Au@Pd core–shell nanoparticles-decorated reduced graphene oxide: a highly sensitive and selective platform for electrochemical detection of hydrazine

Abstract

The tailored fabrication of noble metal-based bimetallic nanoparticles-decorated reduced graphene oxide (rGO) is highly demanding for its use as a clean and recyclable substrate for electrochemical performances. Herein, we have successfully prepared Au_core@Pd_shell with an average size of ∼11.5 nm on an rGO support (denoted as GAP) through a surfactant-free one-step synthetic protocol. The use of 2-propanol as a solvent as well as a reducing agent for the precursors demonstrates that the designed process is economically preferable for the scalable synthesis of the desired GAP material. Comparative electrocatalytic efficiency in terms of hydrazine (N₂H₄) oxidation reveals the optimized noble-metal loading on rGO nanosheets and also the composition to capitalize maximum advantage from the as-synthesized GAP material. The most effective electrocatalyst, GAP3 with optimized constituents, was then applied as a substrate to electrochemically determine N₂H₄ down to a trace concentration level with high selectivity and sensitivity. The limit of detection (LOD) from GAP3 is calculated to be 0.08 μM with a linear range of 2–40 μM from the chronoamperometric (CA) result at −0.15 V vs. SCE. The novelty of N₂H₄ detection by the designed substrate becomes evident while all of the related reports are reviewed. This electrochemical sensor was successfully applied further to detect trace-level N₂H₄ in various real water samples, indicating its promising practical application.