Facile synthesis MnCo2O4.5@C nanospheres modifying PbO2 energy-saving electrode for zinc electrowinning

The oxygen evolution reaction kinetics in industrial zinc electrowinning is sluggish, resulting in low electrocatalytic activity and substantial energy expenditure (about one-third of energy was wasted due to the strong polarization effect). Herein, the paper described a core-shell structured MnCo 2 O 4.5 @C modified PbO 2 electrode through the pyrolysis and co-electrodeposition as a promising candidate for zinc electrowinning. As a result, the obtained Pb-0.2%Ag/ α -PbO 2 / β -PbO 2 -MnCo 2 O 4.5 @C composite electrode showed a sandwich-like structure, where Pb-0.2%Ag as a core, α -PbO 2 as a mid-layer, and β -PbO 2 -MnCo 2 O 4.5 @C served as an electrocatalytic layer. It also possessed improved OER catalytic activity , only required 680 mV to achieve a current density of 50 mA cm −2 and a Tafel slope of 216.04 mV dec −1 in an acidic solution containing 50 g L −1 Zn 2+ and 150 g L −1 H 2 SO 4 . The current efficiency increased by 0.7% and the cell voltage reduced by 360 mV as compared to a conventional Pb-0.76%Ag alloy electrode, leading to a remarkable energy-consumption reduction of 283.5 kW h for producing per ton metallic zinc. Furthermore, Pb-0.2%Ag/ α -PbO 2 / β -PbO 2 -MnCo 2 O 4.5 @C exhibited a prolonged service life, which worked about 44 h under an ultra-high current density of 2 A cm −2 . Hence, this paper provides the strategy to design and construct non-precious, high-performance catalyst for electrolysis and other applications.