In-situ green synthesis of nitrogen-doped carbon dots for bioimaging and TiO2 nanoparticles@nitrogen-doped carbon composite for photocatalytic degradation of organic pollutants☆
Graphical abstract
Introduction
In recent years, the rapid development of industry and usage of hazardous organic dyes has increased environmental issues such as pollution including water pollution, air pollution and soil pollution, toxicity and carcinogenic effect all over the world [[1], [2], [3]]. To reduce the serious problem of these pollutants, increase the scientific efforts on this issues. Particularly, to avoid the water pollution, the major pollutants including hazardous organic dyes and heavy metals, should be removed from industrial waste-water before being released into the environment. In general, adsorption, chemical precipitation, sedimentation, ion-exchange, electrochemical and photocatalytic methods are used to reduce the water pollution [4]. Among them, photocatalytic degradation is an energy-saving, simple and highly efficient with the eco-friendly method and was used in the disposal of sewage [5,6]. Particularly, methylene blue (MB) is one of the colored organic compounds (organic dyes) and it is the most commonly used materials for dying cotton, silk, and wood. However, it can harm the living organism due to their toxicity, carcinogenicity and so forth. Hence, the removal of MB from industrial effluents is considered one of the environmental challenges in the recent years [[7], [8], [9], [10]]. Various semiconducting metal oxide nanoparticles as photocatalysts have been widely explored to the photocatalytic degradation of organic pollutants such as MB and so on [[11], [12], [13], [14], [15]]. Among the photocatalysts, titanium dioxide (TiO2) nanoparticles have great attention by the scientific research workers due to their high photosensitivity, stability, nontoxicity, chemical inertness, dispersion property, low cost, and availability in abundance [[16], [17], [18], [19], [20], [21]]. However, TiO2 nanoparticles have some limitations such as high electron-hole pair recombination, wide band-gap energy, aggregation at high concentration, and low surface area on photodegradation of organic dyes [22,23]. In order to increase the photocatalytic activity of TiO2 nanoparticles, graphene-like materials have attached with TiO2 nanoparticles. These carbon-based TiO2 nanoparticles have been widely used for the successful degradation of organic dyes under the irradiation of UV-light. The high photosensitivity of carbon-based TiO2 nanoparticles due to their synergetic effect between TiO2 and carbon. The green chemical assisted hydrothermal process is simple and eco-friendly methods compared to the other synthesis method of carbon-based photocatalyst as well as carbon-based TiO2 NPs nanocomposite [24]. In this context, novel titanium dioxide nanoparticles@nitrogen-doped carbon (TiO2 NPs@C) nanocomposite are established through facile green synthesis route for improvement of photosensitization.
On another hand, fluorescence-based materials have received much attention recently because of their excellent properties such as sensitivity, short response time, and low cost [25]. Thus, fluorescence materials are used in wide range of applications such as fluorescent probes in sensors and imaging [26]. Among the nanomaterials, quantum dots are one the fluorescent materials attracted the researcher much in recent years. However, quantum dots are expensive, are difficult to synthesize, and are toxic thus limits the applications in sensors and bioimaging. Therefore, researchers focused to develop new fluorescent nanomaterials with low toxicity and for a wide range of applications [27]. Carbon dots (CDs) are one kind of newly discovered fluorescent nanomaterials is popular due to their unique optical properties, biocompatible, great aqueous stability, and facile synthesis [[28], [29], [30], [31], [32], [33], [34]]. CDs and heteroatom (N, S, P, S and etc.) doped CDs have been synthesized using various methods, acidic oxidation, electrochemical synthesis, hydrothermal synthesis, laser ablation, arc discharge, and microwave-assisted synthesis [[35], [36], [37], [38], [39]]. Among the methods preparation of CDs and heteroatom doped CDs using eco-friendly biomass such as fruits and leaves via hydrothermal method is highly encouraged because of the green chemistry approach and are widely used [40].
In the present work, we approach a facile one-step synthesize of nitrogen-doped CDs and TiO2 NPs@C nanocomposite using peach fruit extract as carbon precursor via hydrothermal method. Comparing to reported methods to prepared heteroatom doped CDs and TiO2 NPs@C nanocomposite, this approach has various advantages like simple, rapid and environmentally friendly due to peach fruit is the most abundant biosource in nature. Also, the use of biosources such as peach fruit may represent an important strategy to reduce the final cost of producing the carbon nanomaterials with functional groups. The satisfactory amount of oxygen-containing and nitrogen-containing functional groups over the CDs enhance the fluorescence properties (quantum yield) with biocompatibility, allowing its potential application in bioimaging and biomedical. The photocatalytic activity of the synthesized TiO2 NPs@C nanocomposite was explored toward the photodegradation of MB as a model of pollutants in water, with the aim to evaluate the potential application of TiO2 NPs@C nanocomposite in environmental remediation. In order to find the extraordinary photocatalytic activity of synthesized TiO2 NPs@C nanocomposite, the dye degradation efficiency (%) and rate constant (k) of TiO2 NPs@C nanocomposite on MB were compared to bare TiO2 NPs.
Section snippets
Materials
The peach fruit was procured from the Kyungpook National University Campus, Daegu, Republic of Korea. Titanium (IV) isopropoxide, aqueous ammonia (25%), phosphate buffered saline (PBS), quinine sulfate, sodium azide, iodonitrotetrazolium salt (INT), sulphuric acid (H2SO4), ethanol, MB, and dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich, Republic of Korea. The yeast strains Candida albicans (C. albicans-KCTC-11282) was procured from the Korean Cell Type Culture Collection (KCTC),
Characterization of the synthesized bare TiO2 NPs, pristine carbon and TiO2 NPs@C nanocomposite
Scheme 1 shows the one-step synthesize of N-CDs as well as TiO2 NPs@C nanocomposite from peach juice using the hydrothermal method. In order to compare the properties of prepared TiO2 NPs@C nanocomposite with pristine carbon, the later one was prepared without TiO2 NPs by adopting the same method as that earlier one. The synthesized bare TiO2 NPs, TiO2 NPs@C nanocomposite, and pristine carbon were characterized by various methods. Fig. S1 shows the FESEM images and corresponding EDX pattern of
Conclusions
In this research, the hydrothermal process was employed to synthesize TiO2 NPs@C nanocomposite and N-CDs at once as a photocatalyst and label-free fluorescent probe, respectively. The new TiO2 NPs@C nanocomposite showed excellent photocatalytic performance on MB under irradiation of UV-light and the degradation efficiency (>90%) of TiO2 NPs@C nanocomposite was 5 times higher than that of bare TiO2 NPs. The intensification of photocatalytic activity of TiO2 NPs@C nanocomposite was ascribed to
Acknowledgments
This research was partially supported by the Nano Material Technology Development Program of the Korean National Research Foundation (NRF) funded by the Korean Ministry of Education, Science and Technology (2012M3A7B4049675) and the Priority Research Centers Program (2014R1A6A1031189). This work was supported by the National Research Foundation (NRF) of Korea grant funded by the Ministry of Science, Information and Communications Technology (MSIT) of Korea government (2017R1C1B5076345).
References (75)
- et al.
Sonocatalytic performance of ZnO/graphene/TiO2 nanocomposite for degradation of dye pollutants (methylene blue texbrite BAC-L, texbrite BBU-L and texbrite NFW-L) under ultrasonic irradiation
Dyes Pigments
(2016) - et al.
Photocatalytic decolourisation of methylene blue (MB) over titania pillared zirconium phosphate (ZrP) and titanium phosphate (TiP) under solar radiation
J. Mol. Catal. A
(2007) - et al.
Recent advances in floating TiO2-based photocatalysts for environmental application
Appl. Catal., B
(2018) - et al.
Enhanced photocatalytic degradation of methylene blue and methyl orange by ZnO:Eu nanoparticles
Appl. Catal., B
(2017) - et al.
Synthesis of mesoporous TiO2–curcumin nanoparticles for photocatalytic degradation of methylene blue dye
J. Photochem. Photobiol., B
(2016) - et al.
Light driven fabrication of highly dispersed Mn-Co/RGO and the synergistic effect in catalytic degradation of methylene blue
Mater. Des.
(2018) - et al.
Application of microwave irradiation in preparation and characterization of CuO/Al2O3 nanocomposite for removing MB dye from aqueous solution
J. Photochem. Photobiol., A
(2017) - et al.
Preparation of cubic Cu2O nanoparticles wrapped by reduced graphene oxide for the efficient removal of rhodamine B
J. Alloys Compd.
(2017) - et al.
Photocatalytic degradation of methylene blue under visible light irradiation by non-peripherally tetra substituted phthalocyanine-TiO2 nanocomposites
Inorg. Chim. Acta.
(2018) - et al.
Fabrication of A/R-TiO2 composite for enhanced photoelectrochemical performance: solar hydrogen generation and dye degradation
Appl. Surf. Sci.
(2017)
Detachable photocatalysts of anatase TiO2 nanoparticles: annulling surface charge for immediate photocatalyst separation
Appl. Surf. Sci.
Synthesis and photocatalytic properties of visible light responsive La/TiO2-graphene composites
Appl. Surf. Sci.
Photocatalytic degradation of methylene blue in water solution by multilayer TiO2 coating on HDPE
Appl. Surf. Sci.
An instant photo-excited electrons relaxation on the photo-degradation properties of TiO2−x films
J. Photochem. Photobiol., A
Efficient one-pot synthesis of Ag nanoparticles loaded on N-doped multiphase TiO2 hollow nanorod arrays with enhanced photocatalytic activity
Appl. Surf. Sci.
Degradation of methylene blue in aqueous dispersion of hollow titania photocatalyst: optimization of reaction by peroxydisulfate electron scavenger
J. Colloid Interface Sci.
Concurrent synthesis of nitrogen-doped carbon dots for cell imaging and ZnO@nitrogen-doped carbon sheets for photocatalytic degradation of methylene blue
J. Photochem. Photobiol., A
Study on the fluorescence characteristics of carbon dots
Spectrochim. Acta A
Fluorescent carbon dots and their sensing applications
Trends Anal. Chem.
Review on carbon dots and their applications
Chinese J. Anal. Chem.
Carbon dots: biomacromolecule interaction, bioimaging and nanomedicine
Coord. Chem. Rev.
Synthesis of highly fluorescent nitrogen-doped graphene quantum dots for sensitive, label-free detection of Fe(III) in aqueous media
Biosens. Bioelectron.
Nitrogen-doped carbon quantum dots: facile synthesis and application as a “turn-off” fluorescent probe for detection of Hg2+ ions
Biosens. Bioelectron.
Green Synthesis of carbon dots from Ocimum sanctum for effective florescent sensing of Pb2+ ions and live cell imaging
Sens. Actuators, B
Efficient synthesis of highly fluorescent nitrogen-doped carbon dots for cell imaging using unripe fruit extract of Prunus mume
Appl. Surf. Sci.
Microwave assisted green synthesis of fluorescent N-doped carbon dots: cytotoxicity and bio-imaging applications
J. Photochem. Photobiol., B
Hydrothermal conversion of Magnolia liliiflora into nitrogen-doped carbon dots as an effective turn-off fluorescence sensing, multi-colour cell imaging and fluorescent ink
Colloids Surf., B
Effective photocatalytic degradation of anthropogenic dyes using graphene oxide grafting titanium dioxide nanoparticles under UV-light irradiation
J. Photochem. Photobiol., A
Exploring potential environmental applications of TiO2 nanoparticles
Energy Procedia
Dielectric and photocatalytic properties of sulfur doped TiO2 nanoparticles prepared by ball milling
Mater. Res. Bull.
Green synthesis of nitrogen-doped graphitic carbon sheets with use of Prunus persica for supercapacitors
Appl. Surf. Sci.
Direct solvothermal synthesis of zinc oxide nanoparticle decorated graphene oxide nanocomposite for efficient photodegradation of azo-dyes
J. Photochem. Photobiol., A
Titanium dioxide encapsulated in nitrogen-doped carbon enhances the activity and durability of platinum catalyst for methanol electro-oxidation reaction
J. Power Sources
Polybenzoxazine originated N-doped mesoporous carbon ropes as an electrode material for high-performance supercapacitors
J. Alloys Compd.
Hierarchical self-supported C@TiO2-MoS2 core-shell nanofiber mats as flexible anode for advanced lithium ion batteries
Appl. Surf. Sci.
Study on highly visible light active Bi-doped TiO2 composite hollow sphere
Appl. Surf. Sci.
Facile synthesis of zinc oxide nanoparticles decorated graphene oxide composite via simple solvothermal route and their photocatalytic activity on methylene blue degradation
J. Photochem. Photobiol., B
Cited by (119)
One-step synthesis of N, S-doped carbon dots with green emission and their application in 4-NP detection, pH sensing, and cell imaging
2024, Spectrochimica Acta - Part A: Molecular and Biomolecular SpectroscopyRecent advances of CDs-based ternary heterojunctions for enhancing photocatalytic performance in the degradation of organic pollutants: A review
2024, Nano-Structures and Nano-ObjectsGreen synthesis of nano materials and their applications
2024, Comprehensive Analytical Chemistry
- ☆
Electronic Supplementary Information (ESI) available: Detailed instrumentation methods; FESEM images with EDX spectrum of bare TiO2 NPs; ATR-FTIR spectrum and excitation-dependent normalized fluorescence spectra of the obtained N-CDs.
- 1
Authors contributed equally to this work.