The rational design of heterogenous electrocatalysts requires a detailed understanding of the physicochemical properties of catalytic surfaces under applied voltage and in contact with a liquid electrolyte. Significant progress has been made recently in part to refined synthetic approaches that provide an unprecedented level of control over the surface chemistry of catalytic electrodes. One such strategy involves the underpotential deposition of a sacrificial component such as copper followed by a surface limited redox replacement reaction with a nobler component such as platinum. These approaches have enabled the design of cost effective core-shell nanostructures with ultrathin films that often exhibit higher performance and higher durability compared to traditional elemental electrocatalysts. Nevertheless, the efficacy of these electrocatalysts for particular reactions can only be determined after performing detailed experimental studies aimed at measuring the activity, selectivity, and durability of the catalyst under a wide range of experimental conditions. In principle, this process can be accelerated by performing virtual experiments on a computer that can reveal the thermodynamic properties of catalytic electrodes in electrochemical environments. The latter relies heavily on the development of predictive models that are capable of describing the complex nature of the electrode-solution interface in an efficient and effective manner. Recently, we have reported a first principles model of electrodeposition phenomena [Weitzner, S. E. and Dabo, I. npj Computational Materials, in press] that incorporates a polarizable continuum dielectric region and a model ionic countercharge to efficiently describe the liquid electrolyte within density-functional calculations of the interface. Electrification of the quantum–continuum interface enables a direct assessment of the stability of electrodeposited species in electrochemical environments. In this talk, we present recent progress on the modeling of underpotential deposition phenomena and surface limited redox replacement reactions under realistic environmental conditions. We additionally discuss the performance of the interfacial model in describing the stability of bimetallic and trimetallic core-shell nanoparticles for catalysis applications.