TY - JOUR
T1 - Influence of particle size and water coverage on the thermodynamic properties of water confined on the surface of SnO2 cassiterite nanoparticles
AU - Spencer, Elinor C.
AU - Ross, Nancy L.
AU - Parker, Stewart F.
AU - Kolesnikov, Alexander I.
AU - Woodfield, Brian F.
AU - Woodfield, Kellie
AU - Rytting, McKay
AU - Boerio-Goates, Juliana
AU - Navrotksy, Alexandra
PY - 2011/11/3
Y1 - 2011/11/3
N2 - Inelastic neutron scattering (INS) data for SnO2 nanoparticles of three different sizes and varying hydration levels are presented. Data were recorded on five nanoparticle samples that had the following compositions: 2 nm SnO2·0.82H2O, 6 nm SnO2·0. 055H2O, 6 nm SnO2·0.095H2O, 20 nm SnO2·0.072H2O, and 20 nm SnO2·0. 092H2O. The isochoric heat capacity and vibrational entropy values at 298 K for the water confined on the surface of these nanoparticles were calculated from the vibrational density of states that were extracted from the INS data. This study has shown that the hydration level of the SnO2 nanoparticles influences the thermodynamic properties of the water layers and, most importantly, that there appears to be a critical size limit for SnO 2 between 2 and 6 nm below which the particle size also affects these properties and above which it does not. These results have been compared with those for isostructural rutile-TiO2 nanoparticles [TiO 2·0.22H2O and TiO2·0.37H 2O], which indicated that water on the surface of TiO2 nanoparticles is more tightly bound and experiences a greater degree of restricted motion with respect to water on the surface of SnO2 nanoparticles. This is believed to be a consequence of the difference in chemical composition, and hence surface properties, of these metal oxide nanoparticles.
AB - Inelastic neutron scattering (INS) data for SnO2 nanoparticles of three different sizes and varying hydration levels are presented. Data were recorded on five nanoparticle samples that had the following compositions: 2 nm SnO2·0.82H2O, 6 nm SnO2·0. 055H2O, 6 nm SnO2·0.095H2O, 20 nm SnO2·0.072H2O, and 20 nm SnO2·0. 092H2O. The isochoric heat capacity and vibrational entropy values at 298 K for the water confined on the surface of these nanoparticles were calculated from the vibrational density of states that were extracted from the INS data. This study has shown that the hydration level of the SnO2 nanoparticles influences the thermodynamic properties of the water layers and, most importantly, that there appears to be a critical size limit for SnO 2 between 2 and 6 nm below which the particle size also affects these properties and above which it does not. These results have been compared with those for isostructural rutile-TiO2 nanoparticles [TiO 2·0.22H2O and TiO2·0.37H 2O], which indicated that water on the surface of TiO2 nanoparticles is more tightly bound and experiences a greater degree of restricted motion with respect to water on the surface of SnO2 nanoparticles. This is believed to be a consequence of the difference in chemical composition, and hence surface properties, of these metal oxide nanoparticles.
UR - http://www.scopus.com/inward/record.url?scp=80055026805&partnerID=8YFLogxK
U2 - 10.1021/jp202518p
DO - 10.1021/jp202518p
M3 - Article
AN - SCOPUS:80055026805
SN - 1932-7447
VL - 115
SP - 21105
EP - 21112
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 43
ER -