Study On The Electrochemical Properties And Application Of Micro-&Nano-Boron Carbide Powder Electrodes

Because of the unique crystal structure of boron carbide （B₄C）, B₄C have manyexcellent properties, such as high melting point, high hardness, low density, good chemicalstability and acid and alkali erosion endurance. A large number of oxygen containingfunctional groups was adsorbed on the surface of B₄C. So B₄C has high chemical activity,which make it has potential to be a new electrode material in electrochemical fields. Inaddition, as a kind of nanomaterials nano-B₄C （NB₄C） has large surface areas and highsurface activity. So it has the great potential to be a catalyst support material.The electrochemical properties of micro-B₄C （MB₄C） powder electrode were studiedby electrochemical measure method. The results showed that MB₄C powder electrode waselectrochemically stable in Na₂SO₄and H2SO4electrolytes, their potential window were1.9V and the background current in magnitude were107A. The electrode reaction wasquasi-reversible and diffusion-controlled in [Fe（CN）₆]^3-/4-redox couple solution or Ce^3-/4-solution.The electrochemical properties of MB₄C powder electrode toward nitrite oxidationwere also studied with cyclic voltammetry curves. The results indicated that MB₄C powderelectrode was proved to be feasible for nitrite analysis and detection. The kineticparameters of the process at MB₄C powder electrode were calculated, i.e. k was1.255×10^-4for the nitrite oxidation. Under the optimum conditions, the oxidation peakcurrent increased linearly with nitrite concentration, the detection limit of NO₂^-was1.533×10^-8mol/L （S/N=3）. In the experiment, it is also feasible that using MB₄C powderelectrode for analysis and detection of phenol. In the phenol solution, the oxidation peakcurrents were direct proportion to concentrations of phenol.Pt-modified NB₄C was prepared by a microwave heating glycol method, theelectrochemical measurements indicated that Pt/NB₄C had excellent catalytic performancefor methanol oxidation. The results suggested that NB₄C described as carrier was feasible.Pt nanoparticles were small and uniform with the mean size of3⁵nm. Compared withthe electrocatalytic activity of different size of B₄C suppored Pt nanoparticles, the specific surface area and the catalytic activity for methanol electrooxidation increased as theparticle size of B₄C decreased, in which the Pt/NB₄C had the higher methanolelectrocatalytic properties.Under the same Pt load, Pt/NB₄C had a greater effectiveelectrochemical surface area than Pt/Vulcan XC-72R catalyst. The results demonstratedthat Pt/NB₄C catalyst exhibited better methanol electrocatalytic activity. In addition, inorder to alleviate the CO poisoning effect and electrocatalytic properties of catalyst,PtRu/NB₄C catalyst was prepared by microwave heating, the alloyed PtRu nanoparticleswere small and uniform with the mean size of2⁴nm. Compared with Pt/NB₄C catalyst,PtRu/NB₄C catalyst exhibited better tolerance of CO poisoning and higher electrocatalyticproperties.