scholarly journals Mesoporous Tungsten Trioxide Photoanodes Modified with Nitrogen-Doped Carbon Quantum Dots for Enhanced Oxygen Evolution Photo-Reaction

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1502 ◽  
Author(s):  
Mabrook S. Amer ◽  
Prabhakarn Arunachalam ◽  
Abdullah M. Al-Mayouf ◽  
Saradh Prasad ◽  
Matar N. Alshalwi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Charge Carrier ◽  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Tungsten Trioxide ◽  
High Surface ◽  
Carbon Quantum Dots ◽  
Transmission Microscopy ◽  
X Ray ◽  
Carrier Separation

Nanostructured photoanodes are attractive materials for hydrogen production via water photo-electrolysis process. This study focused on the incorporation of carbon quantum dots doped with nitrogen as a photosensitizer into mesoporous tungsten trioxide photoanodes (N-CQD/meso-WO3) using a surfactant self-assembly template approach. The crystal structure, composition, and morphology of pure and N-CQD- modified mesoporous WO3 photoanodes were investigated using scanning electron and transmission microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Due to their high surface area, enhanced optical absorption, and charge-carrier separation and transfer, the resulting N-CQD/meso-WO3 photoanodes exhibited a significantly enhanced photocurrent density of 1.45 mA cm−2 at 1.23 V vs. RHE under AM 1.5 G illumination in 0.5 M Na2SO4 without any co-catalysts or sacrificial reagent, which was about 2.23 times greater than its corresponding pure meso-WO3. Moreover, the oxygen evolution onset potential of the N-CQD/meso-WO3 photoanodes exhibited a negative shift of 95 mV, signifying that both the charge-carrier separation and transfer processes were promoted.

scholarly journals The Application of Green-Synthesis-Derived Carbon Quantum Dots to Bioimaging and the Analysis of Mercury(II)

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Qianchun Zhang ◽  
Xiaolan Zhang ◽  
Linchun Bao ◽  
Yun Wu ◽  
Li Jiang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Hela Cells ◽  
Photoelectron Spectroscopy ◽  
Water Solubility ◽  
Limit Of Detection ◽  
Carbon Quantum Dots ◽  
Coefficient Of Determination ◽  
Serum Samples ◽  
X Ray ◽  
Transmission Electron

Ginkgo leaves were used as precursors for the hydrothermal synthesis of carbon quantum dots (CQDs), which were subsequently characterized by transmission electron microscopy as well as Fourier-transform infrared, X-ray powder diffraction, and X-ray photoelectron spectroscopy. The prepared CQDs exhibited a fluorescence quantum yield of 11% and superior water solubility and fluorescence stability, as well as low cytotoxicities and excellent biocompatibilities with A549 and HeLa cells; these CQDs were also used to bioimage HeLa cells. Moreover, owing to the experimental observation that Hg2+ quenches the fluorescence of the CQDs in a specific and sensitive manner, we developed a method for the detection of Hg2+ using this fluorescence sensor. The sensor exhibited a linear range for Hg2+ of 0.50–20 μM, with an excellent coefficient of determination (R2 = 0.9966) and limit of detection (12.4 nM). In practice, the proposed method was shown to be highly selective and sensitive for the monitoring of Hg2+ in lake water and serum samples.

scholarly journals Nanotubular Titanium Oxynitride with an Ultra-Low Iridium Loading as a High-Performance Oxygen-Evolution-Reaction Thin-Film Electrode

2020 ◽  
Author(s):  
Marjan Bele ◽  
Primož Jovanovič ◽  
Živa Marinko ◽  
Sandra Drev ◽  
Vid Simon Šelih ◽  
...  
Keyword(s):  
Thin Film ◽  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
High Performance ◽  
High Surface ◽  
High Surface Area ◽  
Additional Contribution ◽  
X Ray ◽  
Metal Support Interaction

The present study targets one of the grand challenges of electrochemical hydrogen production: a durable and cost-effective oxygen-evolution catalyst. We present a thin-film composite electrode with a unique morphology and an ultra-low loading of iridium that has extraordinary electrocatalytic properties. This is accomplished by the electrochemical growth of a defined, high-surface-area titanium oxide nanotubular film followed by the nitridation and effective immobilization of iridium nanoparticles. The applicative relevance of this production process is justified by a remarkable oxygen-evolution reaction (OER) activity and high stability. Due to the confinement inside the pores and the strong metal-support interaction (SMSI) effects, the OER exhibited a higher turnover. The high durability is achieved by self-passivation of the titanium oxynitride (TiON) surface layer with TiO<sub>2</sub>, which in addition also effectively embeds the Ir nanoparticles, while still keeping them electrically wired. An additional contribution to the enhanced durability comes from the nitrogen atoms, which according to our DFT calculations reduce the tendency of the Ir nanoparticles to grow. We also introduce an advanced electrochemical characterization platform for the in-depth study of thin-film electrodes. Namely, the entire process of the TiON-Ir electrode’s preparation and the electrochemical evaluation can be tracked with scanning electron microscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) at identical locations. In general, the novel experimental approach allows for the unique morphological, structural and compositional insights into the preparation and electrocatalytic performance of thin films, making it useful also outside electrocatalysis applications.

Nanotubular Titanium Oxynitride with an Ultra-Low Iridium Loading as a High-Performance Oxygen-Evolution-Reaction Thin-Film Electrode

2020 ◽  
Author(s):  
Marjan Bele ◽  
Primož Jovanovič ◽  
Živa Marinko ◽  
Sandra Drev ◽  
Vid Simon Šelih ◽  
...  
Keyword(s):  
Thin Film ◽  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
High Performance ◽  
High Surface ◽  
High Surface Area ◽  
Additional Contribution ◽  
X Ray ◽  
Metal Support Interaction

The present study targets one of the grand challenges of electrochemical hydrogen production: a durable and cost-effective oxygen-evolution catalyst. We present a thin-film composite electrode with a unique morphology and an ultra-low loading of iridium that has extraordinary electrocatalytic properties. This is accomplished by the electrochemical growth of a defined, high-surface-area titanium oxide nanotubular film followed by the nitridation and effective immobilization of iridium nanoparticles. The applicative relevance of this production process is justified by a remarkable oxygen-evolution reaction (OER) activity and high stability. Due to the confinement inside the pores and the strong metal-support interaction (SMSI) effects, the OER exhibited a higher turnover. The high durability is achieved by self-passivation of the titanium oxynitride (TiON) surface layer with TiO<sub>2</sub>, which in addition also effectively embeds the Ir nanoparticles, while still keeping them electrically wired. An additional contribution to the enhanced durability comes from the nitrogen atoms, which according to our DFT calculations reduce the tendency of the Ir nanoparticles to grow. We also introduce an advanced electrochemical characterization platform for the in-depth study of thin-film electrodes. Namely, the entire process of the TiON-Ir electrode’s preparation and the electrochemical evaluation can be tracked with scanning electron microscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) at identical locations. In general, the novel experimental approach allows for the unique morphological, structural and compositional insights into the preparation and electrocatalytic performance of thin films, making it useful also outside electrocatalysis applications.

scholarly journals Carbon Quantum Dots Modified (002) Oriented Bi2O2CO3 Composites with Enhanced Photocatalytic Removal of Toluene in Air

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1795
Author(s):  
Junping Ding ◽  
Huanchun Wang ◽  
Yidong Luo ◽  
Yushuai Xu ◽  
Jinsheng Liu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Carbon Quantum Dots ◽  
Spherical Particles ◽  
Chemical Route ◽  
X Ray ◽  
Photocatalytic Removal ◽  
Efficient Charge ◽  
Gaseous Toluene

In work, (002) oriented flower-like Bi2O2CO3(BOC) composites are synthesized by a facile chemical route and carbon quantum dots (CQDs) are modified on their surfaces through a hydrothermal method. The synthesized samples (CQD/BOC) are characterized by X-ray diffraction (XRD), SEM, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuser reflectances (DRS), BET and TEM/HRTEM. The morphologies of CQD/BOC composites are the flower-like shapes, the irregular flaky structures and the fine spherical particles of CQDs attached. Photocatalytic performances were investigated in terms of removing gaseous toluene at a concentration of 94.3ppm in air, with the assistance of CQD/BOC under artificial irradiation. Our results show that CQDs modified (002) oriented Bi2O2CO3 exhibits good photocatalytic activity for toluene decomposition, which can be attributed to the enhanced efficient charge separation. A certain ratio composite photocatalyst (BOC-CQD-15) shows a toluene removal rate of 96.62% in three hours, as well as great stability. CO2 was verified to be the primary product. The oriented flower-like Bi2O2CO3 with carbon quantum dots on the surface shows great potential in the field of solar driven air purification.

scholarly journals Non-Thermal Plasma-Modified Ru-Sn-Ti Catalyst for Chlorinated Volatile Organic Compound Degradation

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1456
Author(s):  
Yujie Fu ◽  
You Zhang ◽  
Qi Xin ◽  
Zhong Zheng ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Surface Oxidation ◽  
Treatment Method ◽  
X Ray ◽  
Chlorinated Volatile Organic Compounds ◽  
Volatile Organic ◽  
Doped Titania

Chlorinated volatile organic compounds (CVOCs) are vital environmental concerns due to their low biodegradability and long-term persistence. Catalytic combustion technology is one of the more commonly used technologies for the treatment of CVOCs. Catalysts with high low-temperature activity, superior selectivity of non-toxic products, and resistance to chlorine poisoning are desirable. Here we adopted a plasma treatment method to synthesize a tin-doped titania loaded with ruthenium dioxide (RuO2) catalyst, possessing enhanced activity (T90%, the temperature at which 90% of dichloromethane (DCM) is decomposed, is 262 °C) compared to the catalyst prepared by the conventional calcination method. As revealed by transmission electron microscopy, X-ray diffraction, N2 adsorption, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction, the high surface area of the tin-doped titania catalyst and the enhanced dispersion and surface oxidation of RuO2 induced by plasma treatment were found to be the main factors determining excellent catalytic activities.

Polarization-induced charge carrier separation in polar and nonpolar grown GaN quantum dots

2009 ◽  
Vol 106 (8) ◽  
pp. 083707 ◽  
Author(s):  
Oliver Marquardt ◽  
Tilmann Hickel ◽  
Jörg Neugebauer
Keyword(s):  
Quantum Dots ◽  
Charge Carrier ◽  
Induced Charge ◽  
Carrier Separation

Coupling NiCo catalysts with carbon quantum dots on hematite photoanodes for highly efficient oxygen evolution

2022 ◽  
Author(s):  
Yingpu Bi ◽  
Bin zhao ◽  
Chenchen Feng ◽  
Xiaojuan Huang ◽  
Yong Ding
Keyword(s):  
Quantum Dots ◽  
Water Splitting ◽  
Oxygen Evolution ◽  
Carbon Quantum Dots ◽  
Hole Transfer ◽  
Highly Efficient ◽  
Pec Water Splitting

Highly efficient hole transfer from photoanodes to oxygen evolution catalysts is crucial for solar photoelectrochemical (PEC) water splitting. Herein, we demonstrated the coupling of NiCo catalysts with carbon quantum dots...

Insights into the Electronic Structure of Fe Penta-Coordinated Complexes. Spectroscopic Examination and Electrochemical Analysis for the Oxygen Reduction and Oxygen Evolution Reactions.

2021 ◽  
Author(s):  
César Zúñiga-Loyola ◽  
Gabriel Abarca ◽  
Maria Soledad Ureta-Zanartu ◽  
Carolina Aliaga ◽  
Jose Zagal ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electronic Structure ◽  
Oxygen Reduction ◽  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Analysis ◽  
X Ray ◽  
Spectroscopic Examination ◽  
Modified Carbon Nanotubes

Fe phthalocyanine was coordinated to pyridine-modified carbon nanotubes and studied as a catalyst for the oxygen reduction (ORR) and oxygen evolution reactions (OER). X-ray Photoelectron Spectroscopy (XPS), Mössbauer, and Electron...

scholarly journals Nitrogen-Doped Sponge Ni Fibers as Highly Efficient Electrocatalysts for Oxygen Evolution Reaction

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Kaili Zhang ◽  
Xinhui Xia ◽  
Shengjue Deng ◽  
Yu Zhong ◽  
Dong Xie ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
High Performance ◽  
Active Phase ◽  
X Ray ◽  
Highly Active ◽  
N Doping ◽  
Energy Conversion Devices

Abstract Controllable synthesis of highly active micro/nanostructured metal electrocatalysts for oxygen evolution reaction (OER) is a particularly significant and challenging target. Herein, we report a 3D porous sponge-like Ni material, prepared by a facile hydrothermal method and consisting of cross-linked micro/nanofibers, as an integrated binder-free OER electrocatalyst. To further enhance the electrocatalytic performance, an N-doping strategy is applied to obtain N-doped sponge Ni (N-SN) for the first time, via NH3 annealing. Due to the combination of the unique conductive sponge structure and N doping, the as-obtained N-SN material shows improved conductivity and a higher number of active sites, resulting in enhanced OER performance and excellent stability. Remarkably, N-SN exhibits a low overpotential of 365 mV at 100 mA cm−2 and an extremely small Tafel slope of 33 mV dec−1, as well as superior long-term stability, outperforming unmodified sponge Ni. Importantly, the combination of X-ray photoelectron spectroscopy and near-edge X-ray adsorption fine structure analyses shows that γ-NiOOH is the surface-active phase for OER. Therefore, the combination of conductive sponge structure and N-doping modification opens a new avenue for fabricating new types of high-performance electrodes with application in electrochemical energy conversion devices.

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