Preparation Of Carbon Supports Loaded Catalysts And The Study Of Their Electrocatalytic Behaviors For H₂O₂ And C₄H₄O₄

As a new type of renewable energy,fuel cell has attracted extensive attention.Hydrogen peroxide（H₂O₂）has the advantages of non-toxic and harmless,and convenient transportation,and can be directly used as the fuel for fuel cell and occur electrooxidation reaction in anode region.Maleic acid（C₄H₄O₄）can occur electroreduction reaction and has the potential to be the oxidizer of fuel cell,and the reaction product（succinic acid,C₄H₆O₄）is green and environmental friendly that can be used as an important intermediate in the fields of chemical industry,medicine,biodegradable plastics and so on.The properties of electrode materials have important influences on H₂O₂ electrooxidation and C₄H₄O₄ electroreduction.In this paper,graphite coated filter paper（FG）,carbon paper（CP）and carbon cloth（CC）were used as supports to prepare FG@Co-Co C₂O₄-Ni,CP@Pb and CC@Ti O₂ electrode materials with three-dimensional（3D）,and the obtained three electrode materials were used to catalyze H₂O₂ electrooxidation and C₄H₄O₄ electroreduction,respectively.The morphology and phase composition of the prepared electrode materials were characterized by the instruments of X-ray diffraction（XRD）,scanning electron microscope（SEM）,transmission electron microscope（TEM）,energy dispersive X-ray spectrometer（EDS）,X-ray photoelectron spectroscopy（XPS）and fourier transform infrared spectrometer（FT-IR）and so on,and the electrocatalytic properties of electrode materials were studied by the means of cyclic voltammetry（CV）,chronoamperometry（CA）and chronopotentiometry（CP）.The transition metal Co layer with porous structure is loaded on the FG support by electrodeposition method.The surface structure of the as-loaded Co layer was further modified by etching in oxalic acid（H₂C₂O₄）solution.Finally,Ni nanoparticles were loaded on its surface by electrodeposition process,and FG@Co-Co C₂O₄-Ni electrode with special 3D porous structure was successfully prepared,and its electrooxidation behavior for H₂O₂ was studied.In1.0 mol·dm^-3 Na OH and 0.20 mol·dm^-3 H₂O₂ solution,the oxidation current density of FG@Co-Co C₂O₄-Ni electrode is 270.6 m A cm^-2（0.6 V）.The reaction mechanism of H₂O₂electrooxidation on the surface of FG@Co-Co C₂O₄-Ni electrode was explored.The results show that the Ni compounds and Co compounds were the main catalytic active substances for H₂O₂ electrooxidation.It is worth noting that the preparation process of FG@Co-Co C₂O₄ Ni electrode is simple and it shows good catalytic activity for H₂O₂ electrooxidation,which make it to be a new and efficient H₂O₂ electrooxidation catalyst.The CP@Pb electrode was prepared by electrodeposition method,and the effects of electrodes that obtained under different preparation conditions for the catalytic properties of C₄H₄O₄ electroreduction were studied.The CP@Pb electrode prepared in 0.10 mol·dm^-3 Pb B₂F₈at the potential of-1 V for 120 s shows the best catalytic performance for the electroreduction of C₄H₄O₄.The reduction current density is 191.3 m A·cm^-2（-1 V）in 0.25 mol·dm^-3 H₂SO₄ and0.30 mol·dm^-3 C₄H₄O₄ when the reaction temperature is 318.15 K.The research shows that the electroreduction of C₄H₄O₄ on the CP@Pb electrode surface is a 0.5 order reaction and is controlled by diffusion and follows the electron transfer mechanism.The activation energy calculated of the reaction by Arrhenius equation is 2.6 k J·mol^-1,indicating the energy barrier of catalytic C₄H₄O₄ electroreduction on CP@Pb is low and the reaction is easy to occur.The purity of synthesized C₄H₆O₄ is 96%when the reduction current density is 120 m A·cm^-2.Another effective catalyst for the electroreduction of C₄H₄O₄ was further studied in this paper.Ti O₂ electrode material with CC as the support（CC@Ti O₂）was prepared by hydrothermal method and the electrode material shows a good ability for catalyzing the electroreduction of C₄H₄O₄ in acidic environment.When the potential is-1 V,in the solution containing 0.25 mol·dm^-3 H₂SO₄ and 0.40 mol·dm^-3 C₄H₄O₄,the reduction current density of C₄H₄O₄ catalyzed by the CC@Ti O₂ electrode is 159.9 m A·cm^-2（318.15 K）.The electroreduction reaction of C₄H₄O₄ on CC@Ti O₂ electrode is controlled by diffusion and is a0.5 order reaction.When the reduction current density is 80 m A cm^-2,CC@Ti O₂ electrode catalyzes the electroreduction of C₄H₄O₄ to synthesize C₄H₆O₄ with a purity of 95%.