Ag doping to boost the electrochemical performance and corrosion resistance of Ti/Sn-Sb-RuOx/α-PbO2/β-PbO2 electrode in zinc electrowinning

Ag doped beta-PbO2 anode material was prepared on Ti/Sn-Sb-RuOx/alpha-PbO2 through electrodeposition technique to improve its electrochemical properties and corrosion resistance in zinc electrowinning. The chemical composition and surface morphology of the anodes were characterized by X-ray diffraction, Xray photoelectron spectroscopy and scanning electron microscopy. The electrochemical properties and corrosion resistance of the anode materials were established via linear sweep voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy and accelerated life tests. Results showed that the grain size of beta-PbO2 increased with AgNO3 concentration while Ag+ was oxidized to Ago and adsorbed on the electrode surface to accelerate the growth of beta-PbO2 grains. We also proposed the nucleation/deposition mechanism of beta-PbO2 electrode while verifying the role of Ag ion doping. The optimum electrocatalytic performance could be achieved when the concentration of AgNO3 was 6 g L-1. Compared with that of the undoped pure beta-PbO2 anode, the oxygen evolution potential of the Ti/Sn-Sb-RuOx/alpha PbO2/Ag-F-beta-PbO2 was decreased by 64 mV. The service life of the doped F-Ag-beta-PbO2 anode could reach up as high as 249 h, which was 1.66 times of pure beta-PbO2 anode. (C) 2019 Elsevier B.V. All rights reserved.