Premium
Tuning the Catalytic Selectivity of Copper Using TiO 2 : Water‐Gas Shift versus CO Oxidation
Author(s) -
Kim Hyun You,
Liu Ping
Publication year - 2013
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.201300449
Subject(s) - selectivity , catalysis , dissociation (chemistry) , water gas shift reaction , chemistry , copper , oxide , redox , inorganic chemistry , photochemistry , organic chemistry
As an early attempt to tune the selectivity of Cu catalysts through oxide deposition, we performed DFT calculations to study the water‐gas shift (WGS) and CO oxidation reactions at the interface of Cu(1 1 1) modified by TiO 2 clusters [TiO 2 /Cu(1 1 1)]. Pure Cu catalyzes both reactions, though the overall conversion is hindered by either H 2 O dissociation or O 2 dissociation. Our results show that after depositing TiO 2 , TiO 2 /Cu(1 1 1) promotes the CO oxidation reaction and suppresses the WGS reaction. The active Ti 3f Cu site at the TiO 2 /Cu(1 1 1) interface plays an essential role in tuning the selectivity. During the CO oxidation reaction, the Ti 3f Cu site enables the facile O 2 dissociation at the interface, which leads to the oxidation of the surface layer on Cu(1 1 1) and the formation of Cu 2 O. According to our calculations, the produced TiO 2 /Cu 2 O(1 1 1) interface is active toward CO oxidation, which not only binds O 2 and CO well but also enables a facile OO bond cleavage via the OOCO intermediate. During the WGS reaction, the Ti 3f Cu site is poisoned by CO and the rate‐limiting H 2 O dissociation and therefore the overall WGS is hindered. The results suggest that high selectivity, one of the focuses for next generation catalysts, can be achieved by modifying the chemical properties of the interface.