Abstract
In this chapter we discuss the application of inelastic and quasielastic
neutron scattering to the elucidation of the structure, energetics, and
dynamics of water confined on the surfaces of mineral oxide nanoparticles.
We begin by highlighting recent advancements in this active field of research
before providing a brief review of the theory underpinning inelastic
neutron scattering (INS) and quasielastic neutron scattering (QENS) techniques.
We then discuss examples illustrating the use of neutron scattering
methods for studying hydration layers that are an integral part of the
nanoparticle structure. The first investigation of this kind, namely the INS
analysis of hydrated ZrO2 nanoparticles, is described, as well as a later,
complementary QENS study that allowed for the dynamics of diffusion of
the water molecules within the hydration layer to be examined in detail.
The diverse range of information available from INS experiments is illustrated
by a recent study combining INS with calorimetric experiments that
elucidated the thermodynamic properties of adsorbed water on anatase
(TiO2) nanoparticles. To emphasize the importance of molecular dynamics
(MD) simulations for deconvoluting complex QENS spectra, we describe
both the MD and QENS analysis of rutile (TiO2) and cassiterite (SnO2)
nanoparticle systems and show that, when combined, data obtained by
these two complementary methods can provide a complete description of
the motion of the water molecules on the nanoparticle surface. We close
with a glimpse into the future for this thriving field of research.
