Polymer anode used in hydrometallurgy: Anodic behaviour of PANI/CeO2/WC anode from sulfate electrolytes

In this paper, the polyaniline/ceria/tungsten carbide (PANI/CeO2/WC) composite was designed and investigated by comparing with reported PANI/CeO2 and PANI/WC composites. Their oxygen evolution kinetics, cell voltage, and deposited zinc quality in an electrolyte solution of 65 g·L− 1 Zn2 + and 150 g·L− 1 H2SO4 at 35 °C were investigated by electrochemical impedance spectroscopy, anode polarization curve, galvanostatic electrolysis, scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), and Raman spectroscopy, respectively. The results show the PANI/CeO2/WC anode exhibited reduced overpotential for oxygen evolution (0.896 V at 500 A·m− 2), highest electrocatalytic activity, and lowest cell voltage (2.703 V at 500 A·m− 2) in electrowinning of zinc. It is the result of electro-catalytic synergistic effect between CeO2 and WC solid particles. Moreover, deposited zinc on the cathode is more compact and smooth by using PANI/CeO2/WC anode. It was also found that these characteristic peaks of polyaniline remain (1123 cm− 1, 1480 cm− 1, 1568 cm− 1), which indicates polyaniline was not oxidized after electrolysis. These results demonstrated that the failure of polyaniline composite anode is ascribed to mechanical fatigue instead of polyaniline oxidation.