TY - JOUR
T1 - Strongly Bound Surface Water Affects the Shape Evolution of Cerium Oxide Nanoparticles
AU - Symington, Adam
AU - Molinari, Marco
AU - Moxon, Samuel
AU - Flitcroft, Joseph
AU - Sayle, Dean C.
AU - Parker, Stephen Charles
PY - 2020/2/13
Y1 - 2020/2/13
N2 - The surface structure and composition of functional materials are well-known to be critically important factors controlling the surface reactivity. However, when doped the surface composition will change, and the challenge is to identify its impact on important surface processes and nanoparticle morphologies. We have begun to address this by using a combination of density functional theory and potential-based methods to investigate the effect of surface dopants on water adsorption and morphology of the technologically important material, CeO2, which finds application as electrolyte in SOFCs, catalyst in soot combustion, and enzyme mimetic agents in biomedicine. We show that by mapping CeO2 surface phase diagrams we can predict nanoparticle morphologies as a function of dopant, temperature, and water partial pressure. Our results show that low-temperature, undoped CeO2 nanocubes with active {100} surface sites are thermodynamically stable, but at the typical high temperature, operating conditions favor polyhedra where {100} surfaces are replaced by less active {111} surfaces by surface ion migration. However, doping with trivalent cations, such as Gd3+, will increase binding of water on the {100} surfaces and hence act to preserve the cuboidal architecture by capping the active surfaces. As surfaces tend to be decorated by impurities and dopants it is clear that their role should receive more attention and the approach we describe can be routinely applied to nanomaterials, morphologies, and associated active/inactive surfaces.
AB - The surface structure and composition of functional materials are well-known to be critically important factors controlling the surface reactivity. However, when doped the surface composition will change, and the challenge is to identify its impact on important surface processes and nanoparticle morphologies. We have begun to address this by using a combination of density functional theory and potential-based methods to investigate the effect of surface dopants on water adsorption and morphology of the technologically important material, CeO2, which finds application as electrolyte in SOFCs, catalyst in soot combustion, and enzyme mimetic agents in biomedicine. We show that by mapping CeO2 surface phase diagrams we can predict nanoparticle morphologies as a function of dopant, temperature, and water partial pressure. Our results show that low-temperature, undoped CeO2 nanocubes with active {100} surface sites are thermodynamically stable, but at the typical high temperature, operating conditions favor polyhedra where {100} surfaces are replaced by less active {111} surfaces by surface ion migration. However, doping with trivalent cations, such as Gd3+, will increase binding of water on the {100} surfaces and hence act to preserve the cuboidal architecture by capping the active surfaces. As surfaces tend to be decorated by impurities and dopants it is clear that their role should receive more attention and the approach we describe can be routinely applied to nanomaterials, morphologies, and associated active/inactive surfaces.
KW - Impurities
KW - Oxides
KW - Adsorption
KW - Nanoparticles
KW - Surface energy
U2 - 10.1021/acs.jpcc.9b09046
DO - 10.1021/acs.jpcc.9b09046
M3 - Article
VL - 124
SP - 3577
EP - 3588
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 6
ER -