Fig. 5: Energy profile of HMFCA to FFCA oxidation.

a, Adsorption energy profiles extracted from NEB calculations describing the various steps involved in the RDS of HMF oxidation, that is, HMFCA oxidation to FFCA, in the presence of molecular oxygen and TiO2–RuPt. b, The corresponding structures for each predicted step, with the TS highlighted in red. All energy values are relative to the initial state with the HMFCA molecule in the gas phase and a relaxed TiO2–Ru7upPt7 catalyst with two adsorbed oxygen atoms.