Bandgap tailoring of rutile TiO2(110) via surface patterning with electron cyclotron resonance sputtering

Abstract

Crystalline TiO 2 nanodots have been formed on single crystal rutile TiO 2 ͑110͒ surfaces via ion beam sputtering method by utilizing Ar ion beams from electron cyclotron resonance source. Nearly five times enhancement in absorbance of visible light, ϳ5 times increase in luminescence, and ϳ0.1 eV narrowing of bandgap are observed for nanodot-patterned surfaces, in the absence of any dopant material. Formation of crystalline rutile TiO 2 nanodots and development of Ti interstitials on the TiO 2 ͑110͒ surface, after ion beam sputtering, are responsible for these observations. Results suggest that these nanodot-patterned rutile TiO 2 surfaces can become effective photocatalysts.

Calculation of TiO2 Surface and Subsurface Oxygen Vacancy by the Screened Exchange Functional

“…Our simulation results are consistent with the experimental surface band gap values in previous studies. 39,40 We have calculated the formation energy of various surface or subsurface neutral oxygen vacancies on all three surfaces in the O-rich condition, as labeled in Figure 1, in both GGA and screened exchange. The most stable ones are listed in Table 1.…”

Intrinsic defects and electronic conductivity of TaON: First-principles insights

“…One key issue for realizing this application is to search for suitable photoelectrode semiconductors which can absorb visible light. [1][2][3] Owing to their good chemical stability in aqueous solution, transition metal oxides are the subject of most previous studies. [2, 4] However, transition metal oxides usually have large band gaps (≥ 3 eV), limiting the absorption of visible light and setting an upper limit on the energy conversion efficiency at ∼2%.…”

Room temperature superparamagnetism in rutile TiO2 quantum dots produced via ECR sputtering

“…2(a) shows the optical reflectance spectra from pristine and ion irradiated TiO 2 surfaces. It displays two absorption band edgesẼ 1, related to direct bandgap transition [12,15] andẼ2, due to oxygen vacancy related transitions [12]. A significant decrease of reflectance, compared to pristine surface, is demonstrated for the nanostructured TiO 2 surfaces.…”

“…[11]. Ion beam irradiation technique is an attractive technique for fabricating nanostructures since via this technique self assembled nanostructures are created in a single step process [12][13][14]. Here, the creation of nanostructures is effectively controlled through a competition between the curvature dependent radiation sputtering that roughens the surface and a variety of smoothening mechanisms.…”