Observing the in situ chiral modification of Ni nanoparticles using Scanning Transmission X-ray Microspectroscopy

Watson, DJ, acharya, SA, nicklin, RE and Held, G (2014) Observing the in situ chiral modification of Ni nanoparticles using Scanning Transmission X-ray Microspectroscopy Surface Science.

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Abstract

Enantioselective heterogeneous hydrogenation of C=O bonds is of great potential importance in the synthesis of chirally pure products for the pharmaceutical and fine chemical industries. One of the most widely studied examples of such a reaction is the hydrogenation of β-ketoesters and β-diketoesters over Ni-based catalysts in the presence of a chiral modifier. Here we use scanning transmission X-ray microscopy combined with near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS) to investigate the adsorption of the chiral modifier, namely (R,R)-tartaric acid, onto individual nickel nanoparticles. The C K-edge spectra strongly suggests that tartaric acid deposited onto the nanoparticle surfaces from aqueous solutions undergoes a keto-enol tautomerisation. Furthermore, we are able to interrogate the Ni L2,3-edge resonances of individual metal nanoparticles which, combined with X-ray diffraction (XRD) patterns showed them to consist of a pure nickel phase rather than the more thermodynamically stable bulk nickel oxide. Importantly, there appears to be no “particle size effect” on the adsorption mode of the tartaric acid in the particle size range ~90 - ~300 nm.

Item Type:	Article
Divisions :	Surrey research (other units)
Authors :	Watson, DJ, acharya, SA, nicklin, RE and Held, G
Date :	4 April 2014
DOI :	10.1016/j.susc.2014.03.018
Uncontrolled Keywords :	enantioselective hydrogenation, tartaric acid, chiral modifier, NEXAFS, heterogeneous catalysis
Depositing User :	Symplectic Elements
Date Deposited :	28 Mar 2017 13:10
Last Modified :	24 Jan 2020 12:21
URI:	http://epubs.surrey.ac.uk/id/eprint/805452

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