The role of ZnFe2O4 in the electrochemical performance of Pb-ceramic composite anode in sulfuric acid solution

Abstract The nonferrous metal electrowinning process is energy intensive due to the sluggish dynamics of the oxygen evolution reaction (OER) on the anode. Developing novel anode materials with high OER activity and stability is imperative. Herein, we propose a novel Pb-ceramic composite anode by introducing ZnFe2O4. In this work, Pb-ZnFe2O4 and PS-Pb anodes were prepared through powder pressing and sintering processes. The effects of ZnFe2O4 particles on the phase composition, surface morphology and inner structure of the oxide layer formed on Pb-ZnFe2O4 anodes were investigated. Furthermore, the role of ZnFe2O4 in the anodic potential and stability of Pb-ZnFe2O4 anodes was discussed. The results show that as the ZnFe2O4 content increases, the oxide layer formed on Pb-ZnFe2O4 anodes exhibits higher surficial compactness, higher integrity, and much smaller thickness. ZnFe2O4 exhibits a trivial impact on the oxygen evolution dynamics. However, the anodic potential of the Pb-ZnFe2O4 anode declines as the ZnFe2O4 content increases, which could be attributed to the higher compactness and smaller thickness of the oxide layer. As the ZnFe2O4 content increases, the weight loss of the Pb-ZnFe2O4 composite anode increases, suggesting the unsatisfactory stability of Pb-ZnFe2O4, which could be attributed to the inevitable dissolution of ZnFe2O4 particles, smaller thickness of the oxide layer and larger porosity of the substrate. Although Pb-ZnFe2O4 composite anodes have the potential to reduce energy consumption, their unsatisfactory stability limits the feasibility of Pb-ZnFe2O4 anodes in the electrowinning industry.