Hofmann-Type Coordination Polymer-Derived Nickel Phosphide Nanoplates for Electrocatalytic Oxidation and Determination of Insulin

It is of key importance to design efficient insulin electrocatalysts based on nonprecious noble metal-free. However, the design of advanced nanostructured based metal phosphides is scarcely reported. In this work, for the first time, a novel insulin sensor based on Ni₂P electrode materials with nanoplate structure was designed. In this regard, Hofmann-type coordination polymers (HCPs) based on Ni(H₂O)₂[Ni(CN)₄]·H₂O (Ni–Ni HCP) were prepared and used as precursors to the preparation of Ni₂P. The unique layer structure of Ni–Ni HCP precursors can lead to the preparation of Ni₂P nanoplates with large surface areas, high availability of active catalytic centers, and abundant interior space for fast diffusion and boosted reaction kinetics. The electrochemical results showed that the Ni₂P nanoplates offer excellent capability toward insulin oxidation in 0.1 M NaOH electrolyte solution. Moreover, a proper linear relationship was obtained between insulin concentrations and the current responses in the range of 10 to 100 pM with the detection limit of 3 pM and with good capability for the determination of insulin in the human blood serum sample. This work offers a rational method for the structure engineering of Ni₂P nanoplates using HCP precursors, which can lead to the fabrication of high-performance insulin sensor.