Reactions of Hydrazoic Acid and Trimethylindium on TiO₂ Rutile (110) Surface:  A Computational Study on the Formation of the First Monolayer InN

Abstract

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.

The mechanism of the water-gas shift reaction on Cu/TiO2(110) elucidated from application of density-functional theory

“…31 We tested this surface model likewise for its reliability in computing the adsorption energy of H 2 O on the TiO 2 (110) surface; the result, À64.08 kJ mol À1 with the bottom layer fixed, is consistent with the trend of the infinite-slab estimation, within the range from À50.16 to À83.60 kJ mol À1 . [32][33][34][35] The structures and vibrational wavenumbers of isolated gas-phase molecules H 2 O, OH, H 2 , CO 2 and CO were examined on embedding these species in a large unit cell of dimensions 25 Â 25 Â 25 A ˚3. As can be seen in Table 1, our calculated properties agree satisfactorily with the experimental values.…”

Role of Hydroxyl Groups in the NHx (x = 1−3) Adsorption on the TiO2 Anatase (101) Surface Determined by a First-Principles Study

“…To achieve better device functionality of dye-sensitizer solar cells, − different kinds of gas-phase molecules have been reacted with the TiO 2 surface at the Ti cation site (or O anion site) to form specific adsorbates that functionalize the TiO 2 surface. The adsorbates may then act as precursors − that allow gas molecules to subsequently react, anchoring groups − that provide better electron transfer or doping molecules − that narrow the band gap or band shift , to increase the photovoltaic efficiency. Thus, understanding the reactivity of gas molecules and the reaction mechanism is not only of fundamental scientific interest but also of use in anticipating the success of an engineering process.…”

Adsorption Configuration and Dissociative Reaction of NH3 on Anatase (101) Surface with and without Hydroxyl Groups

“…Thus, it is very important for use in solar cell applications to find a more durable inorganic material that has the same broadband adsorption feature. N-doped TiO 2 (TiO 2- x N x ) powders have been shown to have a noticeable improvement over pure TiO 2 under visible light in their optical adsorption and level of photocatalytic activities in the visible range. , In a method similar to that of the solar cell fabrication of the N-doping of TiO 2 film, Wang et al have succeeded in depositing InN thin films by OMCVD (organometallic chemical vapor deposition) on TiO 2 nanoparticles using HN 3 as an N-precursor. , Though its dissociation on some specific surfaces might be low, HN 3 possesses highly explosive and toxic characteristics. Conversely, NH 3 is relatively stable and one of the most highly produced inorganic chemicals to serve as the N- precursor for most of the N-doped TiO 2 − .…”