As before, in this simulated search the approach guided by ML predictions is many times faster than searching randomly, despite the added complexity of predicting a property dependent on multiple intermediates. The speedup ratio is smaller to the degree expected given the increase from 15 to 50 catalysts in the search space. We made this change because when we initially considered a search space of the top 15 catalysts, the classification method trained only on structural features did not correctly identify a single active site from that set, indicating that the catalysts with the highest predicted overpotential, which are not the same as the ones that bind O2 most strongly, are much harder to classify as active based on structural features alone.