Two-step facile synthesis of Co3O4@C reinforced PbO2 coated electrode to promote efficient oxygen evolution reaction for zinc electrowinning

Abstract

The conventional Pb–Ag alloy possesses a high oxygen evolution reaction overpotential, poor stability, and short service life in acidic solutions, making it an unsuitable sort of anode material for the zinc electrowinning process. Therefore, a layered carbon-covered cobalt tetroxide (Co₃O₄@C)-reinforced PbO₂-coated electrode is fabricated via a facile two-step pyrolysis-oxidation and subsequent electrodeposition process. As a result, the reinforced PbO₂-coated electrode exhibits a low OER overpotential of 517 mV at 500 A m⁻² and a Tafel slope of 0.152 V per decade in a zinc electrowinning simulation solution (0.3 M ZnSO₄ and 1.53 M H₂SO₄). The reduced overpotential of 431 mV at 500 A m⁻² compared to traditional Pb–0.76%Ag alloy leads to improved energy savings, which is attributable to the presence of Co₃O₄@C to refine the grain size and thus increase the effective contact area. Moreover, the reinforced PbO₂-coated electrode has a prolonged service life of 93 h at 20 000 A m⁻² in 1.53 M H₂SO₄. Therefore, an accessible and efficient strategy for preparing a coated electrode to improve OER performance for zinc electrowinning is presented in this research.