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Query: KEGG:D01931 (TiO2)
 11,320 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This article reports the result of a computational study on the reaction of hydrazoic acid and trimethylindium (TMIn), coadsorbed on TiO2 rutile (110) surface. The adsorption geometries and energies of possible adsorbates including HN3-In(CH3)3(a) and its derivatives, HN3-In(CH3)2(a), N3-In(CH3)2(a), N3-In(CH3)(a), and N-In(a), have been predicted by first-principles calculations based on the density functional theory (DFT) and the pseudopotential method. The mechanisms of these surface reactions have also been explicitly elucidated with the computed potential energy surfaces. Starting from the interaction of three stable HN3 adsorbates, HN3-Ob(a), H(N2)N-Ob(a), and Ti-NN(H)N-Ob(a), where Ob is the bridged O site on the surface, with two stable intermediates from the adsorption and dissociative adsorption of TMIn, (H3C)3In-Ob(a) and (H3C)2In-Ob(a)+H3C-Ob(a), InN products can be formed exothermically via four reaction paths following the initial barrierless In-atom association with the N atom directly bonded to H, by CH4 elimination (with approximately 40 kcal/mol barriers), the InN-N bond breaking and the final CH3 elimination or migration (with <20 kcal/mol barriers). These Langmuir-Hinshelwood processes producing the two most stable InN(a) side-on adsorptions confirm that HN3 and TMIn are indeed very efficient precursors for the deposition of InN films on TiO2 nanoparticles. The result of similar calculations for the reactions occurring by the Rideal-Eley mechanism involving HN3(a)+TMIn(g) and HN3(g)+TMIn(a) indicates that they are energetically less favored and produce the less stable InN(a) with end-on configurations.
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PMID:Reactions of hydrazoic acid and trimethylindium on TiO2 rutile (110) surface: a computational study on the formation of the first monolayer InN. 1647 13

This article reports the results of a computational and experimental study on the reaction of hydrazoic acid, HN3, adsorbed on 15-20 nm TiO2 particle films. Experimentally, FTIR spectra of HN3(a) have been measured by varying HN3 dosage, UV irradiation time and surface annealing temperature. Three sharp peaks, related to v(a)(NNN) of HN3(a) and N3(a) with different configurations in the 2000-2200 cm(-1) region, and a broad band absorption, related to associated and isolated HN(a) and HO(a) adsorptions in the 3000-3800 cm(-1) region, have been detected. Computationally, molecular structures, vibrational frequencies and adsorption energies of possible adsorbates including HN3 and its derivatives, N3, N2, NH, and H, have been predicted by first-principles calculations based on the density functional theory (DFT) and the pseudopotential method. On the basis of the experimental and computational results, the peak appeared at 2075 cm(-1), which increases at a faster rate with HN3 exposure time, is attributed to a stable adsorbate, N3-Ti(a), with the predicted adsorption energy, E(ads) = 13 kcal/mol. The peak at 2118 cm(-1), which survives at the highest surface temperature in the heating experiment, is attributable to the most stable adsorbate, Ti-N2N(H)-O(a) with E(ads) = 36 kcal/mol. The peak at 2170 cm(-1), which vanishes most readily in all of the aforementioned experiments, is related to less stable molecular adsorbates, end-on HN3-Ti(a) with E(ads) = 5 kcal/mol and side-on HN(N2)-Ti(a) with E(ads) = 8 kcal/mol. A potential energy diagram for the formation of various absorbates with their transition states has been established for the HN3/TiO2 system. On the basis of the predicted desorption energies, the four most stable products of the HN3 reaction on TiO2 are H-O(a), 118 kcal/mol; HN-O(a), 85 kcal/mol; Ti-N2N(H)-O(a), 36 kcal/mol; and N3-O(a), 19 kcal/mol.
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PMID:Reactions of hydrazoic acid on TiO2 nanoparticles: an experimental and computational study. 1686 76

The reactions of trimethylindium (TMIn) with HN3 and NH3 are relevant to the chemical vapor deposition of indium nitride thin film. The mechanisms and energetics of these reactions in the gas phase have been investigated by density functional theory and ab initio calculations using the CCSD(T)/Lanl2dz//B3LYP/Lanl2dz and CCSD(T)/Lanl2dz//MP2/Lanl2dz methods. The results of both methods are in good agreement for the optimized geometries and relative energies. These results suggest that the reaction with HN3 forms a new stable product, dimethylindiumnitride, CH3-In=N-CH3 via another stable In(CH3)2N3 (dimethylindium azide, DMInA) intermediate. DMInA may undergo unimolecular decomposition to form CH3InNCH3 by two main possible pathways: (1) a stepwise decomposition process through N2 elimination followed by CH3 migration from In to the remaining N atom and (2) a concerted process involving the concurrent CH3 migration and N2 elimination directly giving N2+CH3InNCH3. The reaction of TMIn with NH3 forms a most stable product DMInNH2 following the initial association and CH4-elimination reaction. The required energy barrier for the elimination of the second CH4 molecule from DMInNH2 is 74.2 kcal/mol. Using these reactions, we predict the heats of formation at 0 K for all the products and finally for InN which is 123+/-1 kcal/mol predicted by the two methods. The gas-phase reaction of HN3 with TMIn is compared with that occurring on rutile TiO2 (110). The most noticeable difference is the high endothermicity of the gas-phase reaction for InN production (53 kcal/mol) and the contrasting large exothermicity (195 kcal/mol) released by the low-barrier Langmuir-Hinshelwood type processes following the adsorption of TMIn and HN3 on the surface producing a horizontally adsorbed InN(a), Ti-NIn-O(a), and other products, CH4(g)+N2(g)+2CH3O(a) [J. Phys. Chem. B 2006, 110, 2263].
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PMID:Computational study of reaction pathways for the formation of indium nitride from trimethylindium with HN3: comparison of the reaction with NH3 and that on TiO2 rutile (110) surface. 1738 80