Thermodynamics and Kinetics of Ga Surface Segregation in Cu–Ga Nanoparticles across Composition and Particle Size
Year: 2026
Type: preprint
Abstract: Cu–Ga nanoparticles are promising catalysts for thermochemical and electrochemical CO2 conversion, with their catalytic behavior determined by their surface composition. Here, we combine density functional theory (DFT) calculations with machine-learned interatomic potentials (MLIPs) to determine how Ga distributes within Cu–Ga nanoparticles depending on composition, size, and temperature. DFT results show that Ga forms a homogeneous solid solution within the bulk Cu lattice, whereas Ga-rich terminations are favored for surfaces. Molecular dynamics (MD) simulations at the nanosecond scale for particles (within 2 nm to 4.5 nm) and Ga contents up to 24 % reveal progressive Ga migration toward the surface. The extent and rate of this redistribution increase with temperature and Ga content, accompanied by increasing sphericity and structural disorder, until Ga surface enrichment saturates. The surface Ga fraction remains similar across particle sizes, whereas the fraction of total Ga at the surface decreases as particle size increases. A mean-field model captures this surface-to-interior partitioning, reproducing the surface compositions for the MD simulations at high temperatures. At lower temperatures and for larger nanoparticles, Ga redistribution is kinetically limited within the timescale of the simulations. Calculated apparent diffusion barriers for Cu and Ga obtained at high temperatures support this interpretation.
Source: ChemRxiv
Institutions: TU Wien, Ruhr University Bochum
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7222976521