Figure 4. Reaction networks for the CO+H₂ reaction on Rh(1 1 1) under DFT uncertainty provided by the BEEF-vdW functional.

(a) All reactions considered for C1 and CCO/OCCO chemistry on Rh(1 1 1). (b) Pathway with the lowest expected limiting transition-state energy, yielding acetaldehyde as a final product. (c) Including less likely reactions in the final mechanism increases the probability that the final network contains the actual rate-limiting step. (d) Reduced mechanism at the 80% confidence level, showing selectivity problems to water and CO₂. (e) Reduced mechanism at the 90% confidence level, suggesting methanol cannot be ruled out as a final product at this confidence level given DFT-level uncertainty.