Lead dioxide (PbO 2 ) nanoparticles are electrodeposited on lead anode, using pulsed and constant direct current (DC) in 4.8 M H 2 SO 4 solution, to improve active surface area and promote catalytic activity of lead electrode. To increase the yield of PbO 2 nanoparticles, current density, temperature and time of anodization are optimized using the response surface methodology. The optimum condition is found to be 25 mA cm −2 current density, 100°C temperature and 4-hour pulsed DC and 1-hour constant current for anodizing time. To increase the yield of nano β-PbO 2 from 41.62% to 99%, porosity of the lead layer is increased and the passive layer of lead sulfate is broken. For this purpose, the lead substrate is pretreated in an electrochemical bath of sulfuric acid and perchloric acid, followed by immersing the electrode in hydrofluoric and nitric acid. Formation mechanism of β-PbO 2 is also identified.

A novel Pb(II) complex, {[Pb 2 (tpmba) 2 (NO 3 ) 4 ]Á MeOH} n (1), was obtained by the reaction of a tripodal ligand, N,N 0 ,N 00 -tris(pyrid-3-ylmethyl)-1,3,5-benzenetricarboxamide (tpmba), with Pb(NO 3 ) 2 . The structure of complex was determined by X-ray crystallography. The results of structural analysis of the complex reveal that 1 is a M 2 L 2 cage-like with a methanol molecule beside the cage. An entirely different structure and topology between 1 and similar complexes indicate that the nature of organic ligands affects the structure of assemblies. The results indicate that the framework of this complex is predominated by the nature of the organic ligand, anions, solvent and geometric need of the metal ions. It was found that the coordination number of Pb II ions is eight, (PbN 3 O 5 ) has a stereo-chemically active electron lone pair and the coordination sphere is hemi-directed. PbO nanoparticles are obtained by thermolysis of 1 at 180°C with oleic acid as a surfactant. Scanning electron microscopy shows that the size of the PbO particles is *30 nm.

Nowadays, there is a growing interest in synthesizing electrodes used in zinc electrowinning, increasing active surface area, decreasing specific energy consumption, and the oxygen evolution reaction (OER) overpotential. In this study, modified nanocomposite anodes were synthesized by applying pulsed and constant direct current electrodeposition to improve the catalytic activity of the electrodes toward the oxygen evolution reaction (OER) and reduce energy consumption in zinc electrowinning. By decreasing particle size, the active surface area of PbO2–RuO2 nano-mixed composite electrode was 2.88 and 14.22 times greater than PbO2–RuO2 microcomposite and pure PbO2 electrodes, respectively. Also, the anodic polarization of PbO2–RuO2 microcomposite showed a 0.201 V decrease at 0.01 A cm–2 in the OER overpotential as compared to pure micro PbO2. Among the synthesized anodes, the Ti/PbO2–RuO2 nano-mixed morphology composite anode possessed the lowest overpotential and the least specific energy consumption by 0.705 V at a current density of 0.14 A cm–2 and 2.11 kWh kg–1, respectively.