Nanodiamond thin films on titanium substrates: Growth and electrochemical properties

• Published in: Journal of the Electrochemical Society 2003, Vol.150 (1), p.E59-E65
• Main Authors: LAU CHI HIAN, GREHAN, Kieron J, COMPTON, Richard G, FOORD, John S, MARKEN, Frank
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1528203

A new type of electrically conducting nanosized diamond film deposit is grown on titanium substrates in a microwave plasma chemical vapor deposition process. The deposition process occurs at 80 Torr in a helium atmosphere with only hydrogen (1.95%) and methane (0.73%) admitted and yields a deposit growing approximately 0.5 mu m h exp -1 thick. Electron microscopy indicates the formation of nanosized diamond platelets. The electrochemical properties of nanodiamond when immersed in aqueous electrolyte solution are explored for the Fe(CN) sub 6 exp 3-/4- System, the Ce exp 4+/3+ system, the oxidation of hydroquinone, ascorbic acid, and the oxidation of dihydronicotinamide adenine dinucleotide. Compared to boron-doped diamond materials, nanodiamond is a highly active electrode material with very low overpotentials for all redox systems studied. For ascorbic acid, diffusion-controlled oxidation is detected at potentials approximately 0.5 V more negative compared to those observed at boron-doped diamond electrodes. The electrical conductivity, high surface reactivity, and electrochemical characteristics are explained in terms of many defects and active surface sites.