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Journal ArticleDOI: 10.1016/J.JALLCOM.2020.158038

Facile Synthesis of Novel Carbon Dots@Metal Organic Framework Composite for Remarkable and Highly Sustained Oxygen Evolution Reaction

05 Mar 2021-Journal of Alloys and Compounds (Elsevier)-Vol. 856, pp 158038
Abstract: Craving to search sources of energy is constantly compelling the mankind to find a source that is renewable or has enormous reservoirs and at the same time it poses no hazardous effect to mankind. Today’s energy deficient world has been seeking for an electrocatalyst which has a simple and facile synthesis strategy with marvellous catalytic performance and has outstandingly sustained stability for the highly lethargic Oxygen Evolution Reaction (OER). Here, a Ni-based mixed linker Metal Organic Framework (MOF) was synthesized using 1,3,5-benzenetricarboxylic acid (BTC) and 4,4`-bipyridine (bpy) as organic linkers. Carbon Dots (CDs) were incorporated into MOF during synthesis to impart synergistic effect to the as-synthesized composite. All the synthesized samples i.e CDs, MOF and CDs@MOF were characterized by various techniques to confirm the structural, compositional, morphological and textural analysis. The synthesized composite possessed rods like morphology with uniform distribution of CDs which offered superb stability for almost 40 hrs, large electrochemical active surface area (ECSA), least charge transfer resistance (Rct), high turnover frequency (TOF), reasonably low onset potential, low overpotential and a comparably low Tafel slope. The electrocatalyst owed its great catalytic efficiency and substantial stability due to the synergistic effect between CDs and MOF. This work is an effort to exploit the fabulous potential of MOF based nano-composite towards water splitting.

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Topics: Electrocatalyst (53%)

7 results found

Open accessJournal ArticleDOI: 10.1021/ACSANM.1C01372
Akash S. Rasal1, Sudesh Yadav2, Anchal Yadav3, Anil A. Kashale4  +3 moreInstitutions (4)
05 Jul 2021-
Abstract: Carbon quantum dots (CQDs) are a class of carbon nanomaterials that have recently gained recognition as current entrants to traditional semiconductor quantum dots. CQDs have the desirable advantages of low toxicity, environmental friendliness, low cost, photostability, favorable charge transfer with enhanced electronic conductivity, and comparable easy-synthesis protocols. This review examines the advancements in CQD research and development, with a focus on their synthesis, functionalization, and energy applications. Initially, various synthesis methods are discussed briefly with pros and cons. Herein, first top-down methods including the arc-discharge technique, laser ablation technique, plasma treatment, ultrasound synthesis technique, electrochemical technique, chemical exfoliation, and combustion were discussed briefly. The later section presents bottom-up (microwave synthesis, hydrothermal synthesis, thermal pyrolysis, and metal–organic framework template-assisted approach) and waste-derived CQD synthesis methods. The next section is focused on the energy applications of CQDs including supercapacitors, lithium-ion batteries, photovoltaics, hydrogen evolution reaction and oxygen evolution reaction. Finally, challenges and future perspectives in this exciting and promising area are presented.

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7 Citations

Open accessJournal ArticleDOI: 10.1016/J.MTNANO.2021.100124
Enlai Hu1, Yue Yao1, Yuanjing Cui1, Guodong Qian1Institutions (1)
Abstract: Water splitting is considered as a promising approach to generate hydrogen. At present, considerable efforts have been devoted to design and develop robust catalysts for efficient hydrogen generation through water splitting. To further decrease the energy consumption and lower the cost of the catalysts, it demands earth-abundant metal-based catalysts as alternatives to catalyze the water splitting. Metal–organic frameworks (MOFs) composed of metal nodes and organic linkers have been illustrated to be efficient for water splitting, because of their large specific surface area and tunable composition. Recent progress in the pure MOFs and their composites toward water splitting is summarized and strategies to boost the catalytic performance of MOFs are also introduced. Finally, the current challenges and future aims of pure MOFs-based catalysts toward water splitting are proposed.

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Topics: Water splitting (60%)

1 Citations

Journal ArticleDOI: 10.1016/J.JALLCOM.2021.160667
Zhang Zhiliang1, Xu Deyao1, Junhua Li2, Jinlong Liu1  +7 moreInstitutions (4)
Abstract: We rationally design and construct a heterostructured hybrid with reduced graphene oxide served as a platform to in-situ grow N-doped bamboo-like carbon nanotubes encapsulating bimetallic Co–Fe sulfide nanoparticles through a two-stage pyrolysis succeeded by an evaporating sulfurization process (denoted as CoxFe1-xS2@N-CNTs/rGO). By tuning the Co/Fe ratio, the optimal Co0.6Fe0.4S2@N-CNTs/rGO exhibits a remarkable oxygen evolution reaction (OER) performance in 1.0 M KOH, in which the overpotential at 10 mA cm−2 and Tafel slope are recorded as 248 mV (vs. RHE) and 58.3 mV dec−1, respectively, outmaneuvring commercial RuO2 and most Co/Fe sulfide-based catalysts in recent peer reports. Comprehensive experiment results unravel that the outstanding OER electrocatalytic performance owes to the reinforced synergy between CoS2 and FeS2, the heterostructures constituted by partial CoS2 and FeS2, the confining effect of N-CNTs/rGO for CoS2 and FeS2 nanoparticles, and the high conductivity and large surface of N-CNTs/rGO.

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Topics: Graphene (53%), Sulfide (53%), Carbon nanotube (53%) ... show more

1 Citations

Journal ArticleDOI: 10.1016/J.IJHYDENE.2021.08.158
Guyang Ning1, Mingxuan Fu1, Jiaxian Liu1, Yuena Sun1  +5 moreInstitutions (1)
Abstract: Transition metal catalysts were supposed to be the most likely substitute for commercial noble metal catalysts, and the development of highly active and long-term catalyst for water splitting are the future trend. Herein, Ni rectangular nitrogen doped carbon nanorods@Fe–Co nanocubes (Ni-CNRs@Fe–Co cubes) were fabricated via a facile template-free method. This simple strategy not only realizes the structure tailoring, but also achieves high-quality nitrogen-doping. Specifically, nickel dimethylglyoxime [Ni(dmg)2] with rectangular rodlike structure was firstly synthesized by solution method, then metal-organic frameworks Fe–Co nanocube with different contents were loaded on rectangular carbon nanorods with polydopamine as the locating and the connecting agent, and finally Ni-CNRs@xFe-Co cubes were obtained by a one-step calcination. A series of electrochemical tests were researched on materials with different metal contents in the 1 M KOH solution. The Ni-CNRs@Fe–Co cubes show excellent electrocatalytic activity in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). For HER and OER, the Tafel slopes were 83.3 mV dec−1 and 71 mV dec−1, the onset potential were −167 mV and 1.62 V, and reached the current densities of 10 mA cm−2, the overpotential just needed 196 mV and 433 mV, respectively. This novel synthetic strategy will provide a template-free way for cheap electrocatalysts of non-precious metal for OER and HER.

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Topics: Water splitting (53%), Overpotential (52%), Noble metal (52%) ... show more


72 results found

Open accessJournal ArticleDOI: 10.1038/NATURE01650
Omar M. Yaghi1, Michael O'Keeffe2, Nathan W. Ockwig1, Hee K. Chae3  +3 moreInstitutions (3)
12 Jun 2003-Nature
Abstract: The long-standing challenge of designing and constructing new crystalline solid-state materials from molecular building blocks is just beginning to be addressed with success. A conceptual approach that requires the use of secondary building units to direct the assembly of ordered frameworks epitomizes this process: we call this approach reticular synthesis. This chemistry has yielded materials designed to have predetermined structures, compositions and properties. In particular, highly porous frameworks held together by strong metal-oxygen-carbon bonds and with exceptionally large surface area and capacity for gas storage have been prepared and their pore metrics systematically varied and functionalized.

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7,384 Citations

Journal ArticleDOI: 10.1039/B802426J
Abstract: Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal–organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).

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Topics: Gas separation (59%), Selective adsorption (55%), Adsorption (55%) ... show more

6,297 Citations

Open accessJournal ArticleDOI: 10.1038/NATURE05545
01 Mar 2007-Nature
Abstract: Graphene — a recently isolated one-atom-thick layered form of graphite — is a hot topic in the materials science and condensed matter physics communities, where it is proving to be a popular model system for investigation. An experiment involving individual graphene sheets suspended over a microscale scaffold has allowed structure determination using transmission electron microscopy and diffraction, perhaps paving the way towards an answer to the question of why graphene can exist at all. The 'two-dimensional' sheets, it seems, are not flat, but wavy. The undulations are less pronounced in a two-layer system, and disappear in multilayer samples. Learning more about this 'waviness' may reveal what makes these extremely thin carbon membranes so stable. Investigations of individual graphene sheets freely suspended on a microfabricated scaffold in vacuum or in air reveal that the membranes are not perfectly flat, but exhibit an intrinsic waviness, such that the surface normal varies by several degrees, and out-of-plane deformations reach 1 nm. The recent discovery of graphene has sparked much interest, thus far focused on the peculiar electronic structure of this material, in which charge carriers mimic massless relativistic particles1,2,3. However, the physical structure of graphene—a single layer of carbon atoms densely packed in a honeycomb crystal lattice—is also puzzling. On the one hand, graphene appears to be a strictly two-dimensional material, exhibiting such a high crystal quality that electrons can travel submicrometre distances without scattering. On the other hand, perfect two-dimensional crystals cannot exist in the free state, according to both theory and experiment4,5,6,7,8,9. This incompatibility can be avoided by arguing that all the graphene structures studied so far were an integral part of larger three-dimensional structures, either supported by a bulk substrate or embedded in a three-dimensional matrix1,2,3,9,10,11,12. Here we report on individual graphene sheets freely suspended on a microfabricated scaffold in vacuum or air. These membranes are only one atom thick, yet they still display long-range crystalline order. However, our studies by transmission electron microscopy also reveal that these suspended graphene sheets are not perfectly flat: they exhibit intrinsic microscopic roughening such that the surface normal varies by several degrees and out-of-plane deformations reach 1 nm. The atomically thin single-crystal membranes offer ample scope for fundamental research and new technologies, whereas the observed corrugations in the third dimension may provide subtle reasons for the stability of two-dimensional crystals13,14,15.

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Topics: Bilayer graphene (60%), Graphene (56.99%)

4,295 Citations

Journal ArticleDOI: 10.1126/SCIENCE.1083440
16 May 2003-Science
Abstract: Metal-organic framework-5 (MOF-5) of composition Zn4O(BDC)3 (BDC = 1,4-benzenedicarboxylate) with a cubic three-dimensional extended porous structure adsorbed hydrogen up to 4.5 weight percent (17.2 hydrogen molecules per formula unit) at 78 kelvin and 1.0 weight percent at room temperature and pressure of 20 bar. Inelastic neutron scattering spectroscopy of the rotational transitions of the adsorbed hydrogen molecules indicates the presence of two well-defined binding sites (termed I and II), which we associate with hydrogen binding to zinc and the BDC linker, respectively. Preliminary studies on topologically similar isoreticular metal-organic framework-6 and -8 (IRMOF-6 and -8) having cyclobutylbenzene and naphthalene linkers, respectively, gave approximately double and quadruple (2.0 weight percent) the uptake found for MOF-5 at room temperature and 10 bar.

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Topics: Hydrogen storage (55%), Hydrogen (54%), Metal-organic framework (51%) ... show more

3,984 Citations

Journal ArticleDOI: 10.1038/35104599
M. S. Dresselhaus1, I. L. Thomas2Institutions (2)
15 Nov 2001-Nature
Abstract: Fossil fuels currently supply most of the world's energy needs, and however unacceptable their long-term consequences, the supplies are likely to remain adequate for the next few generations. Scientists and policy makers must make use of this period of grace to assess alternative sources of energy and determine what is scientifically possible, environmentally acceptable and technologically promising.

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3,330 Citations