The water-gas shift reaction (WGSR) is an intermediate reaction in hydrocarbon reforming processes, considered one of the most important reactions for hydrogen production, requiring efficient and stable catalysts. Bimetallic nanoparticles such as Cu–Au offer promising tunable reactivity, driven by the balance of their individual properties . In this contribution, we use density functional theory (DFT) to investigate the surface stability of Cu–Au alloys across various ratios and predict nanoparticle shapes as a basis to assess catalytic activity. Thus, we optimized Cu, Au, CuAu (L1₀), Cu₃Au (L1₂), and CuAu₃ (L1₂) bulk phases and constructed slab models to evaluate their stability via surface energy calculations using the PBE and PBE-D3 functionals. The particle prediction shape was evaluated via the Wulff construction highlights the (111) facet as most relevant. On CuAu(111) and Cu3Au(111), we identified the preferred adsorption sites of key WGS reaction intermediates. Using the machine-learning nudged elastic band (ML-NEB) method, we also obtained the key energy barriers to obtain the energy profiles for the direct (redox) and associative (COOH) pathways, comparing the two alloy compositions. DFT gives step-level energetics, but predicting catalyst performance under working conditions, where multiple routes compete and coverages evolve, requires microkinetic modeling to connect energetics to rates and selectivity . Thus, we are building a kinetic Monte Carlo (KMC) model using the DFT energetics to compute turnover frequencies (TOFs) as functions of temperature and reactant partial pressures, and to identify the rate-limiting steps. In parallel, we are modeling Ar⁺ ion beam modification of Cu–Au nanoparticles to simulate beam effects and examine how it reshapes active-site distributions to know how it could impact its catalytic performance. This study evaluates the thermodynamic stability of the main Cu–Au facets and the energetics of the main WGS pathways for both Cu3Au and CuAu, providing the basis to subsequently understand and tune the performance of these materials towards the WGSR.