Phonon Resonance Catalysis in NO Oxidation on Mn-Based Mullite

Abstract

A phonon is the medium a bulk material used to exchange energy with the environment and is thus crucial for heterogeneous catalysis. However, a physical correlation between phonons and catalytic processes has not been established yet. Herein, by combining various in situ characterization techniques, we discovered the intrinsic correlations between phonon modes and the vibrations of reactant intermediates during NO oxidation on the mullite catalyst YMn2O5. It was found that the active phonon modes (350 (Ag(5)) and 670 cm–1 (B1g(12))) are strongly correlated with the vibrational frequencies of the adsorbed −O2 and −O–NO2 intermediates. The resulting resonance will transfer the superposed energy (nℏω) of the high-energy phonons to reactants one by one via the unit energy (ℏω) and then increase the vibrational amplitude along the reaction direction, contributing to the increase in the entropy of the surface reactants and thus the reduction of the Gibbs energy of activation. Phonon resonance catalysis (PRCAT) was thus proposed based on this discovery. This work provides insights into the bidirectional selection of catalysts and precise chemical reactions by matching catalyst phonons with reactant vibrational frequencies