Facile one-step synthesis of a Co3O4- and CNT-doped 3D-Ti/PbO2 electrode with a high surface for zinc electrowinning

Abstract In this paper, a Co3O4- and CNT-doped 3D PbO2 electrode was fabricated through galvanostatic electrodeposition in a Pb(Ac)2-NH2SO3H solution, and the electrochemical properties were systematically investigated in a zinc electrolyte. The XRD results show that the deposit is a mixture of an α + β phase (a dominant β-PbO2 phase with a minor α-PbO2 phase present), and the SEM images show that Co3O4 and CNT have been simultaneously deposited with PbO2. The 3D-Ti/PbO2-(4 g·L−1) Co3O4-(0.4 g·L−1) CNT electrode exhibits a voltammetric charge 5 times larger than that of the 3D-Ti/PbO2 electrode, which indicates outstanding electrocatalytic activity. The oxygen evolution reaction overpotential and cell voltage are only 394 mV and 3.74 V at 500 A∙m−2, respectively. In addition, the obtained electrode showed a high current efficiency of 95.3% and a service life of 26 h under a current density of 20,000 A∙m−2. Hence, this study offers a facial synthesis route to prepare composite electrodes for zinc electrowinning and provides deep insight into the relationship among doping substances, microstructures and electrocatalytic activity.