**High Electrochemical Performance Phosphorus-Oxide Modified Graphene Electrode for Redox Supercapacitors Prepared by One-Step Electrochemical Exfoliation**

**Lei Zu 1, Xing Gao 1,2, Huiqin Lian 1, Xiaomin Cai 1,2, Ce Li 1,2, Ying Zhong 1, Yicheng Hao 1, Yifan Zhang 1, Zheng Gong 1, Yang Liu 1, Xiaodong Wang 2 and Xiuguo Cui 1,\***


Received: 18 May 2018; Accepted: 4 June 2018; Published: 9 June 2018

**Abstract:** Phosphorus oxide modified graphene was prepared by one-step electrochemical anodic exfoliation method and utilized as electrode in a redox supercapacitor that contained potassium iodide in electrolytes. The whole preparation process was completed in a few minutes and the yield was about 37.2%. The prepared sample has better electrocatalysis activity for I−/I<sup>−</sup>3 redox reaction than graphite due to the good charge transfer performance between phosphorus oxide and iodide ions. The maximum discharge specific capacitance is 1634.2 F/g when the current density is 3.5 mA/cm<sup>2</sup> and it can keep at 463 F/g after 500 charging–discharging cycles when the current density increased about three times.

**Keywords:** graphene; electrochemical anodic exfoliation; phosphorus oxide group; supercapacitors; iodide ions
