Electrochemical Stability of Dual-Atom Catalysts from First Principles

An emerging extension of single-atom catalysts (SACs) is represented by dual-atom catalysts (DACs), in which pairs of metal atoms are embedded within a supporting matrix to form cooperative active sites. Density functional theory (DFT) calculations are widely used to screen candidate structures and identify activity descriptors. However, catalyst design strategies that focus primarily on activity often overlook a critical aspect: stability under operating conditions. General first-principles frameworks to evaluate the stability of SACs in electrochemical environments, explicitly accounting for the effects of pH and applied potential, have been proposed through the construction of Pourbaix diagrams (ACS Catal., 2024, 14, 45). Here, we extend the approach to the much more complex case of DACs. The method relies on thermodynamic cycles whose energetic parameters are obtained from DFT calculations or, when available, experimental data. We validate the approach against experimentally reported N-doped graphene-based DAC systems, which have been successfully synthesized and applied in electrochemical reactions. We then extend the analysis to a series of homonuclear DACs to systematically assess their electrochemical stability. Our investigation provides a rather unexpected result as, although DACs are often expected to outperform their single-atom counterparts in terms of catalytic activity, they generally exhibit lower stability under electrochemical conditions. These findings highlight the importance of explicitly incorporating electrochemical stability into computational catalyst design of DACs. To facilitate its use and diffusion to the community, the simulation code is freely available for straightforward evaluation of the thermodynamic stability of DACs.