Figure 3.

Computed reaction pathways for the overoxidation of formaldehyde. (a) Intermediate structures on the Au(221) surface. Letters next to chemical names indicate different coadsorption states of CH₂O, OCH₂O, OCHO, and CO₂. The infinity symbol designates the limit of low coverage (= no coadsorbates). (b and c) Reaction energy diagrams via OCH₂O (b) and HCOO toward CO₂ (c) for atomic oxygen as the oxidant on flat Au(111) (blue) and stepped Au(221) (orange) as well as for short (O–Au–O, green) and long (O–Au–O–Au–O, red) Au–O chains as oxidants on Au(221).