Preparation And Properties Of New Type Oxygen Anode

Pb-Ag alloys are widely used as anodes in industrial zinc electrowinning owning to its relatively inexpensive and forming PbO2 protective layer during the electrowinning process. However, the Pb-Ag anodes have some shortcomings such as high oxygen evolution overpotential, easily bending. Therefore it is necessary to develop new kinds of oxygen evolution anode with a higher electro-catalytic activity and stability.Thermodynamic analysis of electrodepositing MnO2 on Pb-Ag (0.3 wt.%) anode from Mn(CH3COO)2 solution was discussed. The effect of both deposition potential and Mn(CH3COO)2 concentration on performance of Pb-Ag anode was investigated. MnO2 activated Pb-Ag anode was prepared and its oxide layer was characterized by XRD and SEM as well as XRF. Moreover, the carbon nanotubes enhanced lead anode (Pb-CNTs anode) was fabricated by powder metallurgy, and its electrochemical performance and surface hardness were studied and compared with pure Pb anode.It was shown that with an increase of Mn(CH3COO)2 concentration, electro-catalytic activity of MnO2 activated Pb-Ag anode increases at first and then decreases, and hardness of MnO2 activated Pb-Ag decreases. When Mn(CH3COO)2 concentration is 0.05mol/L, MnO2 activated Pb-Ag anode with a higher electro-catalytic activity and stability is prepared at a deposition potential 1.15V, and its oxygen evolution overpotential at current density 0.05A/cm2 is lower than that of Pb-Ag anode by about 0.2V, and its surface hardness is 1.659 times higher than that of Pb-Ag anode.The optimum technological conditions for preparation of Pb-CNTs composite powder was explored, which included electrolyte consisting of 0.005mol/L Pb(CH3COO)2, 2.1mol/L CH3COOH,0.6mol/L reagent A,2.0g/L gelatin,0.5g/L SDBS,0.5g/L CNTs, and ultrasonic power 120W, ultrasonic dispersion time 1h, ultrasound-assisted deposition durable time 1h, room temperature, cathodic current density 0.30A/cm2. Oxygen evolution overpotential of Pb-CNTs anode is lower than that of pure Pb anode by about 0.2V, and surface hardness of Pb-CNTs anode is 3.93 times larger than that of pure Pb anode.