Low-Temperature Catalytic Reactivity of Nanodiamond in Molecular Hydrogen
Ashek-I-Ahmed1*, Soumen Mandal2, Laia Gines2, Oliver A. Williams2, Chia-Liang Cheng1
1Department of Physics, National Dong Hwa University, Hualien, Taiwan
2Department of Physics and Astronomy, Cardiff University, Cardiff, UK
* presenting author:ASHEK AHMED, email:ashekiahmed@gmail.com
Nanometer-size diamond particles, extracted first from the primitive meteorite, has, over the past two decades, got remarkably potential in diverse areas of research owing to its unique physical, optical and surface chemical properties. Intense luminescence without photo-bleaching, high surface area and adaptive chemical reactivity, and non-cytotoxicity enable nanodiamond (NDs) to a great extent in various biomedical applications such as drug delivery, imaging or bio-labeling etc. Surface hydrogenation of nanodiamond under gas treatment is a widely accepted technique to provide least surface contamination with maximum homogeneity, colloidal particle size distribution, and the feasibility to be the primary bio-chemical linker. In this paper, we report the reaction dynamics of hydrogen termination on nanodiamond annealing at low temperature (500C) in hydrogen atmosphere. We analyzed the mass spectroscopic measurement of residual gas using a residual gas analyzer (RGA) while ultra-disperse diamond (UDD) particles of grain size ~4 nm were annealed at 500C under ultra-high vacuum (UHV). It was found that annealing UDD results in C3 –radical desorption and that incites a free radical reaction through the reduction of molecular hydrogen to atomic hydrogen under gas flow. Consequently, as released atomic hydrogen facilitates C-H adsorption on the surface of UDD and the effect was characterized using FTIR spectroscopy. This study can open a wide range of applications of nanodiamond from bio-medical to diamond thin film growth.

Keywords: Nanodiamond , Low-temperature, Catalyst , Carbon -radical, Hydrogenation