I've browsed some publications, but few mention the details like the concentration of the agent, temperature, etc. Can anyone provide suggestions or a protocol?
I use H2SO4 (0.1M) at 1600mV during 180s to generate carboxylic groups at the surface of screen printed carbon electrode. Attention! with glassy carbon potential is too high.
Hi,
These functional groups are formed in more or less severe conditions, as they are more or less stable. I would not prepare them directly by electrochemical oxidation, as the potential for forming them is indeed prone to change, depending on the carbon texture. I would instead oxidise as much as possible, thus forming all possible oxidised functions. For that purpose, concentrated H2O2, HClO or HNO3 in water all work well. Then, a heat-treatment in nitrogen at increasingly high temperatures first makes carboxylic acids evolve, followed by carbonyls at higher temperature, followed by hydroxyls at the highest temperature. But it is extremely difficult to have one single kind of moiety remaining at the surface. Except for -OH groups, for which oxidation, evolution of carboxylic acid, and selective reduction by NaBH4 in dry solvent works very well (see attachement).
Alain
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