Controllable synthesis of highly active Au@Ni nanocatalyst supported on graphene oxide for electrochemical sensing of hydrazine

Bimetallic catalyst has attracted considerable attention due to the higher catalytic activity and better stability than monometallic. In this paper, different Au@Ni bimetallic structures decorated graphene oxide were prepared by adjusting the mass ratio of Au and Ni. A novel sensor based on Au@Ni bimetallic heterodimer (Au@Ni-BHD/rGO) or core-shell (Au@Ni-BCS/rGO) structure was constructed for hydrazine oxidation. The electrocatalytic activity was compared and verified by chronoamperometry, amperometry and cyclic voltammetry. Electrocatalytic active surface area was calculated by Randles-Sevick equation. The electrocatalytic performance of Au@Ni-BHD/rGO modified electrode was investigated and exhibited a low oxidation potential (0.07 V) with two wide linear range from 0.2 μM to 1 mM and 1 mM to 9 mM for sensing hydrazine with a low detection limit of 0.06 μM. Likewise, Au@Ni-BCS/rGO modified electrode towards the addition of hydrazine also showed a lower oxidation potential (0 V) with two wide linear range from 3 μM to 1 mM and 1 mM to 20 mM, and a low detection limit of 0.9 μM. Moreover, both of the modified electrodes offered high selectivity, good reproducibility and stability. This study demonstrates a promising sensing material for electrochemical detection of hydrazine and a new idea for the development of other sensors.