In this study, a new anode based on Pb-0.3%Ag/α-PbO 2 /β-PbO 2 -Co 3 O 4 composite is proposed and its performance is compared with that of the traditional Pb-1wt%Ag anode during long-term zinc electrowinning . The electrocatalytic activity of the new anode for the oxygen evolution reaction (OER) initially decreased and then gradually increased, which was attributed to the phase transition occurring at the surface of the anode, and its corrosion resistance was gradually improved with the progress of electrowinning. Further, the electrochemical characteristics, cell voltage , current efficiency , and energy consumption of the two anodes were evaluated after 16 days of electrowinning. The OER electrocatalytic activity and corrosion resistance of the new anode were observed to be higher than those of the traditional anode. In addition, the cell voltage and power consumption of the new anode were significantly lower than those of the traditional anode. Furthermore, compared to the traditional anode, the energy consumption for producing 1 t of zinc was reduced by 358.13 kWh based on the new anode.
Tongtong Li,Yongxin Lu,Shuaishuai Zhao,Zhi-Da Gao,Yan-Yan Song
The development of catalysts based on non-precious metals that are able to catalyze both the oxygen reduction and oxygen evolution reactions (ORR/OER) is the key element to promote the practical application of rechargeable metal–air batteries. Here we report a novel concept that layered double hydroxides (LDHs) can be used as a precursor to form bimetals and their oxides simultaneously. Co3O4-doped Co/CoFe nanoparticles integrated with graphitic shells are derived from the thermal decomposition of a CoFe LDH bonded with urea as the carbon precursor. The composite material shows a surprisingly high bifunctional (ORR/OER) catalytic activity. The realized core–shell structure synergistically promotes the ORR performance while cobalt oxide doped on the metal surface boosts the OER performance. In addition, the carbon shell ensures high electrical conductivity and effectively impedes the aggregation and the further oxidation of Co/CoFe nanoparticles. When integrating the catalyst into a rechargeable Zn–air battery, the battery performance shows a higher discharge potential and cycling stability (over 65 h of cycling) and a lower charge plateau compared with a Zn–air battery based on a Pt/C and RuO2 catalyst mixture. This work demonstrates a new efficient air cathode material which could be practically applied to rechargeable metal–air batteries or other fuel cells.
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