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Liu S, Sun H, Ang HM, Tade MO, Wang S. Integrated oxygen-doping and dye sensitization of graphitic carbon nitride for enhanced visible light photodegradation. J Colloid Interface Sci 2016; 476:193-199. [PMID: 27218807 DOI: 10.1016/j.jcis.2016.05.026] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 05/13/2016] [Accepted: 05/14/2016] [Indexed: 11/24/2022]
Abstract
Graphitic carbon nitride (GCN) is a promising metal-free photocatalyst while suffering from low charge mobility induced inefficient photocatalysis. In this work, oxygen doping was employed to enhance the photodegradation of organic pollutants in water on graphitic carbon nitride (GCNO) under visible light. For further absorption extension, four organic dyes (Eosin-Y, Perylene, Nile-red and Coumarin) were adopted to dye-sensitize the GCNO photocatalyst. It was found that O-doping can promote dye sensitization, which was dependent on the type of dyes and influenced the photodegradation efficiencies of methylene blue (MB) and phenol. Nile-red sensitized GCNO presented the best activity in MB degradation under λ>480nm irradiations while Eosin-Y showed the best sensitization performance for phenol degradation under λ>420nm light source. However, dye sensitization was not effective for enhanced pollutant degradation on GCN without O-doping. UV-vis diffuse reflectance spectra (UV-vis DRS), photoluminescence (PL) spectra, and photocurrent analyses were applied to investigate the mechanism of carriers' transfer, which indicated that dye molecules could inject extra electrons into GCNO energy band and the energy dislocation could suppress electron/hole recombination, enhancing photocatalytic performances.
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Affiliation(s)
- Shizhen Liu
- Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), Curtin University, GPO Box U1987, WA 6845, Australia
| | - Hongqi Sun
- Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), Curtin University, GPO Box U1987, WA 6845, Australia; School of Engineering, Edith Cowan University, Joondalup, WA 6027, Australia
| | - H M Ang
- Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), Curtin University, GPO Box U1987, WA 6845, Australia
| | - Moses O Tade
- Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), Curtin University, GPO Box U1987, WA 6845, Australia
| | - Shaobin Wang
- Department of Chemical Engineering and CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), Curtin University, GPO Box U1987, WA 6845, Australia.
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Asha Jhonsi M, Nithya C, Kathiravan A. Probing electron transfer dynamics of pyranine with reduced graphene oxide. Phys Chem Chem Phys 2014; 16:20878-86. [PMID: 25168852 DOI: 10.1039/c4cp03225j] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A stable reduced graphene oxide (rGO) was prepared and characterized by X-ray diffraction (XRD) and laser Raman spectroscopy. Steady state and time-resolved fluorescence quenching studies have been carried out to elucidate the process of electron transfer from excited pyranine (POH) into the rGO dispersion. POH adsorbed strongly on rGO dispersion with an apparent association constant of 33.4 (mg ml)(-1), and its fluorescence emission was quenched with an apparent association constant of 33.7 (mg ml)(-1). Picosecond lifetime measurements gave the rate constant for the electron transfer process from the excited singlet state of POH into the rGO dispersion as 8.8 × 10(9) s(-1). Laser flash photolysis studies demonstrated the formation of radicals for the evidence of electron transfer between POH and rGO.
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Affiliation(s)
- M Asha Jhonsi
- Department of Chemistry, B.S. Abdur Rahman University, Chennai - 600 048, Tamil Nadu, India.
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3
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Hess CM, Riley EA, Reid PJ. Dielectric dependence of single-molecule photoluminescence intermittency: nile red in poly(vinylidene fluoride). J Phys Chem B 2014; 118:8905-13. [PMID: 24995904 PMCID: PMC4372109 DOI: 10.1021/jp505874m] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
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The
dependence of single-molecule photoluminescence intermittency
(PI) or “blinking” on the local dielectric constant
(ε) is examined for nile red (NR) in thin films of poly(vinylidene
fluoride) (PVDF). In previous studies, variation of the local dielectric
constant was accomplished by studying luminophores in chemically and
structurally different hosts. In contrast, the NR/PVDF guest–host
pair allows for the investigation of PI as a function of ε while
keeping the chemical composition of both the luminophore and host
unchanged. The solvatochromic properties of NR are used to measure
the local ε, while fluctuations in NR emission intensity over
time provide a measure of the PI. PVDF is an ideal host for this study
because it provides submicron-sized dielectric domains that vary from
nonpolar (ε ≈ 2) to very polar (ε ≈ 70).
The results presented here demonstrate that the local dielectric environment
can have a pronounced effect on PI. We find that the NR emissive events
increase 5-fold with an increase in ε from 2.2 to 74. A complex
dependence on ε is also observed for NR nonemissive event durations,
initially increasing as ε increases from 2.2 to 3.4 but decreasing
in duration with further increase in ε. The variation in emissive
event durations with ε is reproduced using a photoinduced electron-transfer
model involving electron transfer from NR to PVDF. In addition, an
increase in NR photostability with an increase in ε is observed,
suggesting that the dielectric environment plays an important role
in defining the photostability of NR in PVDF.
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Affiliation(s)
- Chelsea M Hess
- Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195, United States
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Ehrenschwender T, Liang Y, Unterreiner AN, Wagenknecht HA, Wolf TJA. Fluorescence quenching over short range in a donor-DNA-acceptor system. Chemphyschem 2013; 14:1197-204. [PMID: 23532955 DOI: 10.1002/cphc.201200924] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 02/15/2013] [Indexed: 11/07/2022]
Abstract
A new donor-DNA-acceptor system has been synthesized containing Nile red-modified 2'-deoxyuridine as charge donor and 6-N,N-dimethylaminopyrene-modified 2'-deoxyuridine as acceptor to investigate the charge transfer in DNA duplexes using fluorescence spectroscopy and time-resolved femtosecond pump-probe techniques. Fluorescence quenching experiments revealed that the quenching efficiency of Nile red depends on two components: 1) the presence of a charge acceptor and 2) the number of intervening CG and AT base pairs between donor and acceptor. Surprisingly, the quenching efficiency of two base pairs (73% for CG and the same for AT) is higher than that for one base pair (68% for CG and 37% for AT), while at a separation of three base pairs less than 10% quenching is observed. A comparison with the results of time-resolved measurements revealed a correlation between quenching efficiency and the first ultrafast time constant suggesting that quenching proceeds via a charge transfer from the donor to the acceptor. All transients are satisfactorily described with two decays: a rapid charge transfer with 600 fs (∼10(12) s(-1)) that depends strongly and in a non-linear fashion on the distance between donor and acceptor, and a slower time constant of a few picoseconds (∼10(11) s(-1)) with weak distance dependence. A third time constant on a nanosecond time scale represents the fluorescence lifetime of the donor molecule. According to these results and time-dependent density functional theory (TDDFT) calculations a combination of single-step superexchange and multistep hopping mechanisms can be proposed for this short-range charge transfer. Furthermore, significantly less quenching efficiency and slower charge transfer rates at very short distances indicate that the direct interaction between donor and acceptor leads to a local structural distortion of DNA duplexes which may provide some uncertainty in identifying the charge transfer rates in short-range systems.
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Affiliation(s)
- Thomas Ehrenschwender
- Institute for Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
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5
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Hernández LI, Godin R, Bergkamp JJ, Llansola Portolés MJ, Sherman BD, Tomlin J, Kodis G, Méndez-Hernández DD, Bertolotti S, Chesta CA, Mariño-Ochoa E, Moore AL, Moore TA, Cosa G, Palacios RE. Spectral Characteristics and Photosensitization of TiO2 Nanoparticles in Reverse Micelles by Perylenes. J Phys Chem B 2012. [DOI: 10.1021/jp3086792] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Laura I. Hernández
- Departamento de Química,
Facultad de Ciencias Exactas Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río
Cuarto, Córdoba 5800, Argentina
| | - Robert Godin
- Department of Chemistry and
Center for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University, Otto Maass Chemistry Building, 801
Sherbrooke Street West, Montreal, QC, H3A 0B8, Canada
| | - Jesse J. Bergkamp
- Department of Chemistry and Biochemistry,
Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Manuel J. Llansola Portolés
- Department of Chemistry and Biochemistry,
Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Benjamin D. Sherman
- Department of Chemistry and Biochemistry,
Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - John Tomlin
- Department of Chemistry and Biochemistry,
Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Gerdenis Kodis
- Department of Chemistry and Biochemistry,
Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Dalvin D. Méndez-Hernández
- Department of Chemistry and Biochemistry,
Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Sonia Bertolotti
- Departamento de Química,
Facultad de Ciencias Exactas Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río
Cuarto, Córdoba 5800, Argentina
| | - Carlos A. Chesta
- Departamento de Química,
Facultad de Ciencias Exactas Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río
Cuarto, Córdoba 5800, Argentina
| | - Ernesto Mariño-Ochoa
- Department of Chemistry, Tecnológico de Monterrey, Campus Monterrey,
Monterrey, NL, 64849, México
| | - Ana L. Moore
- Department of Chemistry and Biochemistry,
Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Thomas A. Moore
- Department of Chemistry and Biochemistry,
Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Gonzalo Cosa
- Department of Chemistry and
Center for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University, Otto Maass Chemistry Building, 801
Sherbrooke Street West, Montreal, QC, H3A 0B8, Canada
| | - Rodrigo E. Palacios
- Departamento de Química,
Facultad de Ciencias Exactas Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río
Cuarto, Córdoba 5800, Argentina
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Silva R, Ferreira H, Azoia NG, Shimanovich U, Freddi G, Gedanken A, Cavaco-Paulo A. Insights on the Mechanism of Formation of Protein Microspheres in a Biphasic System. Mol Pharm 2012; 9:3079-88. [DOI: 10.1021/mp3001827] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Raquel Silva
- Department of Textile Engineering, University of Minho, Campus de Azurém, 4800-058,
Guimarães, Portugal
| | - Helena Ferreira
- Department of Textile Engineering, University of Minho, Campus de Azurém, 4800-058,
Guimarães, Portugal
| | - Nuno G. Azoia
- Department of Textile Engineering, University of Minho, Campus de Azurém, 4800-058,
Guimarães, Portugal
| | - Ulyana Shimanovich
- Laboratory for Nanomaterials, Centre for Advanced Materials and Nanotechnology, University of Bar-Ilan, Ramat-Gan 52900, Israel
| | - Giuliano Freddi
- Silk Research Institute, Via Giuseppe Colombo 83, 20133 Milan, Italy
| | - Aharon Gedanken
- Laboratory for Nanomaterials, Centre for Advanced Materials and Nanotechnology, University of Bar-Ilan, Ramat-Gan 52900, Israel
| | - Artur Cavaco-Paulo
- Department of Textile Engineering, University of Minho, Campus de Azurém, 4800-058,
Guimarães, Portugal
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