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1.
Dalton Trans ; 49(7): 2184-2189, 2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-31998903

RESUMO

Oxygen vacancies are recognized as the most prevalent defects in oxide materials. The effect of oxygen vacancies on the physicochemical properties of metal oxide semiconductors has attracted considerable attention in the photocatalysis field. But so far, the impact of oxygen vacancies on charge carrier transfer for photoelectrochemical water splitting has been unclear. In this work, TiO2 photoanodes with various oxygen vacancy concentrations were studied as metal oxide models to clarify the impact of oxygen vacancies on charge carrier transfer behaviors. The potential distribution and electrochemical impedance spectroscopy results indicate that the oxygen vacancies facilitate charge carrier diffusion in TiO2, but are disadvantageous for the charge carrier drift in the TiO2/electrolyte interface. The TiO2-400 photoanode with intermediate oxygen vacancy concentration exhibits the highest photocurrent density. It is expected that this work will provide reference to design and fabricate oxide semiconductors as photoanodes for higher charge carrier utilization in the field of solar-to-chemical energy conversion.

2.
Light Sci Appl ; 7: 97, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30510693

RESUMO

Macroscale fluorescence imaging is increasingly used to observe biological samples. However, it may suffer from spectral interferences that originate from ambient light or autofluorescence of the sample or its support. In this manuscript, we built a simple and inexpensive fluorescence macroscope, which has been used to evaluate the performance of Speed OPIOM (Out of Phase Imaging after Optical Modulation), which is a reference-free dynamic contrast protocol, to selectively image reversibly photoswitchable fluorophores as labels against detrimental autofluorescence and ambient light. By tuning the intensity and radial frequency of the modulated illumination to the Speed OPIOM resonance and adopting a phase-sensitive detection scheme that ensures noise rejection, we enhanced the sensitivity and the signal-to-noise ratio for fluorescence detection in blot assays by factors of 50 and 10, respectively, over direct fluorescence observation under constant illumination. Then, we overcame the strong autofluorescence of growth media that are currently used in microbiology and realized multiplexed fluorescence observation of colonies of spectrally similar fluorescent bacteria with a unique configuration of excitation and emission wavelengths. Finally, we easily discriminated fluorescent labels from the autofluorescent and reflective background in labeled leaves, even under the interference of incident light at intensities that are comparable to sunlight. The proposed approach is expected to find multiple applications, from biological assays to outdoor observations, in fluorescence macroimaging.

3.
ACS Omega ; 3(2): 1675-1683, 2018 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-31458487

RESUMO

Transition metal oxides, such as Co3O4, have attracted great attention for lithium-ion batteries (LIBs) due to their high theoretical capacity and satisfactory chemical stability. However, the slow kinetics of Li-ion and electron transport as well as poor cycling stability still largely restrains their applications. Here, we report the rational design of well-defined mesoporous ultrathin Co3O4 nanosheet arrays (NSAs) by topological transformation of layered double hydroxides nanosheet arrays (NSAs), which demonstrate significantly enhanced performance as anode for LIBs. The as-obtained Co3O4 NSAs with suitable thickness and abundant mesopores show excellent electrochemistry performance for LIBs, giving a high specific charge capacity of 2019.6 mAh g-1 at 0.1 A g-1, a good rate capability, and a remarkable cycling stability (1576.9 mAh g-1 after the 80th cycle), which is much superior to that of Co3O4 with thicker or thinner nanosheets as well as to that of the reported results. This facile strategy may be extended to the synthesis of other transition metal oxide NSAs, which can be potentially used in energy storage and conversion devices.

4.
Nat Commun ; 8(1): 2173, 2017 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-29242600

RESUMO

The Peer Review File associated with this Article was updated shortly after publication to redact from the authors' point-by-point response a description of unpublished work describing how Speed OPIOM may in future be used to facilitate discrimination between FRET and direct excitation.

5.
Nat Commun ; 8(1): 969, 2017 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-29042541

RESUMO

We present speed out-of-phase imaging after optical modulation (OPIOM), which exploits reversible photoswitchable fluorophores as fluorescent labels and combines optimized periodic illumination with phase-sensitive detection to specifically retrieve the label signal. Speed OPIOM can extract the fluorescence emission from a targeted label in the presence of spectrally interfering fluorophores and autofluorescence. Up to four fluorescent proteins exhibiting a similar green fluorescence have been distinguished in cells either sequentially or in parallel. Speed OPIOM is compatible with imaging biological processes in real time in live cells. Finally speed OPIOM is not limited to microscopy but is relevant for remote imaging as well, in particular, under ambient light. Thus, speed OPIOM has proved to enable fast and quantitative live microscopic and remote-multiplexed fluorescence imaging of biological samples while filtering out noise, interfering fluorophores, as well as ambient light.Generally, fluorescence imaging needs to be done in a dark environment using molecules with spectrally separated emissions. Here, Quérard et al. develop a protocol for high-speed imaging and remote sensing of spectrally overlapping reversible photoswitchable fluorophores in ambient light.


Assuntos
Microscopia de Fluorescência/métodos , Imagem Óptica/métodos , Brassicaceae/genética , Desenho de Equipamento , Corantes Fluorescentes/análise , Análise de Fourier , Proteínas de Fluorescência Verde/análise , Células HeLa , Humanos , Processamento de Imagem Assistida por Computador , Dispositivos Lab-On-A-Chip , Imagem Óptica/instrumentação , Plantas Geneticamente Modificadas , Proteínas Recombinantes/análise , Proteínas Recombinantes/genética
6.
Chemistry ; 23(34): 8142-8147, 2017 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-28485855

RESUMO

Selective oxidation of alcohols to aldehydes plays an important role in perfumery, pharmaceuticals, and agrochemicals industry. Different from traditional catalysis or photocatalytic process, here we report an effective photoelectrochemical (PEC) approach for selective anaerobic oxidation of alcohols accompanied with H2 production by means of solar energy. By using TiO2 nanowires modified with graphitic carbon layer as photoanode, benzyl alcohol (BA) has been oxidized to benzaldehyde with high efficiency and selectivity (>99 %) in aqueous media at room temperature, superior to individual electrocatalytic or photocatalytic processes. Moreover, this PEC synthesis method can be effectively extended to the oxidation of several other aryl alcohols to their corresponding aldehydes under mild conditions. The electron spin resonance (ESR) results indicate the formation of intermediate active oxygen (O2.- ) on the photoanode, which further reacts with alcohols to produce final aldehyde compounds.

7.
Opt Express ; 24(25): 28869-28876, 2016 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-27958552

RESUMO

We report a 1.3-µm dual-wavelength distributed feedback (DFB) photonic integrated chip with modulation bandwidth enhancement using integrated optical feedback section. The dual-wavelength DFB lasers were realized using the upper separate confinement heterostructure (SCH) selective area growth (SAG) approach. A modified butt-joint technique was also adopted to achieve high-quality active-passive interface and minimize unintentional intra-cavity optical feedbacks. The fabricated photonic chip exhibited stable single mode operations with a wavelength separation of 2.06 nm. The 3-dB modulation bandwidth was enhanced through the photon-photon resonance effect with f3dB > 17 GHz and open eyes up to 25 Gbit/s for both channels were also obtained. The design can also be scaled up to higher channel counts and higher data rate.

8.
Adv Mater ; 28(12): 2337-44, 2016 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-26808408

RESUMO

A honeycomb-like carbon-based network is obtained by in situ nucleation and directed growth of metal-organic framework (MOF) arrays on the surface of layered double hydroxide (LDH) nanoplatelets, followed by a subsequent pyrolysis process, which exhibits largely enhanced electrocatalytic ORR performances. A successful paradigm for the directed growth of highly oriented MOF arrays is demonstrated, with potential applications for energy storage and conversion.

9.
Chem Commun (Camb) ; 51(88): 15880-93, 2015 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-26459951

RESUMO

Two-dimensional (2D) materials have attracted increasing interest in electrochemical energy storage and conversion. As typical 2D materials, layered double hydroxides (LDHs) display large potential in this area due to the facile tunability of their composition, structure and morphology. Various preparation strategies, including in situ growth, electrodeposition and layer-by-layer (LBL) assembly, have been developed to directly modify electrodes by using LDH materials. Moreover, several composite materials based on LDHs and conductive matrices have also been rationally designed and employed in supercapacitors, batteries and electrocatalysis with largely enhanced performances. This feature article summarizes the latest developments in the design, preparation and evaluation of LDH materials toward electrochemical energy storage and conversion.

10.
Small ; 11(29): 3530-8, 2015 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-25788400

RESUMO

A sophisticated hierarchical nanoarray consisting of a conducting polymer (polypyrrole, PPy) core and layered double hydroxide (LDH) shell are synthesized via a facile two-step electrosynthesis method. The obtained PPy@LDH-based flexible all-solid-state supercapacitor meets the requirements of both high energy/power output and long-term endurance, which can be potentially used in highly-efficient and stable energy storage.

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