TiO2-mediated

The Genesis and Principle of Catalysis at Oxide Surfaces Surface-Mediated Dynamic Aspects of Catalytic Dehydration and Dehydrogenation on TiO2(110) by STM and DFT 317... 

The main effect not considered in the discussion by Lopez et a/.188 is the relative role of support-mediated reactions in the activity of Au clusters. This point of view is quite reasonable, for the aim of the paper by Lopez et al. was to focus on effects that occur across a wide range of supports. Nevertheless, it is interesting to note that most of the reaction pathways that have been specifically identified to date by DFT calculations for CO oxidation on supported gold invoke species that are adsorbed on the support or on the support/cluster interface.167,171,172,185,186 Only the work of Sanchez et al. for Aug on MgO(lOO)166 and calculations of Remediakis et al. for Au10 on reduced TiO2(110)187 have demonstrated a CO oxidation pathway that involves only adsorbates in contact with the Au cluster. In both of these cases, competing pathways that involve the support/cluster interface were also observed. 

Photocatalytic degradation of 4-chlorophenol in TiOz aqueous suspensions produces 4-chlorocatechol, an ortho hydroxylated product, as the main intermediate. This result disagrees with data reported by other researchers, who proposed the formation of a para-hydroxylated product, hydroquinone, as the major intermediate. Results also indicated that further oxidation of 4-chlorocatechol yields hydroxy hydroquinone, which can readily be oxidized and mineralized to carbon dioxide. Complete dechlorination and mineralization of 4-chlorophenol can be achieved. In contrast, direct photolysis of 4-chlorophenol produces hydroquinone and p-benzoquinorie as the main reaction products. The photocatalytic oxidation reaction, initially mediated by TiO2, is generated by an electrophilic reaction of the hydroxyl radical attacking the benzene ring. 

Henderson, MA. Evidence for bicarbonate formation on vacuum annealed TiO2(H0) resulting from a precursor-mediated interaction between CO2 and H2O. Surface Science, 1998, 400, 203-219. 

Kim SH, Stair PC, Weitz E (1999) Substrate-mediated photodesorption fimn multilayers of CH3I on TiO2(110) at 90 K. Chem Phys Lett 302 511-516... 

Bikondoa O, Pang CL, Ithnin R et al (2006) Direct visualization of defect-mediated dissociation of water on TiO2(110). Nat Mater 5 189-192... 

Petrik NG, Kimmel GA (2011) Electron- and hole-mediated reactions in UV-irradiated O2 adsorbed on reduced rutile TiO2(110). J Phys Chem C 115 152-164... 

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