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DFT-D3 study of H2 and N2 chemisorption over cobalt promoted Ta3N5-(100), (010) and (001) surfaces

Zeinalipour-Yazdi, Constantinos D., Hargreaves, Justin S. J., Laassiri, Said and Catlow, Charles Richard 2017. DFT-D3 study of H2 and N2 chemisorption over cobalt promoted Ta3N5-(100), (010) and (001) surfaces. Physical Chemistry Chemical Physics 19 , pp. 11968-11974. 10.1039/C7CP00806F

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Abstract

The reactants for ammonia synthesis have been studied, employing density functional theory (DFT), with respect to their adsorption on tantalum nitride surfaces. The adsorption of nitrogen was found to be mostly molecular and non-activated with side-on, end-on and tilt configurations. At bridging nitrogen sites (Ta–N–Ta) it results in an azide functional group formation with a formation energy of 205 kJ mol−1. H2 was found also to chemisorb molecularly with an adsorption energy in the range −81 to −91 kJ mol−1. At bridging nitrogen sites it adsorbs dissociatively forming >NH groups with an exothermic formation energy of −175 kJ mol−1 per H2. The nitrogen vacancy formation energies were relatively high compared to other metal nitrides found to be 2.89 eV, 2.32 eV and 1.95 eV for plain, surface co-adsorbed cobalt and sub-surface co-adsorbed cobalt Ta3N5-(010). Co-adsorption of cobalt was found to occur mostly at nitrogen rich sites of the surface with an adsorption energy that ranged between −200 to −400 kJ mol−1. The co-adsorption of cobalt was found to enhance the dissociation of molecular hydrogen on the surface of Ta3N5. The studies offer significant new insight with respect to the chemistry of N2 and H2 with tantalum nitride surfaces in the presence of cobalt promoters.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Advanced Research Computing @ Cardiff (ARCCA)
Cardiff Catalysis Institute (CCI)
Publisher: Royal Society of Chemistry
ISSN: 1463-9076
Funders: EPSRC
Date of First Compliant Deposit: 20 June 2017
Date of Acceptance: 6 April 2017
Last Modified: 13 Aug 2019 12:35
URI: http://orca-mwe.cf.ac.uk/id/eprint/101584

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