Preparation And Electrochemical Performance Study Of Co₃O₄and Composite Oxide Nanomaterials

Spinel Co3O4and composite oxides nanomaterials are technologically important multifunctional materials with great applications in sensors, batteries, heterogeneous catalysts and supercapacitors. Nanostructured Co3O4and composite oxides with high specific surface area and enhanced electrochemical activity is particularly attractive for the above-mentioned applications. In the past decade, various nanostructures of cobalt oxides and its composite oxides have been synthesized with many different ways, and their enhanced electroactivities have been demonstrated. Among these nanostructures of Co3O4and its composite oxides, one dimensional (1D) nanostructure has been attracting a great deal of attention due to its excellent properties. In addition, the bonding force between conductive substrates and nanomaterials will directly affect the activity of the materials into full play. So searching for an appropriate method that make nanomaterials directly grow on conductive substrates is more attractive. We report a facile template-free procedure to synthesize freestanding Co3O4nanowire arrays and its composite oxide nanowire arrays on nickel substrate and study their electrochemical performances.In the third chapter, cobalt oxalate nanowire arrays are formed by immersing the electrodeposited Co film on Ni substrates in an oxalic acid solution, and through the thermal treatment of the cobalt oxalate nanowire arrays at250℃results in the formation of Co3O4nanowire arrays. The as-synthesized Co3O4nanowires exhibit a hierarchically porous structure inside their architectures. The Co3O4nanowire array shows a much high sensitivity (318μAmM-1cm-2) and a relatively wide linear range (0.01-6Mm) for the electrochemical detection of H2O2, resulting from the unique hierarchical nanostructure. Then compared with other metal oxides nanomaterials and horseradish peroxidase HRP as the sensor detection H2O2concentration, we can find that our Co3O4nanowire array has the wider linear range and the higher sensitivity.In the fourth chapter, we report the synthesis of mesoporous CoxFe3-xO4NW arrays grown directly on conductive substrates by immersing the electrodeposited Co-Fe alloy film in an oxalic acid solution and their electrocatalytic performance in OER. Test results show that the Co3O4nanowire arrays and CoxFe3-xO4nanowire arrays possess low the oxygen evolution potential, high polarization current and good OER stability and CoxFe3-xO4nanowire arrays possess much lower the oxygen evolution potential (≈0.5V). higher polarization current (≈95mAcm-2) and the better OER stability.