Preparation, characterization, and application of titanium nano-tube array in dye-sensitized solar cells

The vertically orientated TiO2 nanotube array (TNA) decorated with TiO2 nano-particles was successfully fabricated by electrochemically anodizing titanium (Ti) foils followed by Ti-precursor post-treatment and annealing process. The TNA morphology characterized by SEM and TEM was found to be filled with TiO2 nano-particles interior and exterior of the TiO2 nano-tubes after titanium (IV) n-butoxide (TnB) treatment, whereas TiO2 nano-particles were only found inside of TiO2 nano-tubes upon titanium tetrachloride (TiCl4) treatment. The efficiency in TNA-based DSSCs was improved by both TnB and TiCl4 treatment presumably due to the increase of dye adsorption

Preparation and Characterization of Pure Rutile TiO 2

Pure rutile-phase TiO2 (r-TiO2) was synthesized by a simple one pot experiment under hydrothermal condition using titanium (IV) n-butoxide as a Ti-precursor and HCl as a peptizer. The TiO2 products were characterized by XRD, TEM, ESCA, and BET surface area measurement. The r-TiO2 were rodlike in shape with average size of ∼61×32 nm at hydrothermal temperature of 220°C for 10 h. Hydrothermal treatment at longer reaction time increased the tendency of crystal growth and also decreased the BET surface area. The degradation of methylene blue was selected as a test reaction to confer the photocatalytic activity of as-obtained r-TiO2. The results showed a strong correlation between the structure evolution, particle size, and photocatalytic performance of r-TiO2. Furthermore, the r-TiO2-based solar cell was prepared for the photovoltaic characteristics study, and the best efficiency of ~3.16% was obtained

Preparation of Smooth Surface TiO 2

Dye-sensitized solar cells (DSSCs) based on a TiO2 photoanode have been considered as an alternative source in the field of renewable energy resources. In DSSCs, photoanode plays a key role to achieve excellent photo-to-electric conversion efficiency. The surface morphology, surface area, TiO2 crystal phase, and the dispersion of TiO2 nanoparticles are the most important factors influencing the properties of a photoanode. The smooth TiO2 surface morphology of the photoanode indicates closely packed arrangement of TiO2 particles which enhance the light harvesting efficiency of the cell. In this paper, a smooth TiO2 photoanode has been successfully prepared using a well-dispersed anatase TiO2 nanosol via a simple hydrothermal process. The above TiO2 photoanode was then compared with the photoanode made from commercial TiO2 nanoparticle pastes. The morphological and structural analyses of both the aforementioned photoanodes were comprehensively characterized by scanning electron microscopy and X-ray diffraction analysis. The DSSC fabricated by using a-TiO2 nanosol-based photoelectrode exhibited an overall light conversion efficiency of 7.20% and a short-circuit current density of 13.34 mA cm−2, which was significantly higher than those of the DSSCs with the TiO2 nanoparticles-based electrodes

The Stabilization of Waste Funnel Glass of CRT by SiO2 Film Coating Technique

The funnel glass of the CRT monitor contains about 22–28% of lead oxide, of which lead is a highly toxic species and hazardous to the environment. This study proposes a process to form a protective layer of SiO2 film coating on the funnel glass to reduce the hazardous effect of lead leaching to the environment. The film coating benefits from the advantages of the sol–gel method. There are two key procedures of the stabilization technique, including the alkaline treatment and the formation of SiO2 coating from TEOS. The results show that the funnel glass powder treated with 10 M NaOH can produce a mushy layer on the surface. The mushy layer, which comprises OH− and water, can promote the formation of the SiO2 film layer on the surface of funnel glass powder. The conditions of the SiO2 film coating proposed in this study are: alkaline treatment by 10 M NaOH, the addition ratio of TEOS and funnel glass powder 2: 1, reaction temperature 40 °C, and reaction time 1.3 h. The EDS and ESCA results show that the Pb peak intensity on the surface of funnel glass decreases with the film coating. In the TCLP test, the leaching amount for Pb of the SiO2 film coated funnel glass powders is 0.7 mg/L, which is far lower than the standard in Taiwan EPA. Based on the experimental results, the formation mechanism of the SiO2 film layer on the surface of waste funnel glass powder is proposed. This study demonstrates that the SiO2 film coating is a potentially effective method to solve the problem of the waste funnel glass

Research Insights and Challenges of Secondary School Energy Education: A Dye-Sensitized Solar Cells Case Study

The research achievements of a university chemistry lab regarding dye-sensitized solar cells (DSSCs) were transformed into a high school hands-on course by simplifying the experimental steps and equipment. Our research methodology was action research. We verified the DSSC course step by step. First, 10 members of a high school science study club helped to revise the course over a school semester. A questionnaire survey revealed that all students agreed that the course increased their understanding of DSSCs and solar cells. Second, 35 students were enrolled in a 10th-grade elective energy course to study the revised DSSC topics for 3 weeks. A five-point Likert scale was used to collect students’ feedback, and students reported looking forward to making their own high-performance DSSC modules (4.60) and stated that being able to make their own solar cell was a great accomplishment (4.49). Third, the course was implemented at a junior high school science camp, and the 37 participating students were all able to complete the hands-on experiment. In the questionnaire survey, the students expressed that they enjoyed learning about scientific principles through a hands-on approach (4.59). Fourth, most of the 12 schoolteachers who voluntarily participated in the DSSC workshop agreed that integrating DSSC activity into school courses would be conducive to multidisciplinary learning. This course could facilitate participants’ self-evaluations in science knowledge, experimental skills, learning motivations, and positive attitudes toward sustainability

Hydrogen-Containing Na3HTi1- xMnxF8 Narrow-Band Phosphor for Light-Emitting Diodes

We synthesize the phosphor Na3HTi1-xMnxF8 (Na3HTiF8:Mn4+) material series using a coprecipitation method. We determine the complete phase and crystallographic structure of the Na3HTiF8 series end-member, including the determination of the H atoms at the 4b (0, 1/2, 0) crystallographic site within the Cmcm space group symmetry structure, resulting in a quantum efficiency of ∼44%, which is comparative to the Na2SiF6:Mn4+ phosphor materials. We successfully model the luminescent properties of the Na3HTi1-xMnxF8 material series, including temperature and time-dependent photoluminescence, providing a good prediction of the decay properties at low and high temperature and revealing the existence of Mn5+ during the ionization process. Notably, LED package data indicates that the Na3HTi1-xMnxF8 material series could be a promising candidate for high-level and back-lighting devices. This research reveals the role that hydrogen plays in determining fluoride phosphor structure and properties, revealing a new path for the synthesis of fluoride phosphors

Probing Eu2+ luminescence from different crystallographic sites in Ca10M(PO4)7:Eu2+ (M = Li, Na and K) with beta-Ca3(PO4)2-type structure

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Eu2+ local environments in various crystallographic sites ena-bles the different distribution of the emission and excitation energies, and then realize the photoluminescence tuning of the Eu2+ doped solid state phosphors. Herein we report the Eu2+-doped Ca10M(PO4)7 (M = Li, Na and K) phosphors with β-Ca3(PO4)2-type structure, in which there are five cations crystallographic sites, and the phosphors show a color tuning from bluish-violet to blue and yellow with the variation of M ions. The difference in decay rate monitored at selected wavelength is related with multiple luminescent centers in Ca10M(PO4)7:Eu2+, and the occupied rates of Eu2+ in Ca(1), Ca(2), Ca(3), Na(4) and Ca(5) sites from Rietveld refine-ments using synchrotron power diffraction data confirm that Eu2+ enters into four cation sites except for Ca(5). Since the average bond lengths d(Ca-O) keep invariable in the Ca10M(PO4)7:Eu2+, the drastic changes of bond lengths d(M-O) and Eu2+ emission depending on the variation from Li to Na and K can provide insight to probe the distribution of Eu2+ ions. It is found that the emission band 410 nm is as-cribed to the occupation of Eu2+ in Ca(1), Ca(2) and Ca(3) sites with similar local environments, while the long-wavelength band (466 nm or 511 nm) is attributed to Eu2+ at M(4) site (M = Na and K). We show that the crystal-site en-gineering approach discussed herein can be applied to probe the luminescence of the dopants and provide a new method for photoluminescence tuning

Probing Eu2+ luminescence from different crystallographic sites in Ca10M(PO4)7:Eu2+ (M = Li, Na and K) with beta-Ca3(PO4)2-type structure

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Eu2+ local environments in various crystallographic sites ena-bles the different distribution of the emission and excitation energies, and then realize the photoluminescence tuning of the Eu2+ doped solid state phosphors. Herein we report the Eu2+-doped Ca10M(PO4)7 (M = Li, Na and K) phosphors with β-Ca3(PO4)2-type structure, in which there are five cations crystallographic sites, and the phosphors show a color tuning from bluish-violet to blue and yellow with the variation of M ions. The difference in decay rate monitored at selected wavelength is related with multiple luminescent centers in Ca10M(PO4)7:Eu2+, and the occupied rates of Eu2+ in Ca(1), Ca(2), Ca(3), Na(4) and Ca(5) sites from Rietveld refine-ments using synchrotron power diffraction data confirm that Eu2+ enters into four cation sites except for Ca(5). Since the average bond lengths d(Ca-O) keep invariable in the Ca10M(PO4)7:Eu2+, the drastic changes of bond lengths d(M-O) and Eu2+ emission depending on the variation from Li to Na and K can provide insight to probe the distribution of Eu2+ ions. It is found that the emission band 410 nm is as-cribed to the occupation of Eu2+ in Ca(1), Ca(2) and Ca(3) sites with similar local environments, while the long-wavelength band (466 nm or 511 nm) is attributed to Eu2+ at M(4) site (M = Na and K). We show that the crystal-site en-gineering approach discussed herein can be applied to probe the luminescence of the dopants and provide a new method for photoluminescence tuning