Predicting the Stability and Loading for Electrochemical Preparation of Single-Atom Catalysts

Underpotential electrochemical deposition is a convenient approach for precisely controlling the fabrication process of single-atom catalysts (SACs). In achieving a balance between raising the loading of SACs and suppressing the aggregation of the adsorbates, the working electrode potential should be deliberately optimized, for which the adsorption isotherm of the loading of atomically dispersed adsorbates versus electric potential is of crucial importance in performance tuning. We report an integrated theoretical scheme for simulating the adsorption isotherm, which can enormously accelerate the evaluation of the adsorption energy for large model systems by combining our recently proposed constant-potential calculation scheme with the cluster expansion (CE) model, as well as accurately estimate the configurational effect through a thermodynamic integration (TI) computation based on Monte Carlo (MC) simulations. With the established simulation scheme, the surface map of the adsorption free energy as a function of deposition coverage and electric potential is computed for atomically dispersed copper on 1T '-MoS2, which is further employed to reasonably estimate the equilibrium coverage of the deposit at varying electric potentials and predict the feature of the adsorbate distribution pattern, as well as simulate the cyclic voltammogram (CV). Besides, based on the study of nine metal/transition-metal dichalcogenide (TMD) systems, we demonstrate that the well-characterized potential-related metal-substrate and metal-metal interactions provide rational criteria for evaluating the stability of SACs against aggregation under electrochemical conditions.