Equivalent Monolayers Research Articles

Electromagnetic field distribution on a rough gold thin film: An experimental study as a function of the gold thickness

The electromagnetic field distribution on an illuminated rough gold surface has been investigated by apertureless scanning near-field optical microscopy. The sample consists of an alumina substrate with a variable gold coverage ranging from 0 to 30 monolayers (ML). For such small thicknesses, the metal layer is not continuous but exhibits a certain roughness. We have studied the influence of this thickness on the electromagnetic field localization on the surface. For a gold coverage smaller than 10 equivalent monolayers, the electromagnetic field is almost uniform on the surface. For 10 and 14ML, the field becomes inhomogeneous and isolated, localized peaks start to be visible. The width of the peaks is smaller than 50nm. Above 14ML, strong variations are apparent everywhere on the sample. Their amplitude tends to saturate beyond 24ML. A complete statistical study of the sample (standard deviation, Fourier analysis) is performed.

Ultrathin TiOx Films on Pt(111): A LEED, XPS, and STM Investigation

Ultrathin ordered titanium oxide films on Pt(111) surface are prepared by reactive evaporation of Ti in oxygen. By varying the Ti dose and the annealing conditions (i.e., temperature and oxygen pressure), six different long-range ordered phases are obtained. They are characterized by means of low-energy electron diffraction (LEED), X-ray photoemission spectroscopy (XPS), and scanning tunneling microscopy (STM). By careful optimization of the preparative parameters, we find conditions where predominantly single phases of TiO(x), revealing distinct LEED pattern and STM images, are produced. XPS binding energy and photoelectron diffraction (XPD) data indicate that all the phases, except one (the stoichiometric rect-TiO2), are one monolayer thick and composed of a Ti-O bilayer with interfacial Ti. Atomically resolved STM images confirm that these TiO(x) phases wet the Pt surface, in contrast to rect-TiO2. This indicates their interface stabilization. At a low Ti dose (0.4 monolayer equivalents, MLE), an incommensurate kagomé-like low-density phase (k-TiO(x) phase) is observed where hexagons are sharing their vertexes. At a higher Ti dose (0.8 MLE), two denser phases are found, both characterized by a zigzag motif (z- and z'-TiO(x) phases), but with distinct rectangular unit cells. Among them, z'-TiO(x), which is obtained by annealing in ultrahigh vacuum (UHV), shows a larger unit cell. When the postannealing of the 0.8 MLE deposit is carried out at high temperatures and high oxygen partial pressures, the incommensurate nonwetting, fully oxidized rect-TiO2 is found The symmetry and lattice dimensions are almost identical with rect-VO2, observed in the system VO(x)/Pd(111). At a higher coverage (1.2 MLE), two commensurate hexagonal phases are formed, namely the w- [(square root(43) x square root(43)) R 7.6 degrees] and w'-TiO(x) phase [(7 x 7) R 21.8 degrees]. They show wagon-wheel-like structures and have slightly different lattice dimensions. Larger Ti deposits produce TiO2 nanoclusters on top of the different monolayer films, as supported both by XPS and STM data. Besides the formation of TiO(x) surfaces phases, wormlike features are found on the bare parts of the substrate by STM. We suggest that these structures, probably multilayer disordered TiO2, represent growth precursors of the ordered phases. Our results on the different nanostructures are compared with literature data on similar systems, e.g., VO(x)/Pd(111), VO(x)/Rh(111), TiO(x)/Pd(111), TiO(x)/Pt(111), and TiO(x)/Ru(0001). Similar and distinct features are observed in the TiO(x)/Pt(111) case, which may be related to the different chemical natures of the overlayer and of the substrate.

Selective hydrogenation of crotonaldehyde on Pt/ZnCl 2/SiO 2 catalysts

5 wt% Pt deposited on two different supports made of 3 and 1/6 equivalent monolayers of ZnCl 2 deposited on silica (termed Pt30 and Pt2) were prepared and tested in the selective hydrogenation of crotonaldehyde. Pt-based catalysts were prepared starting from tetraammine platinum nitrate as a metallic salt precursor. These catalysts showed very different catalytic behaviors in terms of the activity and the selectivity during time on stream. Pt2 was more active than Pt30 but less selective toward the formation of crotyl alcohol. On the Pt30 catalyst, the selectivity to the formation of crotyl alcohol increased with the reduction temperature, whereas the activity did not change significantly. When the catalyst was reduced at 400 °C, the selectivity to crotyl alcohol was >80%. It behaved similarly to Pt/ZnO catalysts prepared from hexachloroplatinic acid precursor [F. Ammari, J. Lamotte, R. Touroude, J. Catal. 221 (2004) 32]. In contrast, the Pt2 sample showed a decrease in the selectivity to crotyl alcohol and an increase in the activity with increasing reduction temperature. The catalysts were extensively characterized by BET, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and Fourier transform infrared pyridine adsorption. The higher selectivity of Pt30 is explained by a synergetic effect of Zn and chlorine. The greater amount of chlorine present on the catalyst surface led to an increase in the Lewis acidity of the support; moreover, the formation of PtZn alloy was observed. In agreement with our previous findings, we propose that modification of the electronic properties of platinum both from alloying to Zn and from the Lewis acidity of the support changes the adsorption mode of crotonaldehyde by favoring the binding of terminal oxygen of the molecule to the electronically modified platinum atoms.

Growth of Copper on Single Crystalline ZnO: Surface Study of a Model Catalyst

Copper, vapor-deposited on the polar, Zn-terminated ZnO(0001) surface is investigated in view of its suitability as model system for the technologically important Cu/ZnO catalyst. The structure and electronic properties of Cu clusters on ZnO(0001)–Zn have been studied with scanning tunneling microscopy (STM), low energy electron diffraction (LEED), ultraviolet photoelectron spectroscopy (UPS), and low-energy He+ ion scattering (LEIS). At room temperature copper grows as two-dimensional (2D) clusters only at very low coverages of 0.001–0.05 equivalent monolayers (ML). At coverages greater than 0.01 ML, 3D clusters start to develop. This is contrasted to Cu growth on the oxygen-terminated ZnO(0001bar) surface, where a strong adhesion between Cu and the ZnO substrate results in an initial wetting of the surface by Cu. On ZnO(0001)–Zn, surface roughness and sputter damage change the growth mode to more 2D-like. Annealing in UHV results in well-separated, hexagonal clusters rotationally aligned with the substrate. Annealing of 2–5 ML Cu deposits on the ZnO(0001)–Zn surface in 10−6 mbar O2 results in the formation of a (√3 × √3)R30° superstructure with respect to the ZnO lattice. This superstructure likely contains Cu+ sites. The suitability of the different surface morphologies to probe specific sites that are thought to be active for catalytic processes is discussed.

Nucleation and growth of Cu onto polycrystalline Pt electrode from acidic CuSO4 solution in the presence of H2SeO3

The early stages of Cu electrodeposition onto Pt(poly) have been investigated in 0.5 M H2SO4 + 0.01 M CuSO4 solution without or with H2SeO3 when a molar concentration ratio [Cu(II)]/[Se(IV)] ≥ 2×102 using electrochemical and ex situ AFM techniques. The overpotential deposition of Cu has been performed onto a Pt surface precovered independently with Cu in amount close to an equivalent monolayer. Chronoamperometric results have been shown to follow an instantaneous 3D nucleation and diffusion-controlled growth model. The values of diffusion coefficient D for Cu2+, number of nuclei N and average nuclei radius r av have been calculated. In the local regions of the surface, the separate large agglomerates composed of the different diameter clusters have been revealed in both cases, but, in the presence of the H2SeO3, they attained a distinct chain-like configuration. Some morphological characteristics have been reported.

Evaporation of Ni and carbon containing species onto NiO/Ni as case study for metal support catalysts investigated by Metastable Induced Electron Spectroscopy (MIES)

The surface of NiO layers on Ni(1 0 0) has been exposed to Ni vapor in order to evaluate electronically different surface regions on a metal/metal oxide system as model for metal supported catalysts. The adsorption of Ni atoms or else small clusters of Ni atoms has been observed by Metastable Induced Electron Spectroscopy (MIES) as well as XPS and UPS. The spectrum for this situation extracted from a series of MIE spectra excludes the possibility that the adsorbed nickel takes on a metallic character up to one monolayer equivalent of adsorbed nickel. Further, the unexpected presence of a carbon containing compound emanating from the nickel oven leads to the site-specific coverage of the adsorbed nickel by hydrocarbons. Whether we observe the adsorption of hydrocarbons or the formation of hydrocarbons on site cannot be decided on the basis of the present experiment. In any case the ability of MIES to detect site-specific processes without possessing lateral resolution remains noteworthy.

Coverage-dependent dissociation ofH2O on Pd/MgO(100)/Mo(100)

The adsorption of H2O on Pd deposited upon MgO(100) thin films prepared on Mo(100) was studied using low-energyelectron diffraction, ultraviolet photoelectron spectroscopy and high-resolution electronenergy loss spectroscopy. A non-metallic feature of Pd has been observed at the coverage ofPd less than 1.5 monolayer equivalents (MLE) on the MgO(100) films. Partially dissociatedH2O was detected on Pd/MgO(100)/Mo(100), andH2O dissociatesmost readily at ∼0.5 MLE Pd coverage. This coverage-dependent dissociation has arisen from a combinationof the size effect of Pd particles and a vacancy-induced modification of surfacereactivity.

Preparation of gold nanoparticles by heat treatment of sputter deposited gold on boron-doped diamond film electrode

A novel two-step method was developed to synthesize gold nanoparticles on boron-doped diamond (BDD) electrode. It consisted of sputter deposition of maximum 15 equivalent monolayers of gold, followed by a heat treatment at 400–600 °C in air. The as-sputtered gold deposits were highly dispersed (estimated particle size of 2–7 nm) but also unstable, a continuous potential cycling in the stability region of sulfuric acid leading to complete loss of the deposited gold. Subsequent heat treatment of as-sputtered deposits resulted in formation of a stable population of nanosized gold particles characterized by scanning electron microscopy and cyclic voltammetry. Gold nanoparticles with an average size of 15–35 nm could be prepared by this method on polycrystalline BDD film electrode, the particle size being dependent of the deposited amount. The invariant voltammetric response of the heat-treated gold deposits confirmed their applicability for electrocatalysis.

On the determination of surface areas in activated carbons

The paper examines the validity of two approaches frequently used to determine surface areas in activated carbons, namely the BET method and the use of immersion calorimetry. The study is based on 21 well characterized carbons, whose external and microporous surface areas, S e and S mi, have been determined by a variety of independent techniques. It appears clearly that S BET and the real surface area S mi + S e are in agreement only for carbons with average pore widths L o around 0.8–1.1 nm. Beyond, S BET increases rapidly and S BET − S e is practically the monolayer equivalent of the micropore volume W o. This confirms that a characterization of surface properties based on S BET is, a priori, not reliable. The study of the enthalpy of immersion of the carbons into benzene at 293 K, based on Dubinin’s theory, shows that Δ i H consists of three contributions, namely from the interactions with the micropore walls (−0.136 J m −2), the external surface (−0.114 J m −2), and from the volume W o ∗ of liquid found between the surface layers in the micropores (−141 J cm −3). It appears that for carbons where L o > 1 nm, the real surface area cannot be determined in a reliable way from the enthalpy of immersion and a specific heat of wetting alone.

High-Resolution X-ray Photoelectron Spectroscopic Studies of Alkylated Silicon(111) Surfaces

Hydrogen-terminated, chlorine-terminated, and alkyl-terminated crystalline Si(111) surfaces have been characterized using high-resolution, soft X-ray photoelectron spectroscopy from a synchrotron radiation source. The H-terminated Si(111) surface displayed a Si 2p(3/2) peak at a binding energy 0.15 eV higher than the bulk Si 2p(3/2) peak. The integrated area of this shifted peak corresponded to one equivalent monolayer, consistent with the assignment of this peak to surficial Si-H moieties. Chlorinated Si surfaces prepared by exposure of H-terminated Si to PCl5 in chlorobenzene exhibited a Si 2p(3/2) peak at a binding energy of 0.83 eV above the bulk Si peak. This higher-binding-energy peak was assigned to Si-Cl species and had an integrated area corresponding to 0.99 of an equivalent monolayer on the Si(111) surface. Little dichloride and no trichloride Si 2p signals were detected on these surfaces. Silicon(111) surfaces alkylated with CnH(2n+1)- (n = 1 or 2) or C6H5CH2- groups were prepared by exposing the Cl-terminated Si surface to an alkylmagnesium halide reagent. Methyl-terminated Si(111) surfaces prepared in this fashion exhibited a Si 2p(3/2) signal at a binding energy of 0.34 eV above the bulk Si 2p(3/2) peak, with an area corresponding to 0.85 of a Si(111) monolayer. Ethyl- and C6H5CH2-terminated Si(111) surfaces showed no evidence of either residual Cl or oxidized Si and exhibited a Si 2p(3/2) peak approximately 0.20 eV higher in energy than the bulk Si 2p(3/2) peak. This feature had an integrated area of approximately 1 monolayer. This positively shifted Si 2p(3/2) peak is consistent with the presence of Si-C and Si-H surface functionalities on such surfaces. The SXPS data indicate that functionalization by the two-step chlorination/alkylation process proceeds cleanly to produce oxide-free Si surfaces terminated with the chosen alkyl group.

Lithium adsorption on TiO2: studies with electron spectroscopies (MIES and UPS)

The adsorption of lithium atoms on rutile TiO2(110) single crystals was studied with metastable-induced electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy (UPS(HeI)) between 130 K and room temperature. Some auxiliary measurements on W(110) required for data interpretation are also reported. At 130 K ionic adsorption at titania prevails up to 0.3 monolayer equivalents (MLE) as judged from the weak Li(2s) emission in MIES for these exposures. The reduction of the Ti4+ cation is manifested by the growth of an occupied bandgap state in UPS: the alkali s-electron is transferred to a near-surface cation, thereby reducing it to Ti3+ 3d. The transfer of the s-electron is responsible for the observed work function decrease up to ∼0.5 MLE coverage. From the analysis of the UPS Ti3+ 3d signal, as well as from the Li(2s) emission, it is concluded that the degree of ionicity of the adsorbed Li decreases from 100% at 0.3 MLE to 40% at 0.7 MLE. Above 0.5 MLE the MIES spectra are dominated by an Li(2s)-induced peak indicating the presence of Li with an at least partially filled 2s orbital. At temperatures above 160 K this peak is almost absent. Excluding Li desorption at these temperatures, we suggest that Li moves into or below the rutile TiO2(110) surface above 160 K. Lithium insertion into the surface and intercalation are discussed. Copyright © 2004 John Wiley & Sons, Ltd.

Investigation of Surface Structures of Dispersed V2O5 on CeO2−SiO2, CeO2−TiO2, and CeO2−ZrO2 Mixed Oxides by XRD, Raman, and XPS Techniques

The techniques of X-ray diffraction (XRD), Raman spectroscopy (RS), and X-ray photoelectron spectroscopy (XPS) were employed to investigate dispersion and structural characteristics of V2O5/CeO2−MO2 (M = Si4+, Ti4+, and Zr4+) catalysts calcined at different temperatures from 773 to 1073 K. The CeO2−MO2 (1:1 mole ratio) mixed oxides were obtained by soft chemical methods with ultrahigh-dilution solutions, and a nominal monolayer equivalent of V2O5 was deposited over the calcined (773 K) supports. The XRD and RS results suggest that the CeO2−MO2 carrier calcined at 773 K exhibits the presence of nanocrystalline cubic CeO2 on the surface of SiO2 in CeO2−SiO2, CeO2 and TiO2 (anatase) in CeO2−TiO2, and Ce0.75Zr0.25O2 in CeO2−ZrO2 samples. The impregnation of vanadia over CeO2−MO2 and their subsequent calcination at higher temperatures leads to various modifications. The deposited V2O5 is in a highly dispersed state when calcined at 773 K. In particular, no crystalline V2O5 is observed at all calcination temper...

Stabilization of nanosized titania-anatase for high temperature catalytic applications

M 2 O 3 -TiO 2 (M = Ga, In and La) composite oxides were prepared by a co-precipitation method with in situ generated ammonium hydroxide and were impregnated with 12 wt.% V 2 O 5 . The M 2 O 3 -TiO 2 and V 2 O 5 /M 2 O 3 -TiO 2 (M = Ga, In and La) samples were subjected to thermal treatments from 773 to 1073 K and were investigated by X-ray diffraction, FT-infrared, and BET surface area methods to establish the effects of vanadia loading and thermal treatments on the surface structure of the dispersed vanadium oxide species and temperature stability of these catalysts. Characterization results suggest that the co-precipitated M 2 O 3 -TiO 2 composite oxides are in X-ray amorphous state and exhibit reasonably high specific surface area at 773 K calcination. The M 2 O 3 -TiO 2 mixed oxide supports also accommodate a monolayer equivalent of V 2 O 5 (12 wt.%) in a highly dispersed state. The V 2 O 5 /M 2 O 3 -TiO 2 catalysts are thermally stable up to 873-973 K calcination temperature. When subjected to thermal treatments beyond 873-973 K, the dispersed vanadium oxide selectively interacts with In 2 O 3 or La 2 O 3 portions of the respective mixed oxides and forms InVO 4 or LaVO 4 compounds. The remaining TiO 2 appears in the form of anatase or rutile phase. In the case of V 2 O 5 /Ga 2 O 3 -TiO 2 sample, no such surface vanadate compound formation was observed. All samples were evaluated for one step synthesis of 2,6-dimethylphenol from cyclohexanone and methanol mixtures in the vapour phase at normal atmospheric pressure. The 12% V 2 O 5 /La 2 O 3 -TiO 2 catalyst exhibited good conversion and product selectivity among various samples investigated.

Reactive deposition of NiO ultrathin films on Pd(1 0 0)

NiO ultrathin films have been grown on Pd(1 0 0) following a reactive deposition procedure. Ni has been dosed at room temperature on the substrate surface in an oxygen partial pressure of 4 × 10 −6 mbar. The electronic and structural evolution of the resulting NiO(1 0 0) ultrathin films has been followed by means of X-ray photoelectron spectroscopy (XPS), X-ray photoelectron diffraction (XPD), low energy electron diffraction (LEED), and scanning tunnelling microscopy (STM). XPS, XPD and STM data indicate a 2D growth of the first NiO monolayer, while further growth leads to the nucleation of 3D islands, in a Stranski–Krastanov growth scheme. Combined XPD and LEED data indicate an initially pseudomorphic growth, characterised by in-plane compressive tetragonal strain of the NiO film, with a consequent out-of-plane interlayer expansion. Partial strain relaxation occurs abruptly, very likely between the second and the third atomic layer of the 3D islands, while a completely bulk-like cubic environment is reached only gradually as a function of thickness. NiO(1 0 0) films even ∼50 equivalent monolayers thick can be grown with good long-range order, as shown by (1 × 1) LEED images.

Grain boundary saturation and grain growth

In nanoscale alloys with strong segregation tendency, the grain size at metastable thermodynamic equilibrium is determined by the grain boundary energy, the enthalpy change of grain boundary segregation, and the solute excess of an equivalent grain boundary monolayer at saturation. Good agreement between experiment and thermodynamic description has been found with respect to the temperature-dependence of the metastable grain size.

Angle resolved X-ray photoelectron spectroscopy study of Au deposited on Pt and Re surfaces

Abstract The growth of Au on Pt and Re sputtered and annealed surfaces was investigated by angle resolved XPS method. The shifts of Au 4f core electron binding energy were negative for Au deposited on Pt and higher in magnitude than positive shifts observed for Au on Re. The shifts did not depend on the structure of the Pt substrate surface but were affected by structure of the Re surface. More than 5 equivalent monolayers of Au on Pt were required to obtain bulk-like spectra while 2 monolayers were sufficient for Au/Re. The results suggested formation of several monolayers thick interface Au–Pt alloy in contrast to abrupt Au/Re interface. The measured trends in Au 4f core level shifts were reproduced by those calculated using local density functional method within the initial state approximation.

Surface and Solution Behavior of the Mixed Dialkyl Chain Cationic and Nonionic Surfactants

The surface and solution behavior of the mixed dialkyl chain cationic and nonionic surfactant mixture of dihexadecyldimethylammonium bromide, DHDAB, and hexaethylene monododecyl ether, C12E6, has been investigated, using primarily the scattering techniques of small-angle neutron scattering and neutron reflectivity. Within the time scale of the measurements, the adsorption of the pure component C12E6 at the air-solution interface shows no time dependence. In contrast, the adsorption of the DHDAB/C12E6 mixture and pure DHDAB has a pronounced time dependence. The characteristic time for adsorption varies with surfactant concentration, composition, and temperature. It is approximately 2-3 h for the DHDAB/C12E6 mixture, dependent upon concentration and composition, and approximately 50 min for DHDAB. At the air-solution interface, the equilibrium composition of the adsorbed layer shows a marked departure from ideal mixing, which is dependent upon both the solution concentration and the concentration of added electrolyte. In contrast, the composition of the aggregates in the bulk solution that are in equilibrium with the surface is close to ideal mixing, as expected for solution concentrations well in excess of the critical micellar concentration. The structure of the mixed adsorbed layer has been measured and compared with the structure of the equivalent pure surfactant monolayer, and no substantial changes in structure or conformation are observed. The extreme departure from ideal mixing in the adsorption behavior of the DHDAB/C12E6 mixture is discussed in the context of the structure of the adsorbed layer, changes in the underlying solution structures, and the failure of regular solution theory to predict such behavior.

Effect of the Mo atom flow on the molybdenum growth on TiO2 (1 1 0) surface

Molybdenum has been deposited at room temperature on stoichiometric TiO2 (110) surfaces with two deposition rates: 0.1 equivalent monolayer (eqML) and 1.5eqMLmin−1. X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy studies clearly reveal an effect of the deposition rate upon the growth mode and the interfacial reaction. Indeed, whereas a strong interfacial reaction between Mo and TiO2 involves a Stranski–Krastanov growth mode with the formation of amorphous molybdenum oxide monolayers for the lowest deposition rate, no reaction can be observed for the highest deposition rate. Moreover in this latter case, the growth mode seems to be a 3D one. These differences are discussed from a pure kinetics point of view.

Growth of NiO ultrathin films on Pd(1 0 0) by post-oxidation of Ni films: the effect of pre-adsorbed oxygen

This paper reports on the optimisation of the growth parameters of NiO ultrathin films on Pd(1 0 0). Growth is performed by means of UHV metal deposition and post-oxidation cycles. Chemical and structural characterisation of the deposits is achieved by means of electron spectroscopy (X-ray photoelectron spectroscopy, XPS; angle resolved XPS) and electron diffraction techniques (low energy electron diffraction, LEED; X-ray photoelectron diffraction, XPD). Three growth procedures have been investigated, which differ for the particular growth parameters adopted in each case. We demonstrate that post-oxidation is effective in order to obtain epitaxial NiO only if the initial dose of Ni evaporated on the clean Pd(1 0 0) substrate exceeds a critical value, corresponding approximately to two equivalent monolayers. However, the overlayer thus obtained is strongly understoichiometric in oxygen close to the metal/oxide interface and poorly ordered on the long range. When a Ni dose below this limiting first value is used, the layer evolves toward polycrystalline NiO, due to substantial oxidation of the Pd substrate promoted by the presence of Ni, very likely through a work function decrease upon direct metal/metal interface formation. On the contrary, epitaxial NiO(1 0 0) layers of good structural quality, with limited oxygen deficiency at the interface, with negligible substrate oxidation and with a good degree of long-range order are obtained if deposition and post-oxidation cycles are initiated on an oxygen pre-saturated Pd surface, characterised by the (√5×√5)- R27° O/Pd(1 0 0) LEED pattern. We therefore demonstrate that oxygen can act either as an inhibitor or as a promoter of NiO epitaxial growth on Pd(1 0 0), depending on the way it is used.

Preparation and characterization of In 2O 3-TiO 2 and V 2O 5/In 2O 3-TiO 2 composite oxides for catalytic applications

In 2O 3-TiO 2 (1:13 mole ratio) mixed oxide was prepared by a co-precipitation method with in situ generated ammonium hydroxide and was impregnated with various amounts of V 2O 5 (4–12 wt.%). The In 2O 3-TiO 2 and V 2O 5/In 2O 3-TiO 2 samples were subjected to thermal treatments from 773 to 1073 K and were investigated by X-ray diffraction, FT-infrared, and BET surface area methods to establish the effects of vanadia loading and thermal treatments on the surface structure of the dispersed vanadium oxide species and temperature stability of these catalysts. Characterization results suggest that the co-precipitated In 2O 3-TiO 2 is in X-ray amorphous state and exhibits reasonably high specific surface area. The In 2O 3-TiO 2 also accommodates a monolayer equivalent of V 2O 5 (12 wt.%) in a highly dispersed state. The V 2O 5/In 2O 3-TiO 2 catalyst is thermally stable up to 873 K calcination temperature. When subjected to thermal treatments beyond 873 K, the dispersed vanadium oxide selectively interacts with In 2O 3 portion of the mixed oxide and forms InVO 4 compound. The remaining TiO 2 appears in the form of anatase or rutile phase. These samples were evaluated for one step synthesis of 2,6-dimethylphenol from cyclohexanone and methanol mixtures in the vapour phase at normal atmospheric pressure. The 12% V 2O 5/In 2O 3-TiO 2 catalyst exhibits good conversion and product selectivity among various samples investigated.