Electrocatalytic Reduction Behaviors Of Nitro-Compound On WC And Its Composite Electrode

Based on the review of application of WC and its composite catalysis in chemical reactions, the electrochemical behaviors and kinetic characteristics of nitro-compounds on WC and its composite electrodes are studied by electrochemical test techniques, the morphology of WC and its composite electrodes are characterized by SEM and XRD.The WC and its composite electrodes prepared by optimum technology are characterized by SEM and XRD. The results show that the surfaces of the electrodes are well-distributed and the catalytic activity mainly comes from WC.The electroreduction behaviors and kinetic characteristics of nitrobenzene and nitromethane on WC and its composite electrodes in acidic and alkali solution are studied in detail through different types of techniques such as cyclic voltammetry, quasi-steady-state polarization, fast linear potential sweep method, chronoamperometry and chronopotentiometry of EG&G Model 273 A electrochemical measurement system. The results show that, in acidic solution, WC and its composite electrodes are good materials to produce Hydrogen. In alkali solution, the activity of WC and its composite electrodes on electroreducing nitrobenzene is much higher than that of Ni electrode. The electrochemical reactions of nitrobenzene on WC and its composite electrodes in alkali solution are controlled mainly by adsorption of reactants or products. Whether in acidic or in alkali solution, the electrochemical reactions of nitromethane on WC electrodes are controlled mainly by the diffusion of reactants. Particle size of tungsten carbide is one of the important factors influencing on the electrochemical reactions. And adding other metals such as Ni can enhance the activity of WC catalyst. Moreover, the affections of temperature, solvent and conductive mesh are also very important. The kinetic parameters tested are showed below: (1) in nitrobenzene reduction system onWC electrode: in acidic solution i0= 3.1 × 10-6A/cm2, an = 0.43; in alkali solution, i?= 9.9 × 10-5A/cm2, a. n = 0.35. (2) in nitrobenzene reduction system on WC-Ni electrode: in acidic solution i0= 1.2 × 10-6A/cm2, an = 0.41 ; in alkali solution i0= 7 × 10-5A/cm2,a n=0.42. (3) in nitromethane reduction system on WC electrode: in acidic solution i0=2.9×10-5A/cm2, an = 0.33 ;in alkali solution i0= 1.39×10-4A/cm2, an=0.15.Our works show the excellent activity of WC and its composite electrodes in electroreducing nitro-compounds. It shows that we may take the place of other expensive metals such as Pt as catalyst in the future.