1 research outputs found
Resolving the Oxygen Species on Ozone Activated AgAu Alloy Catalysts for Oxidative Methanol Coupling
Bimetallic alloy catalysts frequently demonstrate distinct
performances
that are superior to their monometallic counterparts, yet their surface
chemistry needs to be carefully studied to understand their structure–activity
relationships. The nanoporous Ag0.03Au0.97 alloy
catalyst becomes highly active and selective for oxidative methanol
coupling to methyl formate after O3 activation. HS-LEIS
reveals the O3 treatment results in enrichment of Ag (>30%)
on the outermost surface layer, while oxygen treatment additionally
leads to segregation of a larger portion of Cu impurity on the surface.
A series of characteristic Raman bands at 395, 577, 867, and 904 cm–1 only form under oxidative methanol coupling reaction
on O3-activated AgAu catalyst. These bands correspond to
Ag3–O* (395 cm–1), M–O*
on O–Au(111) and AgAu alloy (577 cm–1), CH3OH* (867 cm–1), and HOOH* (904 cm–1), as revealed by DFT calculations. The cyclic in situ Raman and reactivity studies indicate the detected oxygen species
could be related to a “memory effect” of the catalyst
upon pretreatment. The current study highlights the importance of
applying surface-specific techniques for investigation of compositions
of outermost surface layers of alloy catalysts, as well as integration
of in situ spectroscopies and computational investigations
for understanding surface structures at the molecular level under
reaction conditions