Fluorine-doped carbon: A metal-free electrocatalyst for oxygen reduction to peroxide

Abstract

Electrochemical synthesis in-situ of hydrogen peroxide (H2O2) is an alternative to the anthraquinone oxidation (AO) process. The catalyst with high performance and excellent stability is the key part of oxygen reduction reaction (ORR). Fluorine (F) has high electronegativity, which can induce the polarization of adjacent carbon, produce active centers and increase the force between oxygen and carbon. In this work, we used a simple synthesis method to prepare F-doped carbon electrocatalyst in F2 atmosphere. The F-doped carbon as cathode was used to generate H2O2 via the two-electron pathway. The H2O2 concentration and selectivity of catalyst can reach 2837.5 mg L−1 and 95.7% after electrolyzing three hours, respectively. The linear sweep voltammetry shows that the onset potential of F-doped carbon is 37 mV more positive than that of pristine carbon, and its limited current density of catalyst reach 5.882 mA cm−2. The density functional theory (DFT) calculation demonstrates the covalent bonds CF2 can activate O2 and promote desorption of intermediate OOH to enhance H2O2 production. The prepared F-doped carbon with excellent performance and outstanding cycle durability is a promising electrocatalyst.