DFT study of coverage-depended adsorption of NH3 on TiO2-B (100) surface

Abstract

A previous study showed that TiO(2)-B (100) surface is very unique. It is characterised by high activity and a loose structure. In this study, we studied the adsorption of ammonia on TiO(2)-B (100) surface at coverages ranging from 1/6 ML to 1 ML using ab initio density functional calculations. We also investigated the adsorption of an isolated ammonia molecule on TiO(2)-B (001) surface to compare the different activities of TiO(2)-B (100) and (001) surfaces towards NH(3). The results showed that the TiO(2)-B (100) surface is more reactive towards NH(3) molecule than TiO(2)-B (001) surface, and the Lewis acid site on TiO(2)-B (100) surface is more acidic. The decrease rate of the average molecular adsorption energy of NH(3) with coverage on TiO(2)-B (100) surface is substantially lower than that on a rutile (011) surface above 1/2 ML coverage due to the open structure of TiO(2)-B (100) surface. The average molecular adsorption energy shows a linear dependence on the coverage of y = 111.0 - 36.3x on TiO(2)-B (100) surface. The possibility of NH(3) molecule onto the Ti(5c) site is nearly equal to forming a dimer with adsorbed NH(3) on TiO(2)-B (100) surface at 5/6 ML coverage.

Comparison of the Thermal and Photochemical Reaction Pathways of Melamine on TiO2

“…[26][27][28] Theoretically, NH 3 adsorption on various TiO 2 model surfaces has been extensively investigated. [29][30][31][32][33][34] These calculations point out that the most stable bonding 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 …”

Experimental Microkinetic Approach of De-NOx by NH3 on V2O5/WO3/TiO2 Catalysts. 1. Individual Heats of Adsorption of Adsorbed NH3 Species on a Sulfate-Free TiO2 Support Using Adsorption Isobars

“…63 In an early study, Markowits et al 64 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 who determined 95 kJ/mol and 110 kJ/mol for the heats of adsorption of NH 3 for TiO 2 nanotubes arrays of 12 and 18 respectively. Guo et al 66 Comparison with surface sciences data.…”

Analysis of Photocatalytic Nitrogen Fixation on Rutile TiO2(110)

“…They concluded that NH 3 and NH 2 adsorb at the 5-fold titanium site, whereas hydrogen could bind at the bridging oxygens or the in-plane oxygen atoms. Several studies have also investigated the binding of ammonia and other nitrogen-containing species on anatase − and monoclinic polymorphs of TiO 2 . Very recently Xie et al used DFT to calculate the energetics of nitric oxide reduction on TiO 2 , and Höskuldsson et al utilized GGA DFT to screen rutile oxides for electrochemical ammonia synthesis, and found a relatively large limiting potential of ca.…”