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

• Published in: Journal of hazardous materials 2022-04, Vol.428, p.128212-128212, Article 128212
• Main Authors: Wang, Xuanbing, Wang, Junli, Yu, Bohao, Jiang, Wenhao, Wei, Jinlong, Chen, Buming, Xu, Ruidong, Yang, Linjing
• Format: Article
• Language: English
• Subjects: Energy-saving; MnCo2O4.5@C; OER; PbO2; Zinc electrowinning
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.128212

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 MnCo2O4.5@C modified PbO2 electrode through the pyrolysis and co-electrodeposition as a promising candidate for zinc electrowinning. As a result, the obtained Pb-0.2%Ag/α-PbO2/β-PbO2-MnCo2O4.5@C composite electrode showed a sandwich-like structure, where Pb-0.2%Ag as a core, α-PbO2 as a mid-layer, and β-PbO2-MnCo2O4.5@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 Zn2+ and 150 g L−1 H2SO4. 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-PbO2/β-PbO2-MnCo2O4.5@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. [Display omitted] •MoCo2O4.5@C modifying PbO2 composite electrode was prepared through pyrosis-annealing and electrodeposition.•The overpotential at 50 mA cm−2 of composite electrode was decreased by 353 mV as compared with Pb-0.76%Ag alloy.•The composite electrode had a long service life of 44 h when tested at 2 A cm−2.•As compared to Pb-0.76%Ag alloy, the energy consumption of composite electrode for one-ton zinc was lowered by 283.5 kW h.