A single physical descriptor cannot capture the dynamics of such a complex process as in situ nanoparticle formation and catalysis, and uncertainty in the physical process makes it difficult to predict the outcome of individual trials directly without fine control of process conditions. Accurate and comprehensive models of nanoparticle formation, growth, or surface expression remain elusive, and current works typically use experimental characterization techniques to model small numbers of systems in detail , although some multisystem screening tools have been developed recently . Experimental binding energies also often differ significantly from theoretical values, which are generally calculated using DFT over low-index intermetallic surfaces. Such complications include coverage effects , surface poisoning and passivation , transport limitations , and surface strain . The HER over a platinum surface, one of the fastest chemical reactions ever observed, appears to progress through a weak-binding adsorbed intermediate . However, other sources argue that in spite of these factors, the Sabatier principle can be used as a heuristic to guide experimenters toward a subset of materials with the potential for activity . With a view to this controversy, we observe that the most experimentally active chemical systems in our data contain materials with surfaces whose low-coverage binding energies are at or slightly stronger than Then, hydrogen adsorption energy predictions are made for enumerated sites, and the lowest value is taken for every surface on each crystal (two representative surfaces chosen). The surface closest to -0.24 eV is used to represent the chemical system on the x-axis of the volcano plot (bottom right).