Effect of precursor baking on the electrochemical properties of IrO2-Ta2O5/Ti anodes

IrO2-Ta2O5/Ti anodes were thermally pretreated by means of baking and continuous heating, and then thermal decomposition at 450 degrees C for 30 min. To prepare an IrO2-Ta2O5/Ti anode, a Ti substrate was dipped in the precursor, baked at 80 or 90 degrees C for different periods, and then thermally decomposed at 450 degrees C for 30 min in the air furnace. The electrochemical properties of prepared IrO2-Ta2O5/Ti anodes were evaluated through their voltammetric charges measured in the 1 M H2SO4 solution and their performance lives tested with 2 Acm(-2) in the 1 M H2SO4 + 0.5 M Na2SO4 solution. Microstructures of prepared IrO2-Ta2O5/Ti anodes were characterized with x-ray diffractometer. The chemical compositions and surface morphologies of prepared IrO2-Ta2O5/Ti anodes were analyzed with scanning electron microscope equipped with energy-dispersive x-ray spectrometer. Based on the results of x-ray diffraction, only IrO2-diffracted peaks were detected from prepared IrO2-Ta2O5/Ti anodes. A mud-crack surface structure was seen from prepared IrO2-Ta2O5/Ti coatings. The crack density and the crack width of an IrO2-Ta2O5/Ti coating were obviously affected by different thermal pretreatments of baking methods and heating rates. The crack width of IrO2-Ta2O5/Ti coating increased with an increasing the baking time. A relatively high voltammetric charge can be found from the IrO2-Ta2O5/Ti anode with wide cracks and high crack density. On the other hand, long lifetime values were detected from the IrO2-Ta2O5/Ti anode with a crack width more than 2 mu m. The highest voltammetric charge was detected from the IrO2-Ta2O5/Ti anode prepared through baking at 90 degrees C for 180 s. On the other hand, the longest lifetime was found from the IrO2-Ta2O5/Ti anode pretreated with continuous heating at a rate of 7 degrees C/min.