Positive electrode assembly preparation

Cut a 6 x 9V2 inch piece from the Monel wire cloth according to the layout on page 108. This will be the outer oxygen electrode and will follow closely the inside surface of the PVC pipe. 

Cut four silicone rubber rib spacers Vs thick, by /4 wide, by 6 long. Cement these strips with silicone or epoxy to the inner walls of the electrolyzer chamber more or less equidistant from each other, with one end of the strip lining up with the bottom edge of the pipe. Be sure not to cover over the positive electrode port 

Glue rubber spacers on the inside of the electrolyzer tube 

The next step is to make washers for the positive electrode assembly. These are two nickel alloy washers and two silicone rubber washers. Use a 1 diameter washer as a model to trace the circumference and center hole onto the rubber and the nickel alloy sheet. Use a punch to cut out the center hole in the rubber sheet, and a punch or drill to cut out the center hole on the nickel alloy. The circumference of the rubber sheet can be cut with an exacto knife and the circumference of the nickel washer can be cut with tin snips. 

After the rib spacers glue has set, roll the 6 x sVz monel mesh screen into a cylinder (6 long) that can be slipped into the electrolyzer body. 

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In order to remove the reaction by-products and other impurities the as-prepared nanociystals were precipitated by the addition of non-solvent (typically, 2-Propanol) and redissolved in pure water. Indium tin oxide (ITO) coated glass slides (13 Ohm/cm thickness of ITO layer of 125 nm, unpolished, Merck) were used as substrates for LbL assembly and as transparent positive electrodes. Aluminium layers evaporated with a lab coating machine B30.3-T (Malz Schimdt) play a role of cathode. PL measurements were performed at room temperature using a FluoroMax-2 spectrofluorimeter (Instruments SA). Electroluminescence spectra were measured with the same device by positioning the NEED in the focus of the detecting channel. 

If the voltammogram obtained does not show any peak and the base current is sufficiently low (300 00 nA), then it is possible to continue with the analysis of the samples, otherwise the Hg film is destroyed and prepared again. To avoid alteration of the complexation equilibria due to residual ionic Hg and to clean the electrode assembly, the latter is rinsed with a purged aliquot of the sample before transferring the cell cup containing the sample in the measurement position. 

The obtained a-PbO particles are of median diameter of 0.530 pm [26]. Karami and collaborators [27] conducted the chemical reactions in the presence of ultrasonic waves (sono-chemical method) with the aim to reduce the size of the resultant particles. Under these conditions, a-PbO particles of 20—40 nm particle size are obtained. The thus synthesised PbO powder is used for the manufacture of positive plates for small laboratory test cells. Commercial negative plates are used as counter-electrodes. The test cells are set to cycling along with analogous cells assembled with commercial plates prepared with ball mill leady oxide. Figure 5.16 presents the obtained cycling test results for the two types of cells. 

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