Jenny Schneider,*,† Masaya Matsuoka,‡ Masato Takeuchi,‡ Jinlong Zhang, Yu Horiuchi,‡ Masakazu Anpo,‡ and Detlef W. Bahnemann*,† †Institut fur Technische Chemie, Leibniz Universitaẗ Hannover, Callinstrasse 3, D-30167 Hannover, Germany ‡Faculty of Engineering, Osaka Prefecture University, 1 Gakuen-cho, Sakai Osaka 599-8531, Japan Key Lab for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237, China

Understanding TiO2 photocatalysis: mechanisms and materials.

This paper summarizes recent research dealing with development of titanium dioxide (TiO2) used for environmental applications. TiO2 plays the most important role owing to its excellent chemical and physical properties. However, the TiO2 band edge lies in the UV region that makes them inactive under visible irradiation. In this regard, considerable efforts have been made to increase the visible light activity of TiO2 via the modification of its electronic and optical properties. Doping TiO2 using either anions or cations is one of the typical approaches that has been largely applied. Coupling TiO2 with a narrow bad gap semiconductor (MxOy/TiO2 or MxSy/TiO2) represents another approach. This work aims to encompass the new progress of TiO2 for an efficient application in water and wastewater treatment under visible light, emphasizes the future trends of TiO2 in the environment, and suggests new research directions, including preparation aspects for the development of this promising material.

Modified TiO2 For Environmental Photocatalytic Applications: A Review

This review captures the synthesis, assembly, properties, and applications of copper chalcogenide NCs, which have achieved significant research interest in the last decade due to their compositional and structural versatility. The outstanding functional properties of these materials stems from the relationship between their band structure and defect concentration, including charge carrier concentration and electronic conductivity character, which consequently affects their optoelectronic, optical, and plasmonic properties. This, combined with several metastable crystal phases and stoichiometries and the low energy of formation of defects, makes the reproducible synthesis of these materials, with tunable parameters, remarkable. Further to this, the review captures the progress of the hierarchical assembly of these NCs, which bridges the link between their discrete and collective properties. Their ubiquitous application set has cross-cut energy conversion (photovoltaics, photocatalysis, thermoelectrics), en...

Compound Copper Chalcogenide Nanocrystals

The dynamics of the piezo inkjet printhead operation

Application of doped photocatalysts for organic pollutant degradation - A review

Effects of Ga concentration on electronic and optical properties of Ga-doped ZnO from first principles calculations

This study investigates the formation energies, electronic structures, and optical properties of pure and Si-doped ZnO using density functional theory and the Hubbard U (DFT + Ud + Up) method. The difference in lattice constants between calculated results and experimental measurements is within 1%, and the calculated band gap of pure ZnO is in excellent agreement with experimental values. This study considers three possible Si-doped ZnO structures including the substitution of Si for Zn (Sis(Zn)), interstitial Si in an octahedron (Sii(oct)), and interstitial Si in a tetrahedron (Sii(tet)). Results show that the formation energy of Sis(Zn) defects is the lowest, indicating that Sis(Zn) defects are formed more easily than Sii(oct) and Sii(tet). All three of the Si defect models exhibited n-type conductive characteristics, and except for the Sii(oct) mode the optical band gap expanded beyond that of pure ZnO. In both the Sii(oct) and Sii(tet) models, a heavier effective mass decreased carrier mobility, and deeper donor states significantly decreased transmittance. Therefore, the existence of interestitial Si atoms was bad for the electric and optical properties of ZnO.

https://www.mdpi.com/1996-1944/5/11/2088/pdf

Electronic and Optical Properties of Substitutional and Interstitial Si-Doped ZnO

A three-dimensional computer-aided analysis system has been developed in this study to simulate the formation, ejection, and impact of a liquid droplet in a squeeze-type piezoelectric inkjet printing device. The computer simulation system is based on a solution algorithm (SOLA) scheme for the solution of velocity and pressure fields. It is coupled with volume-of-fluid (VOF) and piecewise-linear interface construction (PLIC) techniques for the transport of F values, which are the volume fractions of liquid in the cells, and construction of the interface. For the treatment of surface tension effects, a CSF (continuum surface force) model is employed. The pressure at the nozzle inlet, which is related to the applied voltage, imposed on the simulation system is determined by the propagation theory of acoustic waves. The simulated results are rather consistent with the experimental observations in terms of droplet morphology, break-up time, flying distance, and droplet volume.

Development of a three-dimensional simulation system for micro-inkjet and its experimental verification

In this study, we reported the synthesis of the two-dimensional (2D) nanocomposite of molybdenum disulfide and nitrogen-doped graphene oxide (MoS2/nGO) as a platinum-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy were used to examine the characteristics of the 2D nanocomposite of MoS2/nGO. The cyclic voltammetry (CV), electrochemical impedance spectra (EIS), and the Tafel polarization measurements were carried out to examine the electrocatalytic abilities. XPS and Raman results showed the 2D behaviors of the prepared nanomaterials. HRTEM micrographs showed the direct evidence of the 2D nanocomposite of MoS2/nGO. The results of electrocatalytic examinations indicated the MoS2/nGO owning the low charge transfer resistance, high electrocatalytic activity, and fast reaction kinetics for the reduction of triiodide to iodide on the electrolyte–electrode interface. The 2D nanocomposite of MoS2/nGO combined the advantages of the high specific surface of nGO and the plenty edge sites of MoS2 and showed the promoted properties different from those of their individual constituents to create a new outstanding property. The DSSC with MoS2/nGO nanocomposite CE showed a photovoltaic conversion efficiency (PCE) of 5.95 % under an illumination of AM 1.5 (100 mW/cm2), which was up to 92.2 % of the DSSC with the conventional platinum (Pt) CE (PCE = 6.43 %). These results reveal the potential of the MoS2/nGO nanocomposite in the use of low-cost, scalable, and efficient Pt-free CEs for DSSCs.

/pdf/the-two-dimensional-nanocomposite-of-molybdenum-disulfide-11s7uou86f.pdf

The Two-Dimensional Nanocomposite of Molybdenum Disulfide and Nitrogen-Doped Graphene Oxide for Efficient Counter Electrode of Dye-Sensitized Solar Cells.

The aim of this study is to investigate the formation and ejection behavior of droplets created by a squeeze mode piezoelectric inkjet printing device using a single pulse voltage pattern. The test liquids are de-ionized (DI) water and ethylene glycol. The experimental results and acoustic wave theory are used to discuss the effects of operating frequency, positive voltage keeping time and pulse voltage magnitude on the volume and velocity of the droplets. For this study, a squeeze mode piezoelectric printhead is employed. By coordinating an LED flash with droplet ejection, a CCD camera could be used to capture images of the droplets at different points in the formation and ejection process. These images were then used to estimate the volume and velocity of the droplets. The experimental results are consistent with the propagation theory of acoustic waves. The maximum allowable pulse frequency in DI water and ethylene glycol are 1500 Hz and 14000 Hz respectively. If the positive voltage keeping time equals the time required for the acoustic wave to propagate through the printhead, optimal ejection behavior is achieved. As the pulse voltage increases, both the velocity and volume of the droplet become larger.

Hsuan-Chung Wu

Papers

Effects of Ga concentration on electronic and optical properties of Ga-doped ZnO from first principles calculations

Electronic and Optical Properties of Substitutional and Interstitial Si-Doped ZnO

Development of a three-dimensional simulation system for micro-inkjet and its experimental verification

The Two-Dimensional Nanocomposite of Molybdenum Disulfide and Nitrogen-Doped Graphene Oxide for Efficient Counter Electrode of Dye-Sensitized Solar Cells.

Study of Micro-Droplet Behavior for a Piezoelectric Inkjet Printing Device Using a Single Pulse Voltage Pattern