resumo
The reactivity of metallic nanotubes toward the catalysis of water dissociation, a key step in the water gas shift reaction (WGSR), was analyzed through density functional theory (DFT) calculations. Water dissociation was studied on surfaces of nanotubes based on copper, gold and platinum, and also on platinum doped copper and gold nanotubes. Gold and copper nanotubes present activities that are similar to those of their corresponding extended surfaces but, in the case of the Pt(5,3) nanotube, a significant improvement in the activity is found when compared with the extended surfaces. In fact, the calculations predict the water dissociation to be spontaneous on Pt(5,3) with a low activation energy barrier. The platinum doping of gold and copper nanotubes leads to contrasting effects, i.e., with a slight increase of activity found on gold and a slight decrease of activity in the case of copper. The consideration of a Bronsted-Evans-Polanyi (BEP) relationship to estimate the activation energy barriers for the O-H bond break leads to a satisfactory agreement between estimated and explicitly calculated values which suggests the validity of the BEP relationship for qualitative predictions of the activities of metal nanotubes towards the water dissociation reaction.
palavras-chave
WATER-GAS-SHIFT; DENSITY-FUNCTIONAL THEORY; TOTAL-ENERGY CALCULATIONS; WAVE BASIS-SET; MOLECULAR-DYNAMICS; TRANSITION-METALS; GOLD NANOTUBES; PARTICLE-SIZE; CATALYSTS; SURFACES
categoria
Chemistry; Physics
autores
Fajin, JLC; Cordeiro, MNDS; Gomes, JRB
nossos autores
José Luis Cagide Fajín
Bolseiro de pós-Doutoramento
José R. B. Gomes
Investigador Principalagradecimentos
This work was developed within the scope of the projects CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER007679 (FCT Ref. UID/CTM/50011/2013), LAQVgREQUIMTE, POCl/01/0145/FEDER/007265 (FCT UID/QUI/50006/2013 and NORTE-01-0145-FEDER-000011), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. J. L. C. F., J. R. B. G. and M. N. D. S. C. also acknowledge FCT for the grant SFRH/BPD/105650/2015 co-financed by the Programa Operacional Potencial Humano (POPH)/Fundo Social Europeu (FSE) and Quadro de Referencia Estrategico Nacional 2009-2013 do Governo da RepUblica Portuguesa, for the Programme Investigador FCT, and for the grant SFRH/BSAB/127789/2016, respectively.