Stabilising gallium-based liquid metal alloy nanoparticles by carbon encapsulation

Gallium-based liquid metal (LM) nanoparticles hold an exceptional promise for catalysis, energy storage, and printed electronics due to their high conductivity, fluidity, and dynamic catalytic surfaces. However, maintaining their mechanical and chemical stability remains a major challenge, as LM nanoparticles tend to agglomerate due to their high surface tension and are susceptible to chemical degradation, such as dissolution or leaching in reactive environments. Surface modification and encapsulation techniques are employed to enhance the mechanical and functional stability of these particles. Previously, methane pyrolysis has been considered as a route to produce high-purity hydrogen and carbon. In this work, we employ methane pyrolysis as a controllable route to synthesise carbon-encapsulated Ga-based alloy nanoparticles (NPs), where catalytic activity serves as the driving mechanism for shell formation rather than the ultimate function of the material. During pyrolysis, trimetallic Cu–Pt–Ga NPs act as transient catalytic sites that initiate carbon growth, while the resulting graphitic shell provides mechanical confinement, prevents agglomeration, and enhances resistance to leaching. By tuning alloy composition, the rate and morphology of carbon formation can be modulated, enabling precise control over the resulting core–shell architecture. Overall, the primary contribution of this work is the demonstration of a robust and general method for producing carbon-coated liquid-metal nanomaterials with tailored structural and functional properties for applications beyond catalysis.