lower limit of detection and sensitivity of 2.35 μM and 30.26 μA mM^–1 cm^–2, respectively. It is now proposed that the enhanced generation of hot charge carriers followed by their effective transportation and separation and an attentive electromagnetic field with a photothermal effect mainly contribute to the superior photoelectrocatalysis reaction, which is also directly related to the pH of a medium, light wavelength, and light intensity. The electrode device is finally applied for the PEC biosensing of cancer cells (HeLa) by measuring the current response of a released cancer biomarker (H₂O₂). Herein, we also report the plasmon-accelerated superior HER catalytic performance by the GNRs@rGO/GC device, where we found the decreased onset potential of 90 mV with an overpotential (η) of −0.386 V at 10 mV cm^–2 and a Tafel slope of ∼81 mV dec^–1 under LSPR excitation. This study reveals the plasmon-enhanced electrochemical performances of a plasmonic@2-D SC heterostructure nanohybrid material and henceforth makes it a potential candidate for electroanalysis, electrochemical energy conversion, electrochemical devices, and biomedical applications.