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

Abstract

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.

Polyoxometalates (POMs): from electroactive clusters to energy materials

“…It is also noteworthy that a Ba-Co 9 /lead composite has been investigated recently as anode for OER during zinc electrowinning. 201 The OER is the most common anode or counter reaction in the electrowinning of metals from acidic electrolytes. Zn electrowinning consumes a lot of electrical energy due to the high η O2 , so even a modest decrease in the η O2 would be beneficial for industry to save energy.…”

Electrochemical Behaviors of MnO2 on Lead Alloy Anode during Pulse Electrodeposition for Efficient Manganese Electrowinning

“…Insoluble lead alloy anodes are widely used for electrometallurgy owing to their high conductivity and advantageous corrosion resistance in acidic sulfate solutions, − one of which is manganese (Mn) electrowinning process. , Manganese is an important industrial material used as an additive for the production of raw steel and special alloys in nonferrous metallurgy. − Mn metal is conventionally produced from an electrolytic reduction of manganese and ammonium sulfate solution in a diaphragm cell. Pb (99%) and 1% Ag alloy is a typical anode material for Mn electrowinning .…”

A novel CF/Ti/β-PbO2 composite anode for zinc electrowinning: preparation, electrochemical properties and application

“…The oxygen evolution process of zinc electrodeposition anode can be expressed using formulas (10) and (11). The composition and temperature conditions of the industrial zinc electrowinning solution were substituted in the Nernst formula (12), and the equilibrium oxygen evolution potential under this condition was obtained as 1.2587 V ( vs. SHE).2H 2 O = O 2 + 4H + + 4e E (H 2 O/O 2 ) θ = 1.229 V vs. SHI η 2 = E + 0.2373 − 1.2587 − jR s η 2 = a + b lg j where E is the oxygen evolution potential ( vs. SCE), the electrode potential of the reference electrode at 35 °C is 0.2373 ( vs. SHE), R s is the solution resistance, E (H 2 O/O 2 ) is the standard potential of oxygen evolution under acidic conditions, 38 and j is the current density. The exchange current density ( j 0 ) at η 2 = 0 can be obtained using formulas (13) and (14).…”