The Electrochemical Behaviors Of Alkaline BH₄^- On Pt Ni Cu Anode

Borohydride as fuel for fuel cell has attracted much attention due to its high theoretical electromotive force and specific energy in recent years. Theoretically, one ion of BH₄^- can generate eight electrons, however, in the fuel cell course of work, the sodium borohydride carries out direct oxide reaction on different anodes, While borohydride hydrolysis reaction is in progress, hydrogen generation will reduce fuel efficiency, so the number of electrons generated by per ion of BH₄^- oxidized is different due to the different anode electrocatalysts. Noble metals used as the anode materials showed high catalytic activities, but it will be not in favor of reducing cost of DBFC. In this paper, we want to explore the possibility that low-cost metal is used as the anode materials in the borohydride fuel cell.In this dissertation, the electrochemical behavior of NaBH₄ alkaline solution on platinum, nickel and copper was studied by cyclic voltammetry. The results showed that the sodium borohydride direct oxidation reaction on platinum and copper electrode can be well happening, in the presence of TU, hydrolysis reaction of BH₄^- can be inhibited, It is proposed that TU could improve the BH₄^- utilization efficiency.Furthermore, the effects of anode material, membrane and concentration of borohydride on the performance of direct borohydride fuel cell were investigated. Liner polarization was used to study the electrochemical behavior of NaBH₄ on copper. Experimental DBFC was constructed by different anodes, Pt cathode and cationic membrane. The results showed that the performance of direct borohydride fuel cell on platinum was better than that on nickel and copper, Nickel electrode can not be the electrode material of sodium borohydride direct oxidation. The NRE-212 membrane showed a higher performance than the CM-001 membrane at the same NaBH₄ alkaline solution. In a anolyte of 2.0mol·L^-1 NaBH₄ and 2.0mol·L^-1NaOH , a maximum current density and a maximum power density at room temperature reached to 235mA/cm² and 46.14mW/cm² respectively when copper was used as anode. The life test was carried out galvanostatically at a current density of 20mA/cm² and the cell voltage was stabile at 0.6V in 50hours. SEM, EDS and XRD were used to characterize the Cu electrode, the results showed that composition of anode was still Cu simple substance although surface morphology of anode changed obviously during the experiment.