Adsorption of Phosphonic Acid at the TiO₂ Anatase (101) and Rutile (110) Surfaces

Abstract

The adsorption of phosphonic acid on the TiO2 anatase (101) and rutile (110) surfaces have been investigated by means of efficient density-functional-based tight-binding calculations. We studied the geometries and adsorption energies of several adsorption models to achieve clarification of the discrepancy in the experimental finding of a preferred binding state. In this paper we show that there are several adsorption structures likely to be present on the specific TiO2 surfaces. Those structures have exclusively a bidentate configuration. They have similar adsorption energies but different geometries. For the monodentate complexes, we find a strong trend of the adsorption geometry relaxing toward the bidentate coordination. Also, they have significantly smaller adsorption energies. Furthermore, we extensively demonstrate the reliability of the SCC-DFTB method for this chemical system, which opens the way for studies of adsorption on more complex titania materials.

Effect of Ionic Compounds of Different Valences on the Stability of Titanium Oxide Colloids

“…The dispersions became unstable again at high ionic strength, since charge screening by the salt constituents occurred. The specific interaction between phosphate anions of different valences and titania particle surfaces has already been observed in other systems too [73][74][75][76]. On the basis of results from experimental (infrared (IR) spectroscopy) and theoretical (efficient density-functional-based tight-binding calculations) methods, it was suggested that a primary chemical bond was established between the metal ions on the surface and the oxygen atom of the phosphate ions and this interaction gives rise to the accumulation of negative charges on the particle surface.…”

“…The electrokinetic potentials increased in magnitude by increasing the valence of the anions indicating their adsorption on the like-charged surface. The adsorption of the H2PO4 2− was much stronger compared to the SO4 2− of the same valence due to the specific interaction with the surface metal ions through primary chemical bonds [73][74][75][76]. The stability ratio plots contained slow and fast aggregation regimes separated by the CCIS values, which increased in the SO4 2− < Fe(CN)6 3− < Fe(CN)6 4− < H2PO4 2− order.…”

Photoinduced electron transfer processes in dye-semiconductor systems with different spacer groups

“…Since the differences of the adsorption energies between the different binding motifs are rather small, it is expected that several binding motifs will coexist. 69,108 In the present work, we have considered in all cases a bidentate dissociative bridge binding between the adsorbate and the substrate. The proton detached from the carboxylic-acid group is attached to a surface oxygen atom.…”

Interfacial Electron Transfer Dynamics Following Laser Flash Photolysis of [Ru(bpy)2((4,4′‐PO3H2)2bpy)]2+ in TiO2 Nanoparticle Films in Aqueous Environments

“…[15][16][17][18] Experimental Section Materials Aqueous solutions were prepared from water purified by use of a MilliQ purification system. Lithium perchlorate (98 % purity), 70 % perchloric acid (99.999 % purity), chloroplatinic acid (H 2 PtCl 6 ), titanium isopropoxide (97 % purity), isopropanol, hydroxypropylcellulose, zirconium isopropoxide, and Carbowax 20M were used as received from Sigma-Aldrich.…”