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Different effects of water molecules on CO oxidation with different reaction mechanisms.

Shan Ping LiuMing ZhaoGuo En SunCanglang YaoQing Jiang
Published in: Physical chemistry chemical physics : PCCP (2018)
The effects of water molecules (promotion/prohibition) on CO oxidation remain debated. Herein, using density functional theory calculations, we demonstrate that water molecules can facilitate the CO + O/O2 oxidation process, but prohibit the CO + OH oxidation process, which is consistent with the experimental finding that water molecules have two distinct effects on CO oxidation. For the CO + O/O2 oxidation mechanisms, we find that the reactants were pushed towards each other due to the steric effect of the water molecules, which decreases the reaction barriers and promotes the CO + O/O2 oxidation process. For the CO + OH oxidation mechanisms, water molecules increase the stability of the COOH* intermeditae by H-bonds and van der Waals forces, which increase the barriers of the COOH* transformation process and the COOH*-tra dissociation process, and prohibit the CO + OH oxidation process. These results clarify the different effects of water molecules on CO oxidation and shed light on catalyst usage in the CO oxidation industry.
Keyphrases
  • hydrogen peroxide
  • electron transfer
  • density functional theory
  • visible light
  • nitric oxide
  • gold nanoparticles
  • molecular dynamics simulations