Band Gap Of In2O3 Research Articles

Visible-light absorption of indium oxide thin films via Bi3+ doping for visible-light-responsive photocatalysis

In2O3 is commonly used as a photocatalyst for hydrogen energy storage. However, it has the disadvantage of a large optical bandgap (3.7 eV), resulting in low absorption of visible light, which corresponds to 50 % of sunlight energy. Band engineering is an efficient method to add visible-light responsivity to wide-bandgap In2O3. In this study, the band engineering of In2O3 was performed by incorporating bismuth to obtain an intermediate band that could absorb visible light. Thin films of In2O3 doped with bismuth (IBO) were grown using mist chemical vapor deposition (CVD), and their optical properties were investigated. Transmittance measurements showed that the IBO thin film exhibited absorption in the visible light region of 400–700 nm, indicating that the introduction of bismuth created an intermediate band in the bandgap of In2O3. IBO thin films with platinum as a co-catalyst could almost completely degrade methylene blue under visible light (420 nm) irradiation for 72 h. Thus, the incorporation of bismuth into In2O3 via mist CVD and the strong absorption of visible light owing to its intermediate band were demonstrated. This study demonstrates that IBO thin films with large absorption in the visible-light region are promising materials for visible-light-responsive photocatalysts.

The Itinerant 2D Electron Gas of the Indium Oxide (111) Surface: Implications for Carbon- and Energy-Conversion Applications.

Transparent conducting oxides (TCO) have integral and emerging roles in photovoltaic, thermoelectric energy conversion, and more recently, photocatalytic systems. The functional properties of TCOs, and thus their role in these applications, are often mediated by the bulk electronic band structure but are also strongly influenced by the electronic structure of the native surface 2D electron gas (2DEG), particularly under operating conditions. This study investigates the 2DEG, and its response to changes in chemistry, at the (111) surface of the model TCO In2 O3 , through angle resolved and core level X-ray photoemission spectroscopy. It is found that the itinerant charge carriers of the 2DEG reside in two quantum well subbands penetrating up to 65 Å below the surface. The charge carrier concentration of this 2DEG, and thus the high surface n-type conductivity, emerges from donor-type oxygen vacancies of surface character and proves to be remarkably robust against surface absorbents and contamination. The optical transparency, however, may rely on the presence of ubiquitous surface adsorbed oxygen groups and hydrogen defect states that passivate localized oxygen vacancy states in the bandgap of In2 O3 .

Enhanced photocatalytic activity of porous In2O3 for reduction of CO2 with H2O

In this paper, a series of indium oxides were prepared by calcining the In(OH)3 precursors, which were synthesized by hydrothermal method using the mixed solution of ethylenediamine (En) and water as a solvent. The morphologies, particle sizes, pore structure, crystallinity and surface defect concentration of these photocatalysts were adjusted by varying the ratio of En to water during the preparation of In(OH)3 precursors. The results revealed that In2O3 photocatalysts obtained from the precursor prepared in En containing solvent exhibited much higher photocatalytic activities for CO2 reduction with H2O when compared to that derived from the precursor prepared in pure water. This result can be ascribed to several reasons as following. Firstly, the En addition with a suitable amount can improve the crystallinity of In2O3 and decrease the surface defect concentration, which obviously depressed the recombination of photogenerated electrons and holes. Also, the addition of En during the preparation of precursor can decrease the particle size, increase specific surface area and pore structure, resulting into the increase of active sites. Finally, the band gap of In2O3 can be slightly narrowed after the addition of En, resulting in enhanced light absorption in the visible region. When the ratio of ethylenediamine to water is 1:1, the as-prepared In2O3 possessing the largest specific surface area and pore volume, enhanced light absorption ability and higher hole–electron separation efficiency, exhibited the highest photocatalytic activity. Under visible light irradiation, the H2, CO and CH4 production rates of 5.3, 8.3 and 27.2 µmol/gcat/h can be achieved, respectively.

Effect of Ga incorporation on morphology and defect structures evolution in VLS grown 1D In2O3 nanostructures

Fabrication of 1D metal oxide nanostructures of controlled morphology and defect structure is of immense importance for their application in optoelectronics. While the morphology of these nanostructures depends primarily on growth parameters utilized in physical deposition processes, incorporation of foreign elements or dopants not only affects their morphology, but also affects their crystallinity and defect structure, which are the most important parameters for their device applications. Herein we report on the growth of highly crystalline 1D In2O3 nanostructures through vapor-liquid-solid process at relatively low temperature, and the effect of Ga incorporation on their morphology and defect structures. Through electron microscopy, Raman spectroscopy and cathodoluminescence spectroscopy techniques, we demonstrate that incorporation of Ga in In2O3 nanostructures not only strongly affects their morphology, but also generates new defect levels in the band gap of In2O3, shifting the overall emission of the nanostructures towards visible spectral range.

Dysprosium, Holmium and Erbium ions doped Indium Oxide nanotubes as photoanodes for dye sensitized solar cells and improved device performance

In this work, rare earth (RE) ion RE3+ (RE3+=Dy3+, Ho3+ and Er3+) doped and undoped In2O3 nanotubes are synthesized by the electrospinning method and the band gap of In2O3 is systemically controlled, depending on the order of doped elements. Dye-sensitized solar cells (DSSCs) based on In2O3:RE3+ nanotubes are also fabricated, and significantly improved performance of In2O3–DSSC is observed due to the modulation of the band gap, larger recombination charge transfer resistance and longer electron lifetime.

Electronic structure, mechanical and optical properties of In2O3 with hybrid density functional (HSE06)

In this study, the hybrid density correlation functional (HSE06) is used to explore the electronic structure and optical properties of In2O3, on the basis of density functional theory (DFT). The calculated equilibrium lattice parameters, volume and bulk modulus of this compound, are comparable with the experimental results available in the literature. The bandgap of In2O3 has been a matter of debate in literatures. However, our calculated bandgap can bridge the gap between experiment and theory, and is in good agreement with the available experimental results. Furthermore, we calculate and analyze the optical and mechanical properties of this compound. We hope that our work will help to understand the correct electronic structure and optical properties of this compound.

Excimer laser beam/ITO interaction: from laser processing to surface reaction

AbstractWe investigated interactions between UV light and Indium Tin Oxide (ITO) thin films sputtered at room temperature. Owing to their photon energy, higher than the band gap of In2O3 (3.5–4.0 eV), KrF (5.0 eV) or XeCl (4.0 eV) lasers proved useful, at high fluences (1‐3 J/cm2) for minute laser shaping, at low fluences (100 mJ/cm2) for laser annealing, or even at very low fluences for gases desorption. Sputtered ITO becomes totally amorphous when an oxygen flow is mixed in the process argon and adjusted for the lowest resistivity. As non optimised layers behave like gas sensors, amorphous ITO is immune to atmospheric agents. The band structure of indium oxide and exposures to UV light at selected wavelengths helped to a better understanding of the gas sensing mechanisms on oxygen rich and oxygen poor layers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)