Sputter Deposition of Nanoparticles in Ionic Liquids

Sputter deposition in ionic liquids represents a versatile physical vapour technique for the synthesis of colloidal nanoparticles free of chemical contaminants and stabilising ligands. In this approach, a metal target is eroded by ion bombardment under vacuum, and the sputtered atoms enter the ionic liquid, where they nucleate and grow into particles. The unique properties of ionic liquids—negligible vapour pressure, wide electrochemical window, tunable viscosity and surface tension—enable fine control over nucleation kinetics, particle size distribution and composition. Parameters such as sputter power, working gas pressure, deposition time, liquid composition and temperature govern the rate of atom arrival at the liquid interface, diffusional motion within the medium and subsequent aggregative growth or agglomeration. Variants of the technique, including high-power impulse magnetron sputtering (HiPIMS), provide additional control by delivering high-energy pulses that can influence crystallinity and morphology in situ. Applications span electrocatalysis, energy-conversion devices, sensing and photonics, where the absence of organic capping agents yields clean particle surfaces and enhanced interfacial activity. Ongoing challenges include elucidation of the detailed formation mechanism, scaling up for industrial production, and expanding the range of multi-metallic and alloy compositions accessible via combinatorial sputtering onto ionic liquid substrates.

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Sputter Deposition of Nanoparticles in Ionic Liquids publication trend

The graph below shows the total number of articles in sputter deposition of nanoparticles in ionic liquids across all publications each year (not limited to Nature Index journals).

Technical terms

Magnetron sputtering: A plasma-based physical vapour deposition method in which a magnetically confined plasma ejects atoms from a solid target.

Ionic liquid: A salt in the liquid state at room temperature, characterised by low volatility and high ionic conductivity, often used as a solvent or stabiliser.

High-power impulse magnetron sputtering (HiPIMS): A pulsed sputtering technique delivering high peak power to improve ionisation and control over film or nanoparticle properties.

Colloidal dispersion: A stable suspension of fine particles or droplets within a continuous medium, preventing rapid sedimentation or aggregation.

Capping agent: A molecule or ion that binds to nanoparticle surfaces to prevent uncontrolled growth or aggregation; absent in pure sputter-deposition methods.

References

1. Sputtering onto liquids: a critical review. Beilstein Journal of Nanotechnology (2022).
2. On the Effects of Diluted and Mixed Ionic Liquids as Liquid Substrates for the Sputter Synthesis of Nanoparticles. Nanomaterials (2020).
3. Controlling the Amorphous and Crystalline State of Multinary Alloy Nanoparticles in An Ionic Liquid. Nanomaterials (2018).