Reversible bifunctional air electrode catalyst
A catalyst, two-electron technology with applications in nanotechnology for materials and surface science, electrical components, electrochemical generators, etc.
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example 1
[0190] Materials and methods
[0191] Electrode preparation:
[0192] Three 5mm diameter disc electrodes were purchased at Pine Research Instrumentation (Durham, NC, USA) for the following studies: Polycrystalline Gold (Pine Research Instrumentation Part No. AFE2A050AU, used at room temperature; Part No. AFE5TO50AUHT, for high temperature use); glassy carbon (part number AFE2A050GC), for room temperature use; and polycrystalline platinum (part number AFE5TO50PTHT), for high temperature use. The polycrystalline metal electrodes were mechanically cleaned by polishing with 5 μm alumina powder followed by 0.05 μm powder polishing (Bühler, Düsseldorf, Germany). The mechanically cleaned metal electrodes were then electrochemically cleaned by cyclic voltammetry with a scan range of 2.2 V and a scan rate of 50 mV / s in 0.1 M HClO4 acidic electrolyte to remove covalently bound compounds. The electrodes were also subjected to multiple scan cycles in the normal electrochemical window un...
example 2
[0206] Oxygen Reduction on Cobalt-Salen-Modified Gold Electrodes
[0207] The polycrystalline Au electrodes were mechanically and electrochemically cleaned as described in Example 1. It was then tested in a pure alkaline electrolyte solution (1M oxygen saturated KOH). 10 μl of 1 M KOH + 2 mM cobalt salen solution was deposited on the electrode surface and then dried for 30 minutes to form a thin film. The thin film modified electrode was placed back into the alkaline electrolyte solution. figure 1 The comparison of electrode ORR CV before and after modification with cobalt salen films is shown.
[0208] figure 1The CVs are displayed indicating that the modified Au electrode (solid CV) undergoes a two-electron reversible oxygen reduction reaction. In the solid line CV (cyclic voltammetry), oxygen reduction occurs in the cathodic scan and oxygen evolution occurs in the anodic scan. For the unmodified Au electrode (dashed line), there is oxygen reduction in the cathodic scan...
example 3
[0212] The role of pH and temperature
[0213] temperature:
[0214] The catalytic activity of gold electrodes in oxygen-saturated cobalt-salen-containing alkaline electrolyte (1M KOH + 2mM cobalt-salen) was measured at three different temperatures: 25°C, 50°C and 70°C. The catalyst has a higher reduction current density at 50°C and 70°C than at 25°C. This higher reduction current occurs at least as a result of further reduction of hydroperoxides to hydroxides. Also, the catalyst has a steeper reduction curve at 70°C than at 50°C, indicating that the chemisorption of hydroperoxides on the Au surface is promoted at high temperature. Furthermore, the anodic peak current density decreases with increasing temperature, which is believed to be due to the decrease in peroxide production. Since the catalytic activity of pure polycrystalline gold electrodes for peroxide generation also changes substantially with increasing temperature, this similar data for the gold / cobalt-salen com...
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