Optimizing the rate capability of Nickel Cobalt Phosphide nanowires into graphene oxide by the outer/inter-components synergy effect

Abstract

The bimetallic phosphides have been identified as promising alternative electrode materials owing to the admirable conductivity and electrochemical activity. Nevertheless, severe agglomeration of single-component bimetallic phosphides hinders its extensive application. Moreover, the current research lack of in-depth research for the effect of outer/inter-components synergy on the rate capability. In this work, novel nickel cobalt phosphide nanowires into two-dimensional graphene oxide nanosheets (GO@NiCoP) is design and prepared by combining the hydrothermal process and phosphorization. The GO serves as the conductive path to improve the composite conductivity, and provides the abundant oxygen-containing function group to coordinate with the metal cations of NiCoP, thereby can boost the overall structural stability. The NiCoP possess optimal intercomponent synergy effect such as optimal -OH- adsorption energy and deprotonation energy, leading to the enhanced potential on electrochemical reaction. Taking advantages of these materials, the GO@NiCoP electrode displays a high specific capacitance of 1125 F g-1 (155 mAh g-1) at 2 A g-1 and a high cycling stability of 104.88% capacitance retention after 5000 cycles at 30 A g-1. Interestingly, the GO@NiCoP electrode delivers an exceptional rate capability of 84.09% capacitance retention at 20 A g-1 and 39.77% capacitance retention at 60 A g-1 owing to its stable structure and excellent conductivity. In addition, we fabricated GO@NiCoP//AG ASC device which delivers a desirable energy density of 27.71 Wh kg-1 at 788 W kg-1. To widen the application, a self-charging power system with satisfactory lighting time was constructed by the ASC device. In short, the outstanding electrochemical performance of the electrode materials provides a novel perspective for enhancing the rate capacity of electrode materials by the outer/inter-components synergy effect.