Effect of carbon chain length of chlorinated carboxylic acids on morphology of the carbon films electrodeposited from aqueous solutions

Diamond-like carbon films can be electrodeposited from organic acids in aqueous solutions. Chlorinated carboxylic acids with different chain lengths, ie. chloroacetic acid , 3-chloropropionic acid, 4-chlorobutyric acid and 5-chlorovaleric acid, were used as the carbon sources in the electrolytes. It showed an interesting even-odd effect of carbon chain length on the surface morphology of the electrodeposited carbon films. The odd carbon-numbered chlorinated carboxylic acids lead to smooth carbon films whose morphologies were insensitive to the deposition parameters. On the contrary, the morphologies of the films obtained from the even carbon-numbered chlorinated carboxylic acids were island-like and dependent on the film thickness. Fourier transform infrared and Raman analysis indicated that the electrodeposited diamond-like carbon films were hydrogenated and contaminated by oxygen.