Browsing by Author "Lin, Wei-Hao"

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A facile green antisolvent approach to Cu2+-doped ZnO nanocrystals with visible-light-responsive photoactivities
(2014-08-07)
Lu, Yi-Hsuan
;
Lin, Wei-Hao
;
Yang, Chao-Yao
;
Chiu, Yi-Hsuan
;
Pu, Ying-Chih
An environmentally benign antisolvent method has been developed to prepare Cu2+-doped ZnO nanocrystals with controllable dopant concentrations. A room temperature ionic liquid, known as a deep eutectic solvent (DES), was used as the solvent to dissolve ZnO powders. Upon the introduction of the ZnO-containing DES into a bad solvent which shows no solvation to ZnO, ZnO was precipitated and grown due to the dramatic decrease of solubility. By adding Cu2+ ions to the bad solvent, the growth of ZnO from the antisolvent process was accompanied by Cu2+ introduction, resulting in the formation of Cu2+-doped ZnO nanocrystals. The as-prepared Cu2+-doped ZnO showed an additional absorption band in the visible range (400-800 nm), which conduced to an improvement in the overall photon harvesting efficiency. Time-resolved photoluminescence spectra, together with the photovoltage information, suggested that the doped Cu2+ may otherwise trap photoexcited electrons during the charge transfer process, inevitably depressing the photoconversion efficiency. The photoactivity of Cu2+-doped ZnO nanocrystals for photoelectrochemical water oxidation was effectively enhanced in the visible region, which achieved the highest at 2.0 at% of Cu2+. A further increase in the Cu2+ concentration however led to a decrease in the photocatalytic performance, which was ascribed to the significant carrier trapping caused by the increased states given by excessive Cu2+. The photocurrent action spectra illustrated that the enhanced photoactivity of the Cu2+-doped ZnO nanocrystals was mainly due to the improved visible photon harvesting achieved by Cu2+ doping. These results may facilitate the use of transition metal ion-doped ZnO in other photoconversion applications, such as ZnO based dye-sensitized solar cells and magnetism-assisted photocatalytic systems.
A facile green antisolvent approach to Cu2+-doped ZnO nanocrystals with visible-light-responsive photoactivities
(2014-08-07)
Lu, Yi-Hsuan
;
Lin, Wei-Hao
;
Yang, Chao-Yao
;
Chiu, Yi-Hsuan
;
Pu, Ying-Chih
An environmentally benign antisolvent method has been developed to prepare Cu2+-doped ZnO nanocrystals with controllable dopant concentrations. A room temperature ionic liquid, known as a deep eutectic solvent (DES), was used as the solvent to dissolve ZnO powders. Upon the introduction of the ZnO-containing DES into a bad solvent which shows no solvation to ZnO, ZnO was precipitated and grown due to the dramatic decrease of solubility. By adding Cu2+ ions to the bad solvent, the growth of ZnO from the antisolvent process was accompanied by Cu2+ introduction, resulting in the formation of Cu2+-doped ZnO nanocrystals. The as-prepared Cu2+-doped ZnO showed an additional absorption band in the visible range (400-800 nm), which conduced to an improvement in the overall photon harvesting efficiency. Time-resolved photoluminescence spectra, together with the photovoltage information, suggested that the doped Cu2+ may otherwise trap photoexcited electrons during the charge transfer process, inevitably depressing the photoconversion efficiency. The photoactivity of Cu2+-doped ZnO nanocrystals for photoelectrochemical water oxidation was effectively enhanced in the visible region, which achieved the highest at 2.0 at% of Cu2+. A further increase in the Cu2+ concentration however led to a decrease in the photocatalytic performance, which was ascribed to the significant carrier trapping caused by the increased states given by excessive Cu2+. The photocurrent action spectra illustrated that the enhanced photoactivity of the Cu2+-doped ZnO nanocrystals was mainly due to the improved visible photon harvesting achieved by Cu2+ doping. These results may facilitate the use of transition metal ion-doped ZnO in other photoconversion applications, such as ZnO based dye-sensitized solar cells and magnetism-assisted photocatalytic systems.
A Facile Seed-Mediated Route to Au Nanoplates for SERS Application
(2011)
Lin, Wei-Hao
;
Hsu, Yung-Jung
;
材料科學與工程學系
;
Department of Materials Science and Engineering
We have successfully synthesized Au nanoplates using a seed-mediated approach. Without the size-selection process, the yield of nanoplates in the as-obtained product was as high as 80 %. The nanoplate samples were characterized with TEM, SAED, XRD, UV-VIS-NIR and SERS spectroscopy. The results of SERS analyses demonstrate the potential of the anisotropicaily-shaped Au nanoplates as an active platform for Raman-sensitive analyte molecules.
Au nanoplates as robust, recyclable SERS substrates for ultrasensitive chemical sensing
(2014-03-15)
Lin, Wei-Hao
;
Lu, Yi-Hsuan
;
Hsu, Yung-Jung
;
材料科學與工程學系
;
Department of Materials Science and Engineering
With the structural advantages of being sharp and straight, Au nanoplates may work as a promising surface-enhanced Raman scattering (SERS) platform for detection of Raman-sensitive analytes. However, the utilization of Au nanoplates as realistic SERS substrates is still not widely investigated, especially in the practical detection of environmentally persistent pollutants. This work delivers the first successful demonstration of using Au nanoplate platform in practical SERS sensing toward a typical polycyclic aromatic hydrocarbons pollutant of pyrene. The samples were prepared using an environmentally benign seed-mediated growth approach without the post-purification treatment. It was found that Au nanoplates exhibited significantly enhanced SERS activities (enhancement factor = 7.30 x 10(7)) and achieved an extremely low detection limit (5 x 10(-10) M) toward pyrene molecules. Furthermore, the SERS activity of Au nanoplates can be fully recovered after repeatedly used and recycled in pyrene detection. These results manifest that the present Au nanoplates can serve as robust, recyclable SERS substrates that allow rapid detection of trace levels of analytes with a high degree of sensitivity and stability. The findings from this work may facilitate the use of Au nanoplate SERS substrates in more realistic applications such as biomolecule sensing and environmental monitoring. (C) 2013 Elsevier Inc. All rights reserved.
Au-Cd1-xZnxS core-alloyed shell nanocrystals: boosting the interfacial charge dynamics by adjusting the shell composition
(2018-09-28)
Pu, Ying-Chih
;
Chen, Wei-Ta
;
Fang, Mei-Jing
;
Chen, Yu-Lin
;
Tsai, Kai-An
Au-Cd1-xZnxS core-shell nanocrystals (NCs) with controllable shell compositions (from x = 0 to x = 0.37) were synthesized by using the hot-injection method. By increasing the mole fraction of ZnS in the Cd1-xZnxS shell, the conduction band of Cd1-xZnxS can be cathodically shifted to cause an increase of energy difference between the conduction band level of the Cd1-xZnxS shell and the Fermi level of the Au core, thereby enlarging the driving force of interfacial electron transfer to enhance the photoelectrochemical (PEC) efficiency. The interfacial charge dynamics of the samples were examined by time-resolved photoluminescence (TRPL) spectroscopy. The results showed that the interfacial electron transfer rate constant (k(et)) from the Cd1-xZnxS shell to the Au core was increased by 2 orders of magnitude, from 2.41 x 10(7) to 4.91 x 10(9) s(-1) as the mole fraction of ZnS increased from 0 to 0.37. Furthermore, PEC characterization, including Mott-Schottky analysis and photovoltage decay measurements, illustrated that gradually introducing ZnS into the shell composition of Au-Cd1-xZnxS NCs can modify the band structure and enhance the effectiveness of interfacial ET for advancing the PEC properties. The practical use of Au-Cd1-xZnxS NCs in PEC methanol oxidation was also demonstrated, revealing their promising potential as viable photoelectrodes for various PEC applications. The present study delivers an alternative approach of modulating the interfacial ET dynamics of core-shell MSNs by means of shell composition adjustment. The illustrations provide an empirical guideline to the intelligent design of core-shell metal-semiconductor nanoheterostructures (MSNs) for the desired PEC applications.
Cathodic deposition of TiO2 thin films with supercritical CO2 emulsified electrolyte
(2013-08-01)
Chang, Tso-Fu Mark
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Lin, Wei-Hao
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Hsu, Yung-Jung
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Chen, Chun-Yi
;
Sato, Tatsuo
TiO2 thin films were fabricated by cathodic deposition with a supercritical CO2 (sc-CO2) emulsified TiCl3 + NaNO3 electrolyte. Morphology and average grain size were evaluated by SEM, TEM and XRD. SEM micrographs showed that the TiO2 films fabricated by TiCl3 + NaNO3 electrolyte were porous, and the films were composed of particles and aggregates of the particles. Also, size of the particles increased when the sc-CO2 emulsified electrolyte was used. Average grain size of the TiO2 films was calculated using Scherrer equation. The average grain size was found to increase when the sc-CO2 emulsified electrolyte was used. In addition, both particle sizes observed from SEM and average grain size calculated using Scherrer equation were found to increase when pressure was increased from atmospheric pressure to 20 MPa. (c) 2013 Elsevier B.V. All rights reserved.
Conjugated Polymer/Nanocrystal Nanocomposites for Renewable Energy Applications in Photovoltaics and Photocatalysis
(2014-11-26)
Su, Yu-Wei
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Lin, Wei-Hao
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Hsu, Yung-Jung
;
Wei, Kung-Hwa
;
材料科學與工程學系
Conjugated polymer/nanocrystal composites have attracted much attention for use in renewable energy applications because of their versatile and synergistic optical and electronic properties. Upon absorbing photons, charge separation occurs in the nanocrystals, generating electrons and holes for photocurrent flow or reduction/oxidation (redox) reactions under proper conditions. Incorporating these nanocrystals into conjugated polymers can complement the visible light absorption range of the polymers for photovoltaics applications or allow the polymers to sensitize or immobilize the nanocrystals for photocatalysis. Here, the current developments of conjugated polymer/nanocrystal nanocomposites for bulk heterojunction-type photovoltaics incorporating Cd- and Pb-based nanocrystals or quantum dots are reviewed. The effects of manipulating the organic ligands and the concentration of the nanocrystal precursor, critical factors that affect the shape and aggregation of the nanocrystals, are also discussed. In the conclusion, the mechanisms through which conjugated polymers can sensitize semiconductor nanocrystals (TiO2, ZnO) to ensure efficient charge separation, as well as how they can support immobilized nanocrystals for use in photocatalysis, are addressed.
Effects of Fluorinated Surfactant in Cathodic Deposition of TiO2 Films with Supercritical CO2 Emulsified Electrolyte
(2014)
Chang, Tso-Fu Mark
;
Lin, Wei-Hao
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Hsu, Yung-Jung
;
Sato, Tatsuo
;
Sone, Masato
Effect of a fluorinated surfactant, F(CF(CF3)CF2O)(3)CF(CF3)COO(CH2CH2O)CH3, in pore structure and grain size of the TiO2 films deposited cathodically was studied. Increase in pore size and decrease in grain size were observed when the fluorinated surfactant was used. When supercritical CO2 was introduced into the system, synergetic effect on increasing the pore size was observed. Also, grain coarsening was observed for the films deposited with supercritical CO2. Therefore, the fluorinated surfactant combining with supercritical CO2 demonstrated the ability to control morphology and grain size of the deposited TiO2 films at the same time. (C) 2014 The Electrochemical Society. All rights reserved.
Effects of Pressure in Cathodic Deposition of TiO2 and SnO2 with Supercritical CO2 Emulsified Electrolyte
(2016-08-01)
Lin, Wei-Hao
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Chen, Chun-Yi
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Chang, Tso-Fu Mark
;
Hsu, Yung-Jung
;
Sone, Masato
This study reports the effect of the high pressure on properties, especially the crystallinity, of the TiO2 and SnO2 films cathodically deposited in supercritical CO2 emulsified electrolyte. The as-deposited metal oxides are usually amorphous when cathodic deposition is applied. An additional heat treatment process is needed to have crystalline metal oxides. In this study, the TiO2 and SnO2 thin films cathodically deposited at elevated pressure showed an improvement in the crystallinity with an increase in the pressure using X-ray diffraction analysis. The high-resolution transmission electron microscopy and selected-area electron diffraction confirmed that the TiO2 deposited at 35 MPa had the anatase crystal structure. An enhancement in the charge carrier dynamics at the TiO2 electrode/electrolyte interface with an increase in the pressure was observed from the electrochemical impedance spectroscopy, which is a result of the improved crystallinity. The effect of the pressure on the crystallinity of the SnO2 was more obvious than that on the TiO2. Grain size of the SnO2 films estimated by the Scherrer equation was increased from 3.5 to 14.8 nm when the pressure was increased from 5 to 25 MPa. (C) 2016 Elsevier Ltd. All rights reserved.
First demonstration of rainbow photocatalysts using ternary Cd1-xZnxSe nanorods of varying compositions
(2014-04-22)
Nguyen, An T.
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Lin, Wei-Hao
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Lu, Yi-Hsuan
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Chiou, Yao-De
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Hsu, Yung-Jung
We demonstrated for the first time that the assembly of Cd1-xZnxSe nanorods (NRs) with five compositions (x= 0, 0.35, 0.54, 0.61,1) may absorb the whole visible spectrum in a gradient fashion for photoconversion applications. The samples were prepared by conducting cation exchange reactions on Ag2Se NRs with excess Cd2+ and Zn2+ ions. By modulating the molar ratio of Cd2+ to Zn2+ employed, the composition of the resulting Cd1-xZnxSe NRs can be delicately controlled. Because of the tunability of band edge with stoichiometry, Cd1-xZnxSe NRs of varying compositions absorbed light at different wavelength regions, which spanned almost the entire visible spectrum. As compared to the individual constituent NRs, the NRs assembly exhibited greatly improved photoactivity in photoelectrochemical water splitting as well as superior photocatalytic performance toward methylene blue degradation under white light illumination. This superiority emanates from the composition-gradient configuration that significantly improves the light harvesting efficiency by absorbing almost the whole visible spectrum of the incident white light. The full visible photon harvesting of the NRs assembly was validated by the photocurrent action spectrum which showed spectral accordance with the absorption spectrum. The recycling test manifests that the NRs assembly displayed substantially high stability during its use as photocatalyst. Furthermore, the result of performance evaluation under natural sunlight reveals that the present NRs assembly can be used as practical rainbow photocatalysts which may effectively harvest energy from sunlight. The demonstration from this work may facilitate the use of sophisticated assembly of semiconductor nanocrystals in relevant photoconversion processes where the effectiveness of photon harvesting is determinant. (C) 2014 Elsevier B.V. All rights reserved.
"Functional Connectivity During Phonemic and Semantic Verbal Fluency Test: A Multichannel Near Infrared Spectroscopy Study" (vol 22, pg 43, 2016)
(2019-11-01)
Huang, Chun-Jung
;
Chou, Po-Han
;
Lin, Wei-Hao
;
Sun, Chia-Wei
;
交大名義發表
Metal-Particle-Decorated ZnO Nanocrystals: Photocatalysis and Charge Dynamics
(2016-12-07)
Lin, Wei-Hao
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Chiu, Yi-Hsuan
;
Shao, Pao-Wen
;
Hsu, Yung-Jung
;
材料科學與工程學系
Understanding of charge transfer processes is determinant to the performance optimization for semiconductor photocatalysts. As a representative model of composite photocatalysts, metal-particle-decorated ZnO has been widely employed for a great deal of photocatalytic applications; however, the dependence of charge carrier dynamics on the metal content and metal composition and their correlation with the photocatalytic properties have seldom been reported. Here, the interfacial charge dynamics for metal-decorated ZnO nanocrystals were investigated and their correspondence with the photocatalytic properties was evaluated. The samples were prepared with a delicate antisolvent approach, in which ZnO nanocrystals were grown along with metal particle decoration in a deep eutectic solvent. By modulating the experimental conditions, the metal content (from 0.6 to 2.3 at%) and metal composition (including Ag, Au, and Pd) in the resulting metal-decorated ZnO could be readily controlled. Time-resolved photoluminescence spectra showed that an optimal Au content of 1.3 at% could effectuate the largest electron transfer rate constant for Au-decorated ZnO nanocrystals, in conformity with the highest photocatalytic efficiency observed. The relevance of charge carrier dynamics to the metal composition was also inspected and realized in terms of the energy level difference between ZnO and metal. Among the three metal-decorated ZnO samples tested, ZnO-Pd displayed the highest photocatalytic activity, fundamentally according with the largest electron transfer rate constant deduced in carrier dynamics measurements. The current work was the first study to present the correlations among charge carrier dynamics, metal content, metal composition, and the resultant photocatalytic properties for semiconductor/metal heterostructures. The findings not only helped to resolve the standing issues regarding the mechanistic foundation of photocatalysis but also shed light on the intelligent design of semiconductor/metal composite systems to consolidate their utility in photocatalytic fields.
Modulation of charge carrier dynamics of NaxH2-xTi3O7-Au-Cu2O Z-scheme nanoheterostructures through size effect
(2015-02-01)
Pu, Ying-Chih
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Lin, Wei-Hao
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Hsu, Yung-Jung
;
材料科學與工程學系
;
Department of Materials Science and Engineering
For the first time we presented the interfacial charge carrier dynamics for three-component semiconductor-metal-semiconductor Z-scheme nanoheterostructure system. The samples were prepared by selectively depositing a thin layer of Cu2O on the Au surface of Au nanoparticle-decorated NaxH2-xTi3O7 nanobelts (denoted as ST-Au NBs) using the photodeposition method. For ST-Au-Cu2O NB heterostructures, the embedded Au may act as carrier-transfer mediator to promote the electron transfer from the conduction band of ST to the valence band of Cu2O. This vectorial charge transfer would give rise to electron accumulation at Cu2O and hole concentration at ST, which achieved superior charge carrier separation over the two-component counterparts of ST-Au and ST-Cu2O. The quantum size effect was significant in the deposited Cu2O, which was exploited to tune the band structure of Cu2O, modulate the charge carrier dynamics of ST-Au-Cu2O NBs, and thereby enhance the resultant photocatalytic performance. Time-resolved photoluminescence spectra were measured to quantitatively analyze the electron transfer event between ST and Au for ST-Au-Cu2O NBs, which was found dependent on the Cu2O shell thickness. As the Cu2O thickness decreased, ST-Au-Cu2O NBs showed an increased electron-scavenging rate constant due to the increased driving force of electron transfer. The carrier dynamics results were fundamentally consistent with those of the performance evaluation in photocatalysis, in which ST-Au-Cu2O NBs exhibited enhanced photocatalytic efficiency as the Cu2O thickness decreased. Systematic understanding of the interfacial charge dynamics of Z-scheme mechanism shall pave the way for the realization of artificial photosynthesis by using heterogeneous photocatalysts, where the effectiveness of charge separation and the merit of high redox powers are determinant. (C) 2014 Elsevier B.V. All rights reserved.
Perceived Occupational Stress is associated with Decreased Cortical Activity of the Prefrontal Cortex: A Multichannel Near-infrared Spectroscopy Study
(2016-12-13)
Chou, Po-Han
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Lin, Wei-Hao
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Hung, Chao-An
;
Chang, Chiung-Chih
;
Li, Wan-Rung
Despite an increasing number of reports on the associations between chronic occupational stress and structural and functional changes of the brain, the underlying neural correlates of perceived occupational stress is still not clear. Perceived stress reflects the extents to which situations are appraised as stressful at a given point in one's life. Using near-infrared spectroscopy, we investigated the associations between perceived occupational stress and cortical activity over the bilateral frontotemporal regions during a verbal fluency test. Sixty-eight participants (17 men, 51 women), 20-62 years of age were recruited. Perceived occupational stress was measured using the Chinese version of Job Content Questionnaire, and the Chinese version of the Copenhagen Burnout Inventory. We found statistically significant negative associations between occupational burnout and brain cortical activity over the fronto-polar and dorsolateral prefrontal cortex during the VFT (r = -0.343 to -0.464). In conclusion, our research demonstrated a possible neural basis of perceived occupational stress that are distributed across the prefrontal cortex.
Reduced language lateralization in first episode schizophrenia: A near infrared spectroscopy study
(2017-08-01)
Chou, Po-Han
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Lin, Wei-Hao
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Li, Wang-Rung
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Huang, Chih-Mao
;
Sun, Chia-Wei
Background: Diminished functional lateralization in language-related areas is found in chronic schizophrenia (SZ). However, whether this reduced lateralization exists at the early stage of SZ remains unclear. The present study aimed to investigate language lateralization in first episode schizophrenia (FES) using near infrared spectroscopy (NIBS) during a letter version of verbal fluency test (VFT). Methods: A total of 28 FES patients and 33 healthy controls (HCs) underwent NIBS while performing a VFT. Six regions of interests (ROIs) were defined: the bilateral frontal-, inferior frontal gyrus (IFG), and temporal regions. Laterality index (LI) was calculated and compared between the two groups in ROIs. In addition, we investigated whether language lateralization was correlated with severity of clinical symptoms. Results: Across all ROIs, LI was significantly reduced in FES patients (p = 0.037) compared to controls in the IFG region. In addition, LI was not found to be correlated with VFT performance, the PANSS positive, negative or general psychopathology subscales. Conclusions: Our study demonstrated a diminution of leftward functional lateralization in the IFG during a VFT in FES patients. This is the first NIBS study to report reduced functional lateralization in patients at the early stage of schizophrenia.
Structural imperfections and attendant localized/itinerant ferromagnetism in ZnO nanoparticles
(2014-08-30)
Yang, Chao-Yao
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Lu, Yi-Hsuan
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Lin, Wei-Hao
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Lee, Min-Han
;
Hsu, Yung-Jung
Using synchrotron-based x-ray magnetic spectroscopy, we report a study focusing on the local symmetry of Cu-dopant and resultant structural imperfections in mediating Cu-doped ZnO nanoparticles\' ferromagnetism (FM). Prepared by an antisolvent method, Cu appeared to preferably populate on the basal plane of ZnO with a local symmetry of [CuO4]. This unique symmetry was antiferromagnetic in nature, while electronically and structurally coupled to surrounded oxygen vacancies (V-o) that yielded a localized FM, because of a strong dependency on the number/location of the [CuO4] symmetry. Surprisingly, the FM of undoped but oxygen-deficient ZnO appeared to be more itinerant and long-range, where V-o percolated the FM effectively and isotropically through oxygen\'s delocalized orbital. By adopting the approach of structural imperfection, this study clearly identifies V-o\'s (defect\'s) true characters in mediating the FM of magnetic semiconductors which has been thought of as a long-standing debate, and thus provides a different thinking about the traditional extrinsic ferromagnetic-tuning in the semiconductors. It even illuminates recent research concerning the intrinsic FM of low-dimensional systems that contain defects but non-magnetic elements.
Supercritical CO2-Assisted Electrochemical Deposition of ZnO Mesocrystals for Practical Photoelectrochemical Applications
(2013-12-05)
Lin, Wei-Hao
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Chang, Tso-Fu Mark
;
Lu, Yi-Hsuan
;
Sato, Tatsuo
;
Sone, Masato
We have successfully developed an effective supercritical CO2 (sc-CO2) emulsion-assisted electrochemical approach for cathodic deposition of ZnO mesocrystals. The sc-CO2 was introduced along with a nonionic surfactant in the process to form emulsified electrolyte, which significantly increased the supersaturation degree and promoted the molecular diffusion to affect the crystal growth of ZnO. The deposition involved the generation of primary nanocrystals with substantially high surface energy, followed by the preferred attachment of the primary nanocrystals along an energetically favorable orientation to form ZnO mesocrystals. The as-deposited ZnO mesocrystals exhibited remarkable optical properties at room temperature in terms of prominent near band-edge emission and substantially long exciton lifetime, attributable to the highly oriented crystallinity of mesocrystals that effectively suppressed the nonradiative charge recombination to extend the exciton decay dynamics. As compared to the structures prepared without the addition of surfactant or sc-CO2, ZnO mesocrystals from sc-CO2 emulsion displayed greatly improved photoactivity toward photoelectrochemical water oxidation, revealing their promising potential as photoanodes in relevant photoelectrochemical processes. The current study delivers the first demonstration of directly depositing ZnO mesocrystals on conductive substrates, which paves the way for utilization of mesocrystals as practical electrodes in technologically important energy conversion fields, such as electrochemical cells, photovoltaic devices, as well as photoelectrochemical water splitting, where the advantageous structural characteristics of mesocrystals, i.e., high crystallinity and abundant porosity, can be fully exploited.
The hydrobaric effect on cathodically deposited titanium dioxide photocatalyst
(2017-06-01)
Chang, Tso-Fu Mark
;
Lin, Wei-Hao
;
Chen, Chun-Yi
;
Hsu, Yung-Jung
;
Sone, Masato
The hydrobaric effect on photoactivity of titanium dioxide (TiO2) fabricated by cathodic deposition in an aqueous solution was evaluated in this study. When the applied pressure was increased to 35 MPa, the water-splitting performance was improved by almost fourfold of the performance of the TiO2 prepared at atmospheric pressure. The surface states effect was significant in the deposited TiO2, which was exploited to affect the charges recombination of TiO2, and thereby enhance the resultant photoelectrochemical water-splitting performance. The hydrobaric cathodic deposition could be extended to fabrication of other metal oxides to eliminate the negative influence from the high-temperature process.
Ultrafast formation of ZnO mesocrystals with excellent photocatalytic activities by a facile Tris-assisted antisolvent process
(2011)
Dong, Ji-Yao
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Lin, Wei-Hao
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Hsu, Yung-Jung
;
Wong, David Shan-Hill
;
Lu, Shih-Yuan
Ultrafast formation of ZnO mesocrystals was achieved with a facile, green, Tris-assisted, room temperature ionic liquid based antisolvent process. A deep eutectic solvent, formed by simply mixing and heating urea and choline chloride at 70 degrees C, served as the solvent for ZnO, whereas Tris-containing de-ionized water acted as the anti-solvent to trigger the ultrafast formation of ZnO mesocrystals at 70 degrees C. The product mesocrystals were mesoporous and near-single-crystalline with high specific surface areas, showing excellent photocatalytic activities toward photodegradation of methylene blue, comparable to that of a commercial photocatalyst, P-25 TiO(2), which is rarely achieved for pristine ZnO. The present approach is a general one and can be readily extended to production of mesocrystals of other functional metal oxides.