La-doped MnCo2O4.5 modified Ti/SnO2-Sb2O4/PbO2 anode for enhancing the electrochemical performance in zinc electrowinning

Abstract

The traditional Pb-Ag anodes used in zinc electrowinning exhibit high overpotential for oxygen evolution reaction (OER) and poor mechanical strength, leading to high energy consumption. To overcome the shortcomings, Ti/SnO₂-Sb₂O₄/PbO₂-La-doped MnCo₂O_4.5 composite anode was prepared by this work. It demonstrated enhanced electrochemical performance, requiring 565 mV to reach the benchmark current density of 50 mA cm⁻², and the Tafel slop of 179.79 mV dec^–1 in the acidic media containing 50 g L^–1 Zn²⁺ and 150 g L^–1 H₂SO₄. According to the results of XPS, the content of Mn⁴⁺ and Co³⁺ increased, which was beneficial to promote the OER catalytic activity of the electrode. The current efficiency was improved by 1.7 % compared with traditional Pb-0.76 % Ag anode, resulting in a significant reduction in energy consumption of 477.46 kW∙h for producing one ton of zinc. Moreover, the Ti/SnO₂-Sb₂O₄/PbO₂-La-doped MnCo₂O_4.5 anode showed excellent corrosion resistance, and the accelerated service time was extended to 50 h at 2 A cm⁻². The service life of the electrode was extended thanks to the introduction of the intermediate layer and La-doped MnCo₂O_4.5 powder. Therefore, this work provided a novel strategy to prepare the anodes with enhanced electrochemical performance applied in zinc electrowinning and other aspects.