March 26, 2024
Research Highlight

Uncovering How Interfacial Water Structure Can Stabilize Nanoparticle Dispersion

Interactions between solvent molecules and specific nanoparticle faces can lead to the formation of stable dispersions

Close up of hematite

To investigate how stable nanoparticle suspensions form, researchers used facet engineering on hematite nanoparticles. Results indicated that the stability of nanoparticle suspensions can be controlled through morphology.

The Science

The stability of nanoparticle suspensions is governed by a complex mixture of factors. Avoiding aggregation over time often involves modifying the surface of particles, which can affect the overall properties of the system. Researchers explored differences in the behavior of hematite nanoparticles with different facets exposed to water. They found that (104) hematite nanoparticles were highly stable and remained dispersed across multiple solution conditions, in contrast to (001) and (116) hematite. Calculations showed that water forms a tightly bound layer on the (104) surface, favoring particle dispersion over aggregation.

The Impact

Nanoparticle applications often rely on their high surface area to volume ratio. This requires that a large portion of the nanoparticle surface area remain accessible in solution, a challenge that usually requires surface modification to maintain particle stability and dispersity over time. This work demonstrates that controlling the faceting of nanoparticles can be an effective way to maintain particle dispersity without the introduction of surface modifying additives. 


Nanoparticle aggregation in solution controls both surface reactivity and the overall function of the materials. Complete dispersion usually requires adding sorbents that impart a net repulsive interaction between particles. Facet engineering offers an alternative approach to producing monodisperse suspensions simply based on facet-specific interactions with the solvent molecules. Researchers measured the dispersion/aggregation of three morphologies of hematite (α-Fe2O3) nanoparticles in water using ex situ electron microscopy and in situ small-angle x-ray scattering. The results showed a unique tendency of (104) hematite nanoparticles to maintain a monodisperse state across a wide range of solution conditions not observed in similarly sized (001)- and (116)-dominated particles. Density functional theory calculations reveal an inert, densely hydrogen-bonded first water layer on the (104) facet that favors interparticle dispersion. These data validate the notion that nanoparticle dispersions can be controlled through morphology for specific solvents, which may help in nanoparticle applications that rely on having highly accessible interfacial area in stable suspensions.



Kevin Rosso, Pacific Northwest National Laboratory,

Xin Zhang, Pacific Northwest National Laboratory,


This material is based upon work supported by the Department of Energy (DOE), Office of Science, Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division through its Geosciences Program at Pacific Northwest National Laboratory (PNNL) (FWP# 56674). Part of the research was performed at the Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science user facility at PNNL sponsored by the Biological and Environmental Research program. This work used resources of the Advanced Photon Source, a DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract DE-AC02-06CH11357. Small-angle X-ray scattering data were collected at beamline 12-ID-C under General User Proposals 68517. Simulations were performed using PNNL Institutional Computing resources and the National Energy Research Scientific Computing Center supported by the Office of Science of the DOE operating under contract no. DE-AC02-05CH11231. This work benefited from the use of the SasView application, originally developed under NSF award DMR-0520547. SasView also contains code developed with funding from the EU Horizon 2020 programmed under the SINE2020 project grant no. 654000.

Published: March 26, 2024

Zhou J., Song D., Mergelsberg S., Wang Y., Adhikari N., Lahiri N., Zhao Y., Chen P., Wang Z., Zhang X., Rosso K. M. “Facet-dependent dispersion and aggregation of aqueous hematite nanoparticles,” Sci. Adv., (2024). [DOI: 10.1126/sciadv.adi7494]