Towards an Improved Electrocatalytic Material for Detection of Polyphenols Based on Transition Metal Phosphides Anchored on Reduced Graphene Oxide

Abstract

The design of advanced materials with catalytic activity for detection of a target molecule is key to construct a sensitive electrochemical sensor. Transition metal phosphides (TMPs) have recently attracted substantial interest and are widely investigated as electrode material in the field of energy conversion/storage. TMPs have also been exploited for electrochemical sensing showing promising results for molecular detection. In this work, we report the preparation of a composite consisting of bimetallic cobalt−nickel phosphide (CoNiP) nanoparticles supported on reduced graphene oxide (rGO) and study the impact of phosphorization and presence of rGO on the electrochemical response using hydroquinone (HQ) as a model phenolic compound. The results show that the catalytic performance of CoNiP@rGO is a consequence of the synergetic interaction between different atoms of CoNiP and rGO, where P increases the proton concentration at the electrode interface favoring a catalytic mechanism where metal centers are oxidized. In the presence of rGO this effect is suppressed due to the formation of high valence states of CoNiP. The remarkable electrocatalytic performance may originate from the modulation of the electronic structure together with the large electroactive surface area and low electron-transfer resistance, enabling CoNiP@rGO to be a promising candidate for electrochemical sensor construction. Electrode materials containing bimetallic transition metals (Co and Ni) are investigated. The role of rGO and P in the electrochemical properties of the materials is revealed. Co and Ni participate in the HQ oxidation by a catalytic process in the absence of rGO. The presence of P increases the rate of the chemical reaction. rGO favors the rate of charge transfer and suppress the catalytic effect in a large extent.