Photo Energy Research Articles

A novel catalyst for ammonia synthesis at ambient temperature and pressure: Visible light responsive photocatalyst using localized surface plasmon resonance

A novel catalyst for ammonia synthesis using localized surface plasmon resonance (LSPR) was investigated. Os–Au composite nanoparticles showed a high catalytic activity in ammonia synthesis reaction under visible light irradiation at room temperature and atmospheric pressure. Photo energy was likely to be transferred to Os via Au particles, and contributed to the enhancement of the catalytic activity, because the ammonia production rate and the LSPR absorbance of Au particles showed similar dependence on the irradiation wavelength.

Photocatalytic reduction of CO2 to energy products using Cu–TiO2/ZSM-5 and Co–TiO2/ZSM-5 under low energy irradiation

Copper or cobalt incorporated TiO2 supported ZSM-5 catalysts were prepared by a sol–gel method, and then were characterized by XRD, BET, XPS and UV–vis diffuse reflectance spectroscopy. Ti3+ was the main titanium specie in TiO2/ZSM-5 and Cu–TiO2/ZSM-5, which will be oxide to Ti4+ after Co was doped. With the deposition of Cu or Co, the efficiency of the CO2 conversion to CH3OH was increased under low energy irradiation. The peak production rate of CH3OH reached 50.05 and 35.12μmolg−1h−1, respectively. High photo energy efficiency (PEE) and quantum yield (φ) were also reached. The mechanism was discussed in our study.

Photothermally triggered fast responding hydrogels incorporating a hydrophobic moiety for light-controlled microvalves.

Iron oxide nanoparticles dispersed within a thermally responsive poly(N-isopropylacrylamide) (PNIPAm) hydrogel matrix effectively convert the photo energy of visible light of modest intensity into thermal energy, providing the efficient means to trigger changes in volumetric swelling of hydrogels. However, long irradiation time (on the order of minutes) and modest volume change limit their applications that need fast response and/or large volume change. In this work, we found that the degree of volume change triggered by light could be maximized by adjusting the lower critical solution temperature (LCST) of the hydrogels. On the basis of the evidence in this investigation, we can develop highly responsive hydrogels that show rapid and significant light-induced volume change, which could be achieved by incorporating a hydrophobic N,N-diethylacrylamide moiety in the PNIPAm network. This enhanced responsiveness led to the successful application of this material in a remote-controllable microvalve for microfluidic devices operated by light illumination within a few seconds.

Monochromatic Infrared Photo Energy versus Low Level Laser Therapy in Patients with Knee Osteoarthritis.

Knee osteoarthritis (KO) is the most common joint disease for which there is no optimal treatment. Monochromatic infrared photo energy (MIPE) is a relatively new light modality used to reduce pain and increase circulation. Low Level Laser Therapy (LLLT) is another light modality used to reduce pain in KO. The aim of this study was to compare the effects of the MIPE and LLLT in improving pain and function in KO. Sixty participants with KO completed the program and were randomly assigned into two groups. Group 1 (experimental, n=30) received MIPE and exercises. Group 2 (control, n=30) received LLLT and exercises. Both groups received two visits per week for six weeks. Outcome included pain intensity measured on a visual analogue scale and physical function measured with the lower extremity functional scale, before and after the 12 therapy sessions (6 weeks after the start of the intervention). There were statistically significant improvements in pain intensity and lower extremity functional scale scores (p<0.05) in each group. However, no significant differences were recorded between the groups (p>0.05). Therefore, MIPE and LLLT reduce pain and improve function in KO; however, there are no differences between the two modalities in reducing pain and increasing physical function in KO.

Enhanced Energy Harvesting Scheme Utilizing Hierarchical Nanostructures

Solar energy is mainly a daytime energy source, a possible candidate for renewable energy. Energy harvesting from solar energy can be divided into two parts, namely energy harvesting from photo energy (photo-solar) and energy harvesting thermal heating from solar energy (thermal-solar). The photo-solar means that the energy harvesting is based on collection of photo energy collected by solar cell while the thermal-solar means storage of the solar energy as thermal energy by solar-thermal power plant. In this talk, hierarchical nanostructures were used to enhance the energy harvesting based on photo-solar and thermal-solar in my group. In the first part of my talk, I will report fabrication of a large area Cu(In,Ga)Se2 nanotip arrays (CIGS NTRs) by using one step Ar+ milling process without template. By controlling milling time and incident angles, the length of CIGS NTRs with adjustable tilting orientations can be precisely controlled. The CIGS NTRs have very low reflectance < 0.1 % at incident wavelengths between 300 nm to 1200 nm. Open circuit voltage and short circuit current of CIGS NTRs solar cell were measured to be ~390 mV and ~22.56 mA/cm2, yielding the filling factor and the efficiency of 59 % and 5.2 %, respectively. In contrast to CIGS thin film solar cell with efficiency of 3.2 %, the nanostructured CIGS NTRs can have efficiency enhancement of ~160 % due to the higher light absorption ability because of the nanostructure. In the secondary part of my talk, an enhanced heat capacity of modified HITEC molten salt by doping of metal NPs will be reported. We encapsulate the Tin alloy into Sn/SiOx core-shell NPs to prevent mixture with salt when operation temperature is higher than the melting point of Tin. The SiOx shell layer can protect the Sn NPs to be oxidized and maintains a melted status during the heat cycles, providing a stable leant heat value of 28.36 J/g. Besides, effective heat capacity of HITEC salt with Sn/SiOx core-shell NPs can be enhanced to be 30 % a mixture percentage of 5 wt%. The merits of this approach show a low-cost and easy way to enhance the thermal properties of current molten salt without complicated manufacturing.

A Randomized Controlled Trial of Acupuncture for Chronic Low Back Pain

The Journal of Alternative and Complementary MedicineVol. 20, No. 5 Clinical ResearchA Randomized Controlled Trial of Acupuncture for Chronic Low Back PainHamidreza Bahrami-Taghanaki, Ying Liu, Hoda Azizi, Ali Khoursand-Vakilzadeh, Habibollah Esmaily, Abdollah Bahrami, and Bai Xiao ZhaoHamidreza Bahrami-TaghanakiSearch for more papers by this author, Ying LiuSearch for more papers by this author, Hoda AziziSearch for more papers by this author, Ali Khoursand-VakilzadehSearch for more papers by this author, Habibollah EsmailySearch for more papers by this author, Abdollah BahramiSearch for more papers by this author, and Bai Xiao ZhaoSearch for more papers by this authorPublished Online:7 May 2014https://doi.org/10.1089/acm.2014.5101.abstractAboutSectionsView articleView Full TextPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail View article"A Randomized Controlled Trial of Acupuncture for Chronic Low Back Pain." The Journal of Alternative and Complementary Medicine, 20(5), p. A40FiguresReferencesRelatedDetailsCited byAdditive effects of acupuncture in alleviating anxiety: A double-blind, three-arm, randomized clinical trialComplementary Therapies in Clinical Practice, Vol. 45Acupuncture Treatment for Pain: Clinical and Laboratory Research29 May 2019Monochromatic Infrared Photo Energy Versus Low Level Laser Therapy in Chronic Low Back Pain27 October 2015 | Journal of lasers in medical sciences, Vol. 6, No. 4 Volume 20Issue 5May 2014 InformationCopyright 2014, Mary Ann Liebert, Inc.To cite this article:Hamidreza Bahrami-Taghanaki, Ying Liu, Hoda Azizi, Ali Khoursand-Vakilzadeh, Habibollah Esmaily, Abdollah Bahrami, and Bai Xiao Zhao.A Randomized Controlled Trial of Acupuncture for Chronic Low Back Pain.The Journal of Alternative and Complementary Medicine.May 2014.A40-A40.http://doi.org/10.1089/acm.2014.5101.abstractPublished in Volume: 20 Issue 5: May 7, 2014PDF download

Utilization of Natural Porphyrin Thin Films as a Photosensitizer for Photodetectors

In this study, photodetectors were assembled using natural porphyrin as a sensitizer, and their energy gap properties were investigated. The natural porphyrin thin film layered devices used in the experiments were deposited by spin coating on a patterned electrode of Cu printed circuit board substrates. The photo sensitive characteristics were measured both with and without illumination by white light. The photo sensitive effect increased with the number of layers. A maximum current of 2.6 nA was obtained when the films consisted of three layers and the current increased to 7.9 nA for seven layers. To clarify the results, the dependence of the number of layers on the energy gap was evaluated. The experiment results showed that the energy gap decreased linearly with increasing number of layers. The mutual combination of the photo sensitive effect and energy gap indicated that it is possible to apply natural porphyrin as a sensitizer for photodetector applications.

Investigation of the third-order nonlinear optical susceptibilities associated with intersubband transitions in CdSe/ZnS/SiO2 core/shell/shell quantum dot

Using the one band effective mass approximation model we computed the optical properties for the spherical shape CdSe/ZnS/SiO2 core/shell/shell quantum dot (CSSQD). We calculated the charge carrier energies and corresponding wave functions. We investigated the radiative recombination lifetime of CSSQD nanocrystal, we found that the radiative lifetime is increased when we added the SiO2 layer for the CdSe/ZnS core/shell quantum dots. Then we calculated the nonlinear susceptibilities associated with intersubband transitions in the conduction band for CdSe/ZnS/SiO2 spherical CSSQD, and the third-order susceptibilities for quadratic electro–optic effects as a function of the core, shell radii and pump photo energy involving the position of energy levels also have been analyzed. The results show that the dot size plays a fundamental role in determining the nonlinear optical properties of quantum dots. Indeed, we see that the variation of the size of CdSe core has a more remarkable effect on nonlinear susceptibilities than the change in the thickness of the ZnS layer, and the variation of the SiO2 layer thickness has a negligible effect.

Enhanced photocatalytic degradation of methylene blue on multiwalled carbon nanotubes–TiO2

A visible-light photocatalyst of multiwalled carbon nanotubes decorated with TiO2 nanoparticles (MWCNT/TiO2) was synthesized by a two-step method, in which TiO2 was first mounted on MWCNT surfaces by hydrolysis of tetrabutyl titanate and further crystallized into anatase nanocrystal in a vacuum furnace at 500°C. The photocatalytic degradation of methylene blue over the ultraviolet (UV) and visible-light spectrum regions was investigated. The MWCNT/TiO2 was able to absorb a high amount of photo energy in the visible-light region, driving effectively photochemical degradation reactions. There were more OH radicals produced by the MWCNT/TiO2 (1:3) than by pure TiO2 under UV and visible-light irradiation. In the photodegradation of methylene blue, as a model reaction, a signification enhancement in the reaction rate was observed with the MWCNT/TiO2 (1:3), compared to bare TiO2 and the physical mixture of MWCNTs and TiO2. MWCNTs can improve the photocatalytic activity of TiO2 in two aspects, namely e− transportation and adsorption. This work provides new insight into the fabrication of MWCNT/TiO2 as a high performance visible-light photocatalyst and facilitates its application in photocatalytic degradation of organic compounds.

Preparation of Cu2ZnSnS4 film by sulfurizing solution deposited precursors

Cu2ZnSnS4 (CZTS) film was obtained by sulfurizing (Cu, Sn)S/ZnS structured precursor that was prepared by a combination of the successive ionic layer adsorption and reaction method and the chemical bath deposition method. Pure Cu2ZnSnS4 phase was obtained when the precursor was annealed at 500°C for 2h. The structure, composition, morphology and optical properties of the CZTS film were studied. The results show that the CZTS film has a relatively compact morphology, and the composition of the film is close to the stoichiometric ratio of Cu2ZnSnS4. The film presents a large optical absorption coefficient (larger than 104cm−1 when the photo energy is beyond 1.47eV). The optical band-gap of the film is around 1.56eV. This method is considered a potential way to prepare high quality CZTS film.

Monochromatic Infrared Photo Energy in Diabetic Peripheral Neuropathy

Diabetes is a very common cause of peripheral neuropathy, and there is no optimal intervention universally accepted by clinicians. Monochromatic infrared photo energy is a relatively new modality used in the United States for reducing pain and increasing circulation. This study investigated the effects of monochromatic infrared photo energy on reducing pain, improving sensation, and increasing balance in patients with diabetic peripheral neuropathy. Thirty-five patients with diabetic peripheral neuropathy completed the program and were randomly assigned into two groups. Group 1 (experimental, ) received monochromatic infrared photo energy, therapeutic exercises, and balance training. Group 2 (control, ) received therapeutic exercises and balance training. Both groups received three treatment sessions per week for 4 weeks. Outcome included pain intensity measured on a visual analogue scale, sensation measured with the Semmes-Weinstein monofilament 5.07, and balance measured with the Berg score, before and after the 12 therapy sessions (1 month after the start of the intervention). Analysis of covariance tests revealed statistically significant improvements, specifically, , .014, and .0001, for pain, sensation, and balance, respectively, in the experimental group. Within the limitations of this study, monochromatic infrared photo energy may play a role in treating diabetic peripheral neuropathy by reducing pain, improving sensation, and increasing balance.

온칩 다이오드를 이용한 빛에너지 하베스팅 회로 설계

본 논문에서는 CMOS 공정의 p-diff/n-well 다이오드만을 사용한 ISC(Integrated Solar Cell)를 이용하여 MPPT(Maximum Power Point Tracking) 제어 기능을 갖는 온칩 빛에너지 하베스팅 시스템을 제안하였다. MPPT 제어는 PV(Photovoltaic) 셀의 개방전압과 MPP(Maximum Power Point) 전압간의 비례관계를 이용하여, 작은 pilot PV 셀로 하여금 main PV 셀의 MPP를 실시간 추적할 수 있도록 설계하였다. 모의실험 결과 설계된 회로는 MPPT 제어기능을 적용했을 때 부하가 큰 경우에도 MPP 근처의 전압을 부하에 공급함으로써 부하에 연결된 회로가 정상적으로 동작하는 것을 확인하였다. 제안된 회로는 0.18um CMOS 공정으로 설계하였으며, main PV 셀과 pilot PV 셀의 면적은 각각 <TEX>$8mm^2$</TEX>와 <TEX>$0.4mm^2$</TEX>이다. In this paper an on-chip photo energy harvesting system with MPPT(Maximum Power Point Tracking) control is proposed. The ISC(Integrated Solar Cell) is implemented using p-diff/n-well diodes available in CMOS processes. MPPT control is implemented using the linear relationship between the open-circuit voltage of a PV(Photovoltaic) cell and its MPP(Maximum Power Point) voltage such that a small pilot PV cell can track the MPP of a main PV cell in real time. Simulation results show that the designed circuit with the MPPT control delivers the MPP voltage to load even though the load is heavy such that the load circuit can operate properly. The proposed circuit is designed in 0.18um CMOS process. The designed main PV cell and pilot PV cell occupy <TEX>$8mm^2$</TEX> and <TEX>$0.4mm^2$</TEX> respectively.

Fabrication of TiO2 nanotubes with extended periodical morphology by alternating-current anodization

Highly uniform TiO2 nanotube arrays with regular periodical sidewall morphology were fabricated by both alternating-voltage (AV) and alternating-current (AC) anodization methods. It was revealed that the AC anodization provided a better control to the sidewall morphology than the AV anodization. Various bamboo-shaped nanotube arrays were prepared by using AC anodization with different current functions. Dye-sensitized solar cells (DSSCs) fabricated using different TiO2 nanotube arrays showed that the AC anodization with square-wave driving current gave the highest photo energy conversion efficiency.

Monochromatic Infrared Photo Energy in Diabetic Peripheral Neuropathy

Diabetes is a very common cause of peripheral neuropathy, and there is no optimal intervention universally accepted by clinicians. Monochromatic infrared photo energy is a relatively new modality used in the United States for reducing pain and increasing circulation. This study investigated the effects of monochromatic infrared photo energy on reducing pain, improving sensation, and increasing balance in patients with diabetic peripheral neuropathy. Thirty-five patients with diabetic peripheral neuropathy completed the program and were randomly assigned into two groups. Group 1 (experimental, 𝑛=18) received monochromatic infrared photo energy, therapeutic exercises, and balance training. Group 2 (control, 𝑛=17) received therapeutic exercises and balance training. Both groups received three treatment sessions per week for 4 weeks. Outcome included pain intensity measured on a visual analogue scale, sensation measured with the Semmes-Weinstein monofilament 5.07, and balance measured with the Berg score, before and after the 12 therapy sessions (1 month after the start of the intervention). Analysis of covariance tests revealed statistically significant improvements, specifically, 𝑃=.01, .014, and .0001, for pain, sensation, and balance, respectively, in the experimental group. Within the limitations of this study, monochromatic infrared photo energy may play a role in treating diabetic peripheral neuropathy by reducing pain, improving sensation, and increasing balance.

Enhanced photocatalytic degradation of methylene blue under visible irradiation on graphene@TiO2 dyade structure

Electron–hole recombination limits the efficiency of TiO2. We have investigated the efficacy with which the graphene@TiO2 “dyade”-like structure reduced charge recombination and enhanced reactivity. A visible-light photocatalysis of graphene@TiO2 “dyade”-like structure was synthesized, and photocatalytic degradation of organic compounds over the UV and visible-light spectrum regions was investigated. The graphene@TiO2 had anatase phase and was able to absorb a high amount of photo energy in the visible-light region, driving effectively photochemical degradation reactions. There were more OH radicals produced by the graphene@TiO2 (1:3) than by pure TiO2 under UV and visible-light irradiation. Graphene can enhance the photocatalytic activity of TiO2 in two aspects, namely, e− transportation and adsorption. This work provides new insight into the fabrication of graphene@TiO2 as a high performance visible-light photocatalyst and facilitates its application in photocatalytic degradation of organic compounds.

Effect of Gas Pressure on Optical Properties of Nanocrystalline Diamond Films Deposited on SiC Substrates

With use of electron-assisted chemical vapor deposition technology, nanocrystalline diamond films were deposited on SiC ceramics substrates at various gas pressure ( 0.5 ~ 2 kPa ). Effect of the gas pressure on optical properties of the nanocrystalline diamond films was studied. Raman scattering spectra were measured. Photoluminescence spectra were investigated in the range of 420 ~ 680 nm. Spectroscopic ellipsometry were analyzed from the near IR to the UV region ( 1.5 ~ 5.0 eV ). Results show that, when the gas pressure increased from 0.5 to 2 kPa, Raman scattering intensity of diamond increase and D/G ratio decrease; when the gas pressure was 0.5kPa and 2kPa, there is not any PL peak, however, there is a stronger PL peak at 485 nm when the gas pressure was 1kPa; extinctive coefficient k for the nanocrystalline diamond films deposited at 1kPa increase obviously with increase of photo energy.

Nitrogen-Doped Anatase Nanofibers Decorated with Noble Metal Nanoparticles for Photocatalytic Production of Hydrogen

We report the synthesis of N-doped TiO(2) nanofibers and high photocatalytic efficiency in generating hydrogen from ethanol-water mixtures under UV-A and UV-B irradiation. Titanate nanofibers synthesized by hydrothermal method are annealed in air and/or ammonia to achieve N-doped anatase fibers. Depending on the synthesis route, either interstitial N atoms or new N-Ti bonds appear in the lattice, resulting in slight lattice expansion as shown by XPS and HR-TEM analysis, respectively. These nanofibers were then used as support for Pd and Pt nanoparticles deposited with wet impregnation followed by calcination and reduction. In the hydrogen generation tests, the N-doped samples were clearly outperforming their undoped counterparts, showing remarkable efficiency not only under UV-B but also with UV-A illumination. When 100 mg of catalyst (N-doped TiO(2) nanofiber decorated with Pt nanoparticles) was applied to 1 L of water-ethanol mixture, the H(2) evolution rates were as high as 700 μmol/h (UV-A) and 2250 μmol/h (UV-B) corresponding to photo energy conversion percentages of ∼3.6 and ∼12.3%, respectively.

Study of the Interface Properties of TiO&lt;sub&gt;2&lt;/sub&gt;/SiO&lt;sub&gt;2&lt;/sub&gt;/SiC by Photocapacitance

We have investigated the annealing of fixed oxide charge and interfacial traps in MISiC strucures by means of the photo capacitance voltage technique at temperatures up to 500°C. Elevated temperature measurements show reduced hysteresis and reduced fixed oxide charge at the interface. The photo capacitance technique shows a real-time measurement at elevated temperatures, in which electrons are populated by photo energy, in a 4H-SiC MIS structure. We also confirm the reduction of fixed oxide charge at the interface by means of high temperature post deposition annealing, which occurs during the high temperature measurements.

多层栅介质层有机薄膜晶体管的存储与光响应特性

The organic thin film transistors(OTFTs) based on multi-layer gate dielectric were presented without vacuum breaks.As a result,the OTFTs show multi-functional properties,such as electric-switching,memory,and photosensitive.The memory effect was attributed to the structure of OTFTs,i.e.the utilization of the separated CaF2 nanoparticle islands acting as the charge trapping centers.The photo-responses included two different types of fast response and slow response,and are,respectively,originated from the generation of mobile carriers by the absorption of photo energy higher than the band gap energy of semiconductor and the tapped and released of photo-induced electrons by the traps in the dielectric at the electrical field modulation.

Solar photo energy technologies for electric power consumers

Solar photo energy technologies are examined for electric power consumers, and the prospects for their development are considered.