Insights into the enhanced electrochemical sensing behavior of hydroquinone and catechol simultaneously enabled by ultrafine layer CoP-NiCoP heterostructure on graphene frameworks.

Abstract

Hydroquinone (HQ) and catechol (CC), two major dihydroxybenzene isomers, are toxic pollutants coexisting and impeding each other in the process of sample identification. Well-defined nanostructure and interface engineering enable the optimization of electrocatalysts for constructing highly efficient electrochemical sensors to realize detection of HQ and CC simultaneously. Herein, CoP-NiCoP heterojunction nanosheet with ultrafine layer-like morphology is designed and synthesized using graphene frameworks (GFs) as supporter via a solid-state phase transformation strategy (defined as CoP-NiCoP/GFs). Notably, the CoP-NiCoP/GFs displays enhanced electrocatalytic activity toward both HQ and CC compared with CoP/GFs, NiCoP/GFs, and GFs. Density functional theory calculations prove that the CoP-NiCoP structure is more favorable for the adsorption and desorption of both HQ and CC than those of CoP and NiCoP, thus could accelerate the HQ and CC electrocatalytic oxidation reaction on CoP-NiCoP/GFs electrode. A novel electrochemical sensing platform is developed based on CoP-NiCoP/GFs for detection of HQ and CC with wide linear detection ranges and low detection limits (0.256 μM for HQ and 0.379 μM for CC). Meanwhile, the proposed sensor could effectively determine HQ and CC in actual river water. This work demonstrates the great potential of NiCo-based metal phosphide in constructing an efficient dihydroxybenzene electrochemical sensor.