Graphene frameworks-confined synthesis of 2D-layered NiCoP for the electrochemical sensing of H2O2 at lower overpotential

A new 2D-layered nickel cobalt phosphide nanosheet confined by 3D graphene frameworks (denoted as NiCoP/GFs) is in situ controllably synthesized as a highly efficient and durable electrocatalyst, which is obtained from the transformation of corresponding NiCo layer double hydroxides and GFs. Hydrogen peroxide (H2O2) is selected as a demonstration to study the electrochemical sensing performance of the NiCoP/GFs. Benefiting from 2D morphology of NiCoP and network structure of GFs, NiCoP/GFs exhibits remarkable electroactivity toward H2O2 at a relatively low overpotential of approximately − 0.3 V (vs sat. Ag/AgCl) in 0.01 M phosphate-buffered saline solution (PBS, pH = 7.4). The NiCoP/GFs-based H2O2 electrochemical sensor achieves a high sensitivity of ∼4398 μA mM−1 cm−2, a low detection limit of 0.028 ± 0.006 μM, and desirable selectivity. In addition, the sensor can sensitively detect H2O2 from living cancer cells. This study not merely broadens the synthesis methods of transition metal phosphide–based nanocrystals but the NiCoP/GFs also has broad prospects in diverse electrochemistry fields.Graphical abstractWe have reported a controllable synthesis of 2D nickel cobalt phosphide nanosheet confined by graphene frameworks (denoted as NiCoP/GFs) as a greatly efficient and durable electrocatalyst. The NiCoP/GFs exhibits remarkable electroactivity toward detection of H2O2 at a relatively low overpotential of approximately −0.3 V. Density functional theory (DFT) calculations further prove that regulation of the electronic structure of NiCoP by GFs lowers the adsorption free energy of *OOH intermediates, and thus contributes to the greatly improved the electrocatalytic performance of NiCoP/GFs toward H2O2 reduction. The developed NiCoP/GFs can be applied as excellent electrode materials for efficient electrochemical sensing of H2O2.