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Proof of Equivalent Catalytic Functionality upon Photon‐Induced and Thermal Activation of Supported Isolated Vanadia Species in Methanol Oxidation
Author(s) -
Kortewille Bianca,
Wachs Israel E.,
Cibura Niklas,
Pfingsten Oliver,
Bacher Gerd,
Muhler Martin,
Strunk Jennifer
Publication year - 2018
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201800311
Subject(s) - catalysis , photocatalysis , formaldehyde , methanol , photochemistry , chemistry , valence (chemistry) , thermal desorption , homo/lumo , electrochemistry , redox , reaction rate , desorption , inorganic chemistry , chemical engineering , adsorption , organic chemistry , molecule , electrode , engineering
Abstract In this study, evidence is provided that isolated surface vanadia (VO 4 ) species on SiO 2 can similarly act as a thermal heterogeneous catalyst and as a heterogeneous photocatalyst. Structurally identical surface VO 4 species catalyze the selective oxidation of methanol both by thermal activation and by UV‐light induction. Selectivity to formaldehyde appears to be unity. For the photocatalytic reaction at room temperature, formaldehyde desorption is rate limiting. With larger agglomerates or V 2 O 5 nanoparticles, on the contrary, only the thermal reaction is feasible. This is tentatively attributed to the different positions of electronic states (HOMO/LUMO, valence/conduction band) on the electrochemical energy scale owing to the quantum size effect. Besides providing new fundamental insight into the mode of action of nanosized photocatalysts, our results demonstrate that tuning the photocatalytic reactivity of supported transition‐metal oxides by adjusting the degree of agglomeration is feasible.