Polyoxometalate/Lead Composite Anode for Efficient Oxygen Evolution in Zinc Electrowinning

Oxygen evolution in harsh high-acidic conditions has always been a challenge for both zinc electrowinning and hydrogen production. Lead and its alloys have met the requirements of zinc electrowinning up to now. This is the first time that a polyoxometalate/lead composite as an earth-abundant material has been investigated for use as anode in zinc electrowinning. A polyoxometalate/lead composite showed a high electrocatalytic activity and a long-term durability during an oxygen generation reaction in harsh high-acidic conditions of electrochemical accelerated corrosion tests. It could boost oxygen evolution by decreasing the Gibbs energy barriers of intermediates and showed a 10-fold higher electrochemically active surface area and one fifth of the polarization resistance compared to pure Pb. The overpotential of a Pb anode containing 1 wt% polyoxometalate was similar to that of a commercial Pb/0.75 wt% Ag anode, which implies the potential application of polyoxometalate/lead composite anodes in the hydrometallurgical industry. (C) 2019 The Electrochemical Society.