Various noble metals have been utilized as catalysts for urea oxidation. Metal oxides such as ZnO, CuO and NiO were also actively investigated because of low cost . Especially nickel oxide-based catalysts have shown excellent electrocatalytic properties. [4] To uniformly load such catalysts on electrodes, various techniques were utilized, such as electrodeposition [5], sputtering [6], brushing [7], spin coating [8], and EPD [9]. Among them, electrophoretic deposition (EPD) can offer versatile, simple, economic technique. It is also easy to adjust the coating thickness with achieving uniform coating even onto complex-shaped substrates by an electric field. [10] Larger surface area of the catalyst will lead to the higher oxidation current density, which makes easier detection of urea available. [9] By controlling direction and periodicity of the electric field, alternating current (AC) EPD can make tunable rearrangement of particles. [11] Therefore, tuned arrangement of nanostructured particles would control and potentially improve electrochemical properties of urea biosensor.
In this study, NiO nanorods synthesized by hydrothermal method were loaded by EPD technique onto carbon fabric sensing area. In order to investigate the relation between catalytic activity and different morphologies controlled by AC EPD, parameters of frequencies, time and voltage were examined. Structure and morphologies of deposited NiO nanostructures were characterized by XRD and SEM. Cyclic voltammetric measurement was conducted in a three-compartment cell with a potentiostat 1M KOH with 0.33M urea. Chronoamperometric measurement was also performed to assess selectivity and limit of detection. Detailed mechanism and discussion of AC EPD and sensing properties of NiO rod/carbon fabric will be presented.
References
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Acknowledgement
This work was partially supported by Agency for Defense Development (ADD) as global cooperative research for high performance and light weight bio-urine based fuel cell (UD160050BD), and the International Collaborative Energy Technology R&D Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (20158520000210).