The carbon nanotubes supported palladium(Pd/CNT)nanocatalysts were modified by cerium oxides/ hydroxides and their catalytic performances for methanol oxidation were evaluated.Electrochemical measurements indicate that the introduction of cerium remarkably improves the catalytic activity of Pd/CNT catalysts towards methanol oxidation.X-Ray photoelectron spectra results reveal an interaction between palladium and cerium oxides.It is also observed that cerium-modified catalysts have excellent poison resistances,which is attributed to the poison-removal ability of cerium oxides/hydroxides.The highly oxidized cerium oxides/hydroxides have a strong ability to inhibit the accumulation of carbonaceous intermediates on the active sites of Pd catalysts.
Vanadium battery has fast and large capacity charge and discharge characteristics,and the concentration and stability of the battery electrolyte are the key to the electrolyte performance.In actual,with higher acidity and higher concentration of the vanadium battery electrolyte,the ion-pair is dominant.The ion-pair dissociation constant is one of the important thermodynamic data related to battery performance.The vanadyl sulfate conductivity in aqueous solution was determined using the conductance method at 298.15 K.Using the origin data fitting,the limiting molar conductance is obtained,and then by the improved Ostwald dilution law and the Davies equation,the activity coefficient is solved so as to obtain the ionic strength of the true solution.Using the Fuoss method,the dissociation constant of vanadyl sulfate ion-pair was calculated.At last,the vanadyl sulfate limiting molar conductance(A_0) is 174.8251748 S·dm^2·mol^(-1),and the vanadyl sulfate ion-pair dissociation constant K_d is0.002636367,and then other thermodynamic properties can be studied.
