Inner and Outer Surface Areas, Electrochemical Porosity, and Morphology Factor of Mixed Oxide-Covered Mesh Electrodes with a Nominal Composition of MOME-Sn_0.5Ir_xRu(_0.5-x)O₂

摘要

Mixed oxide-covered mesh electrodes containing Sn, Ru, and Ir with a nominal composition of Sn0.5IrxRu(0.5?x)O2 were prepared by thermal decomposition. The oxide films were supported on stainless-steel fine meshes to generate fluid-permeable electrodes for use in solid polymer electrolyte (SPE) reactors. The surface properties, compositions, and structural properties of the mixed oxides were assessed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques, respectively. The SEM study showed that the mixed oxide coatings had a rough superficial morphology with several cracks and/or fissures. The EDS data revealed a small discrepancy between the nominal and true concentrations of different elements in the ternary mixture, which was attributed to the stock solutions containing precursor salts. From the XRD spectra, it was evident that the mixed oxide thin films display good crystallinity and resulted in formation of a solid solution. Cyclic voltammetry (CV) in acidic solution revealed reversible pseudocapacitive voltammetric behaviour of solid-state surface redox transitions (RuIII/RuIV and IrIII/IrIV). In situ surface characterisation of the mixed oxide thin films based on CV and consideration of the intensive dimensionless parameters electrochemical porosity (?) and morphology factor (?) demonstrated that substituting Ru with Ir in the ternary mixture caused variations in the surface morphology of the electrodes. A linear correlation was verified between the parameters ? and ?.