Electrocatalytic Activity of Pd/Ir/Sn/Ta/TiO 2 Composite Electrodes

This study compared the electrolytic refining process using different commercial Pd-based electrodes. The Pd-based electrode had an Ir:Sn molar ratio of 1:1 and contained 10% tantalum on a titanium substrate. The palladium weight ratio varied from 0 g to 1.8 g, 4.7 g, 8.6 g, and 15.4 g. Electrolytic refining was investigated for the Pd-based electrode in 3 M of H 2 SO 4 . The interfacial microstructure and components of the substrate were investigated using energy-dispersive X-ray analysis, and the electrochemical properties of the materials were measured using cyclic voltammetry, linear scan voltammetry, electrochemical impedance spectroscopy, and accelerated life tests. Of all the tested Pd-based electrodes, those with a palladium loading weight of 8.6 g showed the highest and most stable electrode activity at 3 M of H 2 SO 4 , with a capacitance retention of 96% of its initial value. The accelerated life test results for the 8.6 g Pd-Ir-Sn-Ta/TiO 2 electrode showed a gradual slope with an efficiency of almost 100% at 1000 h in an aqueous solution of 3 M of H 2 SO 4 . After the test, the dissolved elements that caused resistance in the electrolyte increased with increasing palladium loading content. Thus, the 8.6 g Pd-Ir-Sn-Ta/TiO 2 electrode demonstrated the optimum composition in 3 M of H 2 SO 4 for electrolyte refining.