Issue 2, 2008
From the journal:

Physical Chemistry Chemical Physics

Redox properties of undoped 5 nm diamond nanoparticles

Katherine B. Holt,*a   Christoph Ziegler,a   Daren J. Caruana,a   Jianbing Zang,b   Enrique J. Millán-Barrios,c   Jingping Hud  and  John S. Foordd  

* Corresponding authors

a Department of Chemistry, University College London, 20 Gordon St., London, UK
E-mail: k.b.holt@ucl.ac.uk

b State Key Laboratory of Metastable Materials Science and Technology, College of Material Science and Engineering, Yanshan University, Qinhuangdao, P.R. China

c Facultad de Ciencias, Departmento de Quimica, Grupo de Electroquímica, Universidad de Los Andes, Mérida, Venezuela

d Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, UK

Abstract

This paper demonstrates the promoting effects of 5 nm undoped detonation diamond nanoparticles on redox reactions in solution. An enhancement in faradaic current for the redox couples Ru(NH3)63+/2+ and Fe(CN)64–/3– was observed for a gold electrode modified with a drop-coated layer of nanodiamond (ND), in comparison to the bare gold electrode. The ND layer was also found to promote oxygen reduction. Surface modification of the ND powders by heating in air or in a hydrogen flow resulted in oxygenated and hydrogenated forms of the ND, respectively. Oxygenated ND was found to exhibit the greatest electrochemical activity and hydrogenated ND the least. Differential pulse voltammetry of electrode-immobilised ND layers in the absence of solution redox species revealed oxidation and reduction peaks that could be attributed to direct electron transfer (ET) reactions of the ND particles themselves. It is hypothesised that ND consists of an insulating sp3diamond core with a surface that has significant delocalised π character due to unsatisfied surface atoms and C[double bond, length as m-dash]O bond formation. At the nanoscale surface properties of the particles dominate over those of the bulk, allowing ET to occur between these essentially insulating particles and a redox species in solution or an underlying electrode. We speculate that reversible reduction of the ND may occur via electron injection into available surface states at well-defined reduction potentials and allow the ND particles to act as a source and sink of electrons for the promotion of solution redox reactions.

Graphical abstract: Redox properties of undoped 5 nm diamond nanoparticles

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Article information

DOI
https://doi.org/10.1039/B711049A
Article type
Paper
Submitted
18 Jul 2007
Accepted
04 Oct 2007
First published
22 Oct 2007

Phys. Chem. Chem. Phys., 2008,10, 303-310

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Redox properties of undoped 5 nm diamond nanoparticles

K. B. Holt, C. Ziegler, D. J. Caruana, J. Zang, E. J. Millán-Barrios, J. Hu and J. S. Foord, Phys. Chem. Chem. Phys., 2008, 10, 303 DOI: 10.1039/B711049A

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