Supported Transition Metal Oxides Research Articles

Elusive supported surface M2Ox dimer active site (M = Re, W, Mo, Cr, V, Nb, and Ta)

Supported transition metal oxide catalysts are extensively used as heterogeneous catalysts for various energy, chemical, and environmental applications. The molecular structures of dehydrated surface metal oxide phases are crucial for understanding structure-activity/selectivity relationships that guide the design of enhanced catalysts. Some early studies suggested that dimeric (aka binuclear) surface metal oxide sites were more active/selective than monomeric (aka mononuclear) sites, prompting interest in synthesizing catalysts with supported dimeric metal oxide structures. This review examines the literature on dehydrated silica-based supported group 7-5 MOx catalysts (ReOx, WOx, MoOx, CrOx, VOx, NbOx, and TaOx on SiO2, MCM-41, AlOx/SiO2, and H-ZSM-5) for their surface metal oxide structures. In situ Raman, extended x-ray absorption fine structure, and ultraviolet-visible spectroscopy indicate that monomeric surface MOx structures predominate in all such catalysts. Therefore, the cursory use of dimeric surface M2Ox sites in catalytic mechanisms and reaction models in heterogeneous catalysis by supported metal oxides is questionable, and moving forward, the invoking of supporting dimeric surface M2Ox sites should be critically examined and backed up with direct spectroscopic methods.

Conversion of 5‐Hydroxymethylfurfural and Carbohydrates to 2,5‐Diformylfuran Over MoOx/Biochar Catalysts

AbstractHere, a series of nitrogen‐doped carbon (NC) supported transition metal oxide catalysts were prepared by pyrolysis of chitosan‐metal salt mixtures for the efficient synthesis 2,5‐diformylfuran (DFF) from 5‐hydroxymethylfurfural (HMF) and fructose. Among them, supported molybdenum‐based species on nitrogen‐doped carbon (Mo/NC) exhibited excellent activity and selectivity for selective oxidation of HMF to DFF. The presence of nitrogen species reduces the electron cloud density around the Mo species, thereby improving the catalytic activity. Moreover, the interaction between active MoO2 species on the catalyst surface and NC ensured the stability of the catalyst, resulting in no significant loss of activity after four catalytic cycles. 99.5 % and 55.1 % yields of DFF with full conversion were obtained from HMF and fructose respectively over Mo/NC‐chitosan‐600 in DMSO under ambient air. In order to enhance DFF yield from fructose, sulfonate groups were introduced into Mo/NC‐chitosan‐600 catalyst, leading to the highest DFF yield of 70.2 %. In addition, this catalyst also allowed 10.0%, 22.9% and 33.3% DFF yields from glucose, sucrose and inulin, respectively.

Interplay of Size and Magnetic Effects in Electrocatalytic Water Oxidation Activity of Sub-10 nm NiOx Supported Porous Hard-Carbons.

This report describes a systematic approach for precise engineering of a catalyst-metal oxide interface through combining complementary approaches of chemical vapor deposition and atomic layer deposition. Specifically, Chemical Vapor Deposition (CVD) fabricated nanostructured hard-carbon framework (NCF) is employed as synergistic support for precise deposition of NiOx particles through Atomic Layer Deposition (ALD). The three variants of NCF-NiOx system (dimensions ranging from 3-12 nm, surface coverage ranging from 0.14 %-2 %) achieved exhibit unique electrocatalytic water oxidation activities, that are further strongly influenced by an external magnetic field (Hext). This confluence of size engineering and associated magnetic field effects interplay to produce the largest lowering in Rct at Hext=200 mT. A comprehensive analysis of electrocatalytic parameters including the Tafel slope and double layer capacitance establishes further insights on co-relation of size effect and magnetic properties to understand the role of nanocarbon supported transition metal oxides in water electrolysis.

Advanced Oxidation Processes for the oxyfunctionalisation of 1,2-dichlorobenzene: a review

Catalytic oxidation is an oxidation process that converts volatile organics and water carbon in the presence of the catalyst. A catalyst is a substance that is used to accelerate the rate of reaction at a given temperature without itself being consumed during the reaction and it can be used repeatedly. This review presents catalytic oxidation of ortho-dichlorobenzene over V2O5 loaded metal oxides (TiO2, SiO2 and Al2O3), supported transition metal oxides, ABO3- type perovskites and Ca-doped FeOx hollow microspheres. The review reveals different reaction conditions in which different catalysts were used during the degradation of 1,2-dichlorobenzene. The catalytic activity performance is reviewed and compared for all the catalysts used during the degradation of 1,2-dichlorobenzene. In our previous study, catalytic oxidation of orthodichlorobenzene in the presence of ozone and the catalyst at ambient reaction conditions was studied.

Effective hydrodeoxygenation bio-oil via natural zeolite supported transition metal oxide catalyst

Bio-oil from biomass pyrolysis is promising to be used as a sustainable biofuel and high-value-added chemical. However, the presence of high acid, water, and oxygenate causes corrosive properties, low higher heating value (HHV), and instability of the bio-oil component. Therefore, refining the bio-oil is essential to improve its quality. In this study, we introduced natural zeolite (HZ) impregnated with transition metal oxide (TMO) to refine the bio-oil using the hydrodeoxygenation method (HDO) at various catalyst ratios and temperatures. We find that ZnO/HZ 5% wt. shows the best catalytic performance, with the conversion of organic phase reaching ∼ 50%. The refined bio-oil from Fe2O3, ZnO, and CuO has high-quality physicochemical properties with carbon, oxygen, water level, and HHV values are 37–52%, 40–53%, 8–27%, and 17–21 MJ/kg, respectively. This result represents a high catalytic performance for the hydrodeoxygenation process of bio-oil using natural zeolite-based transition metal oxide for better and low-cost biofuel production.

Preparation of a transition metal-supported TiO2 catalyst and the catalytic oxidative degradation of toluene

The synthesis of supported transition metal oxides with satisfactory low-temperature catalytic performance and application potential is still a challenge for the complete degradation of VOCs. Ni-Cu-loaded TiO2 catalysts were prepared by an impregnation method. The lattice defect and oxygen vacancy concentrations of the prepared materials could be tuned by controlling the Ni/Cu molar ratio and the mass proportion of the TiO2 support. 5Ni-Cu/TiO2 exhibited the best catalytic activity and showed superior catalytic stability during complete toluene oxidation. The obtained catalysts were fully characterized by XRD, FT-IR, TEM, N2 adsorption analysis, XPS, H2-TPR, O2-TPD, TPD analysis, and XPS. The 5Ni-Cu/TiO2 catalyst had improved pore sizes and specific surface area, had more oxygen vacancies on its surface, had increased concentrations of adsorbed and lattice oxygen species, and had good redox properties; these characteristics were favorable for low-temperature catalytic performance and catalytic stability. Cyclic transformations of metal valence states between Cu+ and Cu and between Ni and Ni2+ were observed in the catalytic system. A potential catalytic reaction process based on the M-vK mechanism was proposed. This work serves as a reference for the application of supported transition metal catalysts for the degradation of VOCs.

Facet-Induced Strong Metal Chloride−Support Interaction over CuCl2/γ-Al2O3 Catalyst to Enhance Ethylene Oxychlorination Performance

The supported transition metal oxides, chlorides, carbides, and so forth (MXn), represent an important type of catalyst for redox processes. The MXn–support interaction, analogous to metal-support interaction, plays a critical role in redox reactions. Herein, we illustrated the nature of the monolayer CuCl2–γ-Al2O3 interaction, and its catalytic consequence induced by support facets in ethylene oxychlorination. Kinetic and theoretical studies, combined with operando spectroscopy demonstrated the effects of the interaction between CuCl2 with the various exposed facets of γ-Al2O3 (110) and (100). The catalyst with Al2O3(110) shows better performance with high activity, selectivity, and stability. The catalyst with the (111) facet deactivated rapidly, and the ethylene dichloride (EDC) selectivity decreased to 30%; while the activity on the catalyst with the (110) facet was much higher, with the EDC selectivity can be well kept at >99% in the long-term stability test. The multi-scale and in-depth characterizations revealed the concept of metal chloride–support interaction in determining the catalytic performance. We believe this method of tuning the reactivity of active species by manipulating their coordination with the support surfaces as a ligand shall spark inspiration for other catalytic applications.

Oxidation of Toluene by Ozone over Surface-Modified γ-Al2O3: Effect of Ag Addition

In this study, the ability of ozone to oxidise toluene present in low levels into CO and CO2 was studied. The catalytic ozonation of toluene was carried out in a micro-fixed bed reactor. The oxidation was done in two steps: toluene adsorption on the catalyst followed by sequential ozone desorption. Toluene breakdown by ozone at low temperature and atmospheric pressure was achieved using γ-Al2O3 supported transition metal oxides impregnated with a reduced noble metal. The catalyst Ag–CoOx/γ-Al2O3 efficiently oxidised and transformed toluene into products (52.4% COx yield). This catalyst has a high surface area, more acidic sites, and lattice oxygens for better toluene oxidation. The addition of Ag to the CoOx/γ-Al2O3 catalyst surface improved toluene adsorption on the catalyst surface, resulting in improved product yield, selectivity, and carbon balance.

Study on catalytic performance of supported transition metal oxide catalyst for ozone decomposition

In this paper, γ-Al2O3 supported nickel, manganese, cobalt, and other metal oxide catalysts were prepared by the impregnation method respectively, and its ozone catalytic decomposition performance was studied at 25°C under a WHSV of 200000 mL/(gcat·h). The results showed that 10% NiO/γ-Al2O3 catalyst demonstrates superior catalytic activity, and the ozone conversion rate is higher than 96% within 20 h. According to the characterizations of XRD, XPS, TEM, SEM-EDS and H2-TPR, its excellent ozone may be attributed to the formation of NiAl2O4 spinel on the surface of NiO/γ-Al2O3 catalyst. Furthermore, the mechanism of ozone decomposition on different transition metal oxide catalysts is divergent. The related study sheds new light on the reaction mechanism of ozone catalytic decomposition over transition metal oxides such as nickel and manganese, it also provides the guidelines for the development of efficient ozone decomposition catalysts.

In-situ DRIFTS study of chemically etched CeO2 nanorods supported transition metal oxide catalysts

• Effect of NaBH 4 chemical etching on the reducibility of CeO 2 nanorods. • CO adsorption band for polydentate carbonate is found from in situ DRITFS as a result of NaBH 4 etching. • Surface defects obtained by NaHB 4 chemical etching are critical to strong TM (TM-transition metals: Cu, Co, Ni, Fe, Mn)-CeO 2 interactions, therefore resulting in the improved low temperature catalytic activity. In this work, hydrothermally synthesized CeO 2 nanorods (CeO 2 NR) were chemically etched by strong reducing agent NaBH 4 with 0.6~30 wt% addition, and further transition metal (TM) oxides (TM: Cu, Co, Ni, Fe and Mn) were loaded on the surface modified 6 wt% NaBH 4 CeO 2 NR powder (mCeO 2 NR) to prepare mCeO 2 NR supported TM oxide catalysts. Both mCeO 2 NR supports (treated by 0.6–30 wt% NaBH 4 ) and mCeO 2 NR supported TM oxide catalysts were employed to investigate the effect of chemical etching on their surface structure, CO adsorption, CO 2 desorption and catalytic performance. Compared with pristine CeO 2 NR, one strong CO adsorption band for polydentate carbonate is found from in situ DRITFS as a result of NaBH 4 etching, which can explain the enhanced low temperature reducibility and catalytic performance of mCeO 2 NR supports and mCeO 2 NR supported TM oxide catalysts. The vibrational band signals of bicarbonate, monodentate/bidentate/polydentate carbonate and bridged carbonate are detected in all mCeO 2 NR supported TM catalysts and the effect of CO adsorption mode on CO oxidation activity is discussed.

Selective catalytic reduction of NOx in marine engine exhaust gas over supported transition metal oxide catalysts

The selective catalytic reduction (SCR) of nitrogen oxides (NOx) in the presence of methanol (methanol-SCR) was investigated over commercial oxide (γ-Al2O3 and TiO2) supported transition-metal oxide catalysts in lab scale. Of all the prepared catalysts, CuO/γ-Al2O3 catalyst exhibited the highest reduction efficiency in the methanol-SCR process. The practical test results in a marine engine further showed that the 2 wt% CuO/γ-Al2O3 catalyst can remove 93.9% of NOx without catalyst deactivation in several hours. Evidenced by relevant characterization results, the fast-redox properties of copper and rich acidic sites of γ-Al2O3 support were responsible for the excellent catalytic activity of the CuO/γ-Al2O3 catalyst. Revealed by In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), formate-like species derived from methanol dehydrogenation act as the reaction intermediates for NOx reduction. Moreover, this work provides a novel process to reduce NOx and make use of adverse hydrocarbons in the flue gas simultaneously, opening a new research direction in NOx reduction technologies.

Ti3C2 supported transition metal oxides and silver as catalysts toward efficient electricity generation in microbial fuel cells

The improved electricity generation performance of MFCs could be attributed to the Ti3C2 support and the synergistic effect between transition metal oxides and silver for ORR.

Comment on “Direct Decomposition of NOx over TiO2 Supported Transition Metal Oxides at Low Temperatures”

ADVERTISEMENT RETURN TO ISSUEPREVCorrespondenceNEXTORIGINAL ARTICLEThis notice is a correctionComment on “Direct Decomposition of NOx over TiO2 Supported Transition Metal Oxides at Low Temperatures”Josefine Schnee*Josefine SchneeSorbonne Université, CNRS, Laboratoire de Réactivité de Surface (LRS), Tour 43, Case 178, 4, Place Jussieu, F-75252 Paris Cedex 05, France*E-mail: [email protected] (J. Schnee).More by Josefine Schneehttp://orcid.org/0000-0001-8521-9922, Laurent DelannoyLaurent DelannoySorbonne Université, CNRS, Laboratoire de Réactivité de Surface (LRS), Tour 43, Case 178, 4, Place Jussieu, F-75252 Paris Cedex 05, FranceMore by Laurent Delannoy, Guylène CostentinGuylène CostentinSorbonne Université, CNRS, Laboratoire de Réactivité de Surface (LRS), Tour 43, Case 178, 4, Place Jussieu, F-75252 Paris Cedex 05, FranceMore by Guylène Costentinhttp://orcid.org/0000-0003-1559-6890, Frédéric MeunierFrédéric MeunierUniv Lyon, Université Claude Bernard Lyon 1, CNRS, Institut de Recherches sur la Catalyse et l’Environnement de Lyon, IRCELYON, 2, Av. Albert Einstein, F-69626 Villeurbanne, FranceMore by Frédéric Meunierhttp://orcid.org/0000-0001-7953-2883, and Cyril Thomas*Cyril ThomasSorbonne Université, CNRS, Laboratoire de Réactivité de Surface (LRS), Tour 43, Case 178, 4, Place Jussieu, F-75252 Paris Cedex 05, France*E-mail: [email protected] (C. Thomas).More by Cyril Thomashttp://orcid.org/0000-0003-4224-6095Cite this: Ind. Eng. Chem. Res. 2020, 59, 10, 4835–4837Publication Date (Web):February 21, 2020Publication History Published online21 February 2020Published inissue 11 March 2020https://doi.org/10.1021/acs.iecr.0c00412Copyright © 2020 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views911Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-AlertsSUBJECTS:Animal feed,Catalysts,Organic reactions,Oxides,Transition metals Get e-Alerts

Identifying properties of low-loaded CoOX/CeO2 via X-ray absorption spectroscopy for NO reduction by CO

The speciation and catalytic activity of ceria supported transition metal oxides synthesized via incipient wetness impregnation are highly dependent on synthesis parameters such as the choice of metal precursor and the concentration of defects such as oxygen vacancies in the support. Here, cobalt oxide domains were synthesized on cerium oxide nanorods and commercial nanopowder via incipient wetness impregnation of cobalt (II) nitrate hexahydrate, cobalt (II) acetate, cobalt (III) acetylacetonate, and disodium cobalt (II) ethylenediaminetetraacetic acid at surface densities below monolayer coverage. Their reactivity was tested in the catalytic reduction of NO by CO. The steady-state deNOx activity at 250 °C of the catalyst prepared with cobalt (III) acetylacetonate and ceria nanorods was nearly three times greater than that of the control catalyst. From X-ray absorption spectroscopy it was seen that as-deposited cobalt precursors on a nanorod support were more highly coordinated than were cobalt precursors on comparable commercial ceria nanoparticles, possibly indicating anchoring at defects on the nanorods. A relationship was found between catalyst activity and the cobalt oxidation state of the fully calcined catalysts that suggests that deNOx activity is separately dependent on the cobalt oxide distribution and the presence of defects in the support. Overall, here it is shown that the two critical synthesis parameters of ligand choice and defected supports combine additively to improve reactivity of the supported cobalt oxide.

Activated carbon-supported catalyst loading of CH4N2O for selective reduction of NO from flue gas at low temperatures

Selective catalytic reduction of nitrogen oxides with loaded CH4N2O (low-temperature urea-SCR) is a novel and promising technology to remove nitrogen oxides from low-temperature oxygen-containing flue gas, which can avoid the problem of NH3 escape. In the present study, a series of industrial-grade biomass-based activated carbon (AC)-supported transition metal oxide catalysts with urea loading were prepared by ultrasound-assisted impregnation, and the physicochemical properties of the catalysts were observed by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), graphite furnace atomic absorption spectroscopy (GFAAS), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) analysis, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The influences of the AC type, reaction temperature, AC particle size, metal oxide loading, urea load level and loaded active element type on the catalytic activity were studied through experiments. Moreover, the NO adsorption capacities of the AC carrier at different temperatures were also tested and calculated. The results of NO adsorption tests show that the adsorption capacity of AC decreased with increasing temperature. The results of the catalytic performance tests indicate that the copper- and manganese-based catalysts with 6 wt% urea exhibited better activity than the other catalysts. The copper-based catalyst, in particular, yielded better than 93% NO conversion at low temperatures (50–100 °C). Finally, on the basis of the combined characterization results and thermodynamics analysis, a NO removal mechanism of the copper- and manganese-based catalysts was proposed and discussed; the electron transfers of Mn4+ ⇌ Mn2+ and Cu2+ ⇌ Cu0 promoted the low-temperature urea-SCR method.

Tuning the configuration of dispersed oxometallic sites in supported transition metal oxide catalysts: A temperature dependent Raman study

Abstract The speciation of the deposited MOx phase (M = ReVII, MoVI, WVI) in titania-supported transition metal oxide catalysts is studied by in situ Raman spectroscopy under dehydrated conditions at temperatures up to 430 °C. An astonishing temperature-dependent heterogeneity is established for MOx phases at coverages roughly less than half the monolayer. Unlimited cycling between the majority high temperature mono-oxo termination configuration (Ti–O)nM=O and the di-oxo termination configuration (Ti–O)n-1M(=O)2 that predominates at intermediate temperatures (e.g. 100–150 °C) can be achieved by appropriate temperature control and adequate exposure. Support surface hydroxyls and retained water molecules mediate the structural transformation following a proposed molecular level mechanism. Monolayer catalysts (e.g. 5.9 Mo/nm2) do not exhibit the reported effect due to the complete titration of support surface hydroxyls during the deposition stage. The inherent extent of hydroxylation of the support affects the extent of the reversible transformation. As a paradigm, a higher degree of reversible transformation is observed for TiO2(P25)–supported catalysts compared to TiO2(anatase)–supported counterparts due to the well-established higher hydroxylation of the former TiO2(P25) support material. TGA analysis and Raman measurements under static equilibrium ( p O 2 = 0.23 atm ) in evacuated and sealed cells extending also in the hydroxyl stretching region further complement the in situ Raman experiments.

Direct Decomposition of NOx over TiO2 Supported Transition Metal Oxides at Low Temperatures

TiO2 supported transition metal oxides were investigated for the direct decomposition of nitrogen oxides (NOx) at lower temperatures. The results showed that the catalytic performance strongly depends on the kind of transition metal oxide deposited on the TiO2. Among the various catalysts examined, Mn/TiO2 and Co/TiO2 exhibited relatively high NOx conversion at lower temperatures in the presence of 3 vol % O2. The oxygen in the reaction stream had a positive impact on the NOx decomposition over the Mn/TiO2 catalyst. We have not observed any TiO2 phase conversion from anatase to rutile in the Mn/TiO2 during the NOx decomposition reaction at different temperatures (100–350 °C). NOx decomposition activity was shown to be governed by the surface labile oxygen rather than the gas phase oxygen. The Mn/TiO2 catalyst exhibited a good resistance to 10 vol % H2O and 100 ppm of SO2.

Structural Dynamics of Dispersed Titania During Dehydration and Oxidative Dehydrogenation Studied by In Situ UV Raman Spectroscopy

The structural dynamics of dispersed titania, i.e., silica supported titania, is investigated during dehydration and oxidative dehydrogenation (ODH) of ethanol using optical spectroscopy. UV Raman spectroscopy enabling resonance enhancements proves to be a valuable tool to identify Ti–OH, Ti–O–Si, and Ti–O–Ti groups. Upon dehydration, a transformation of Ti–OH into Ti–O–Si and Ti–O–Ti groups is observed. Two types of Ti–OH vibrations (isolated, geminal) are identified at around 700 and 800 cm− 1 in agreement with theoretical models. Dispersed titania is catalytically active in ethanol ODH with a performance comparable to dispersed vanadia. In situ UV Raman spectra reveal a consumption of Ti–O–Ti, Ti–O–Si, and Ti–OH groups during ethanol adsorption to the titania surface. The presented results are consistent with an ODH reaction mechanism involving a structural transformation of oligomerized or closely neighbored monomeric TiOX structures. The relevance of the proposed mechanism is discussed in the context of other supported transition metal oxide catalysts.

Hierarchical hybrid sandwiched structure of ultrathin graphene nanosheets enwrapped MnO nanooctahedra with excellent lithium storage capability

Graphene supported transition metal oxides (TMOs) nanocomposites have been recognized as an advisable strategy to develop the advanced electrodes for lithium-ion batteries (LIB) recently, yet the long-term cyclic stability could not be well maintained mainly due to the severe structural collapse and continuous exfoliation of active TMOs from graphene support. Herein, we successfully designed a novel sandwich-type hybrid nanostructure of reduced graphene oxide (rGO) enwrapped MnO nanooctahedra like a blanket (MnO@rGO NO) via a facile solution reflux and a post-annealing. The XRD patterns and FESEM images confirm that octahedral Mn3O4 precursor embedded among GO interlayers could be easily reduced into conformal MnO nanocrystal whilst the full reduction of GO into rGO during the subsequent calcination at 700 °C in N2. When used as a promising anode for LIBs, the sandwiched MnO@rGO NO manifests excellent lithium storage capability with high reversible discharge capacity, long-term cyclic stability and superb rate performance, mainly benefiting from the robust structure and good conductivity enhanced by rGO matrix. Even undergoing 600 cycles at the current densities of 400 and 800 mA g−1, the hybrid sandwiched MnO@rGO NO anodes could still deliver stable discharge capacities of 838 and 687 mAh g−1, respectively.

Heterogeneity of deposited phases in supported transition metal oxide catalysts: reversible temperature-dependent evolution of molecular structures and configurations.

In situ high-temperature Raman spectroscopy under steady state oxidative dehydrated conditions was used for determining the temperature dependence of the molecular structures and configurations of (MOx)n (M = Re, Mo, W) sites supported at low submonolayer loadings on TiO2(P25). Prior to the Raman analysis, the studied catalyst samples underwent calcination at 450-480 °C for 4-5 h. Regularly repeated random sequences of heating and cooling under flowing 20%O2/He (in the absence of incoming water vapor) in the 35-430 °C temperature range were shown to cause drastic changes in the vibrational properties of the M-O stretching modes and in the molecular structures and configurations of the deposited ReOx, MoOx, and WOx sites in a reversible and reproducible manner. A heterogeneity of the deposited oxometallic phase was evidenced with three distinctly different species (i.e., MOx-I, MOx-II, and MOx-III) present in each system, each one prevailing in a particular temperature range. It was shown that the temperature could tune the molecular structure of the deposited oxometallic phase presumably on account of minima in the surface free energy. In the direction of temperature lowering, a mechanism leading to a hydrolysis-like of the anchoring bonds by activation of the surface hydroxyls and/or water molecules extant on the uncovered TiO2(P25) surface took place. In situ FTIR spectroscopy under identical conditions and similar temperature sequence protocols complemented the Raman results and corroborated the proposed prevailing configurations and pertinent band assignments.