Using square wave voltammetry for the electrochemical characterization of cerium oxide/multiwalled carbon nanotube composites in different aqueous electrolytes

Two CeO2/carbon nanotube composites were prepared in both basic and neutral medium thus using different deposition procedures of the cerium oxide. The modification of the synthesis conditions varied the hydrolysis rate of the cerium oxide precursor, leading to materials with different morphology, texture and surface chemistry, significantly changing their electrochemical performance. The different mechanisms of charge storage occurring on the surface of the materials were thoroughly studied to investigate the origin of the observed changes in the electrochemical properties. To that end, a combination of sweep wave voltammetry and deconvolution analysis in acid (1 M H2SO4), basic (1 M NaOH) and neutral (1 M Na2SO4) electrolytes was conducted. The faradaic activity of the composite prepared by slow hydrolysis (containing well-dispersed and small ceria particles) is enhanced as compared with the composite prepared by fast hydrolysis, which originates bulky particles.