The Experts below are selected from a list of 108555 Experts worldwide ranked by ideXlab platform
Stephen R Leone - One of the best experts on this subject based on the ideXlab platform.
-
operando spectroscopic analysis of an amorphous cobalt sulfide hydrogen evolution electrocatalyst
Journal of the American Chemical Society, 2015Co-Authors: Nikolay Kornienko, Joaquin Resasco, Nigel Becknell, Changming Jiang, Yisheng Liu, Kaiqi Nie, Xuhui Sun, Jinghua Guo, Stephen R LeoneAbstract:The generation of Chemical Fuel in the form of molecular H2 via the electrolysis of water is regarded to be a promising approach to convert incident solar power into an energy storage medium. Highly efficient and cost-effective catalysts are required to make such an approach practical on a large scale. Recently, a number of amorphous hydrogen evolution reaction (HER) catalysts have emerged that show promise in terms of scalability and reactivity, yet remain poorly understood. In this work, we utilize Raman spectroscopy and X-ray absorption spectroscopy (XAS) as a tool to elucidate the structure and function of an amorphous cobalt sulfide (CoSx) catalyst. Ex situ measurements reveal that the as-deposited CoSx catalyst is composed of small clusters in which the cobalt is surrounded by both sulfur and oxygen. Operando experiments, performed while the CoSx is catalyzing the HER, yield a molecular model in which cobalt is in an octahedral CoS2-like state where the cobalt center is predominantly surrounded by a first shell of sulfur atoms, which, in turn, are preferentially exposed to electrolyte relative to bulk CoS2. We surmise that these CoS2-like clusters form under cathodic polarization and expose a high density of catalytically active sulfur sites for the HER.
Joseph Wang - One of the best experts on this subject based on the ideXlab platform.
-
metal organic frameworks as micromotors with tunable engines and brakes
Journal of the American Chemical Society, 2017Co-Authors: Wenjuan Liu, Joseph Wang, Elodie Sandraz, Hsin Lan, Seth M CohenAbstract:Herein, we report that UiO-type (UiO = University of Oslo) metal–organic frameworks (MOFs) can be transformed into self-propelled micromotors by employing several different metal-based propulsion systems. Incorporation of a bipyridine ligand into the UiO-67 lattice transforms the crystallites, upon metalation, into single-site, metal-based catalytic “engines” to power the micromotors with Chemical Fuel. The “engine performance” (i.e., propulsion) of the single-site powered micromotors has been tuned by the choice of the metal ion utilized. In addition, a Chemical “braking” system was achieved by adding chelating agents capable of sequestering the metal ion engines and thereby suppressing the catalytic activity, with different chelators displaying different deceleration capacities. These results demonstrate that MOFs can be powered by various engines and halted by different brakes, resulting in a high degree of motion design and control at the nanoscale.
-
magneto acoustic hybrid nanomotor
Nano Letters, 2015Co-Authors: Jinxing Li, Tailin Xu, Tianlong Li, Melek Kiristi, Zhiguang Wu, Joseph WangAbstract:Efficient and controlled nanoscale propulsion in harsh environments requires careful design and manufacturing of nanomachines, which can harvest and translate the propelling forces with high spatial and time resolution. Here we report a new class of artificial nanomachine, named magneto–acoustic hybrid nanomotor, which displays efficient propulsion in the presence of either magnetic or acoustic fields without adding any Chemical Fuel. These Fuel-free hybrid nanomotors, which comprise a magnetic helical structure and a concave nanorod end, are synthesized using a template-assisted electroChemical deposition process followed by segment-selective Chemical etching. Dynamic switching of the propulsion mode with reversal of the movement direction and digital speed regulation are demonstrated on a single nanovehicle. These hybrid nanomotors exhibit a diverse biomimetic collective behavior, including stable aggregation, swarm motion, and swarm vortex, triggered in response to different field inputs. Such adaptive...
-
Vapor-Driven Propulsion of Catalytic Micromotors
Scientific Reports, 2015Co-Authors: Renfeng Dong, Biye Ren, David Saintillan, Barath Ezhilan, Isaac Rozen, Tailin Xu, Jinxing Li, Caleb Christianson, Wei Gao, Joseph WangAbstract:Chemically-powered micromotors offer exciting opportunities in diverse fields, including therapeutic delivery, environmental remediation, and nanoscale manufacturing. However, these nanovehicles require direct addition of high concentration of Chemical Fuel to the motor solution for their propulsion. We report the efficient vapor-powered propulsion of catalytic micromotors without direct addition of Fuel to the micromotor solution. Diffusion of hydrazine vapor from the surrounding atmosphere into the sample solution is instead used to trigger rapid movement of iridium-gold Janus microsphere motors. Such operation creates a new type of remotely-triggered and powered catalytic micro/nanomotors that are responsive to their surrounding environment. This new propulsion mechanism is accompanied by unique phenomena, such as the distinct off-on response to the presence of Fuel in the surrounding atmosphere, and spatio-temporal dependence of the motor speed borne out of the concentration gradient evolution within the motor solution. The relationship between the motor speed and the variables affecting the Fuel concentration distribution is examined using a theoretical model for hydrazine transport, which is in turn used to explain the observed phenomena. The vapor-powered catalytic micro/nanomotors offer new opportunities in gas sensing, threat detection, and environmental monitoring, and open the door for a new class of environmentally-triggered micromotors.
-
Catalytic iridium-based Janus micromotors powered by ultralow levels of Chemical Fuels
Journal of the American Chemical Society, 2014Co-Authors: Allen Pei, Renfeng Dong, Joseph WangAbstract:We describe catalytic micromotors powered by remarkably low concentrations of Chemical Fuel, down to the 0.0000001% level. These Janus micromotors rely on an iridium hemispheric layer for the catalytic decomposition of hydrazine in connection to SiO2 spherical particles. The micromotors are self-propelled at a very high speed (of ~20 body lengths s(-1)) in a 0.001% hydrazine solution due to osmotic effects. Such a low Fuel concentration represents a 10,000-fold decrease in the level required for common catalytic nanomotors. The attractive propulsion performance, efficient catalytic energy-harvesting, environmentally triggered swarming behavior, and magnetic control of the new Janus micromotors hold considerable promise for diverse practical applications.
M Jamesh - One of the best experts on this subject based on the ideXlab platform.
-
recent progress on earth abundant electrocatalysts for oxygen evolution reaction oer in alkaline medium to achieve efficient water splitting a review
Journal of Power Sources, 2018Co-Authors: M JameshAbstract:Abstract Developing earth-abundant-electrocatalysts for oxygen evolution reaction is one of the promising ways to achieve efficient water-splitting for hydrogen production (a clean Chemical Fuel). This paper reviews the activity, stability and durability for oxygen evolution reaction in alkaline medium of different types of recently reported electrocatalysts such as Ni, Co, NiCo, Fe, Se, Mo, Cu, Mn, Zn, V, Ti/Ta, and metal free based earth-abundant-electrocatalysts. Further, this paper reviews the strategies used to achieve the remarkably low overpotential (including η10: ≤100 mV), high long term stability (including ≥100 h) and high durability (including ≥5000 cycles) of earth-abundant-electrocatalysts for oxygen evolution reaction in alkaline medium and those are better or well comparable with the state-of-the-art IrO2 electrocatalyst2. Finally, this paper summarizes the efficient strategies such as preparing porous or nanostructured materials, preparing quantum sized materials, doping metals or heteroatoms, tuning the optimal crystal structure, preparing bimetallic/multi-metallic materials, preparing materials with oxygen vacancies/defects, preparing amorphous materials, preparing metal chalcogenides, preparing metal oxy hydroxides, and integrating electrocatalysts with carbon to enhance the activity, stability, and durability for OER.
-
recent progress on earth abundant hydrogen evolution reaction and oxygen evolution reaction bifunctional electrocatalyst for overall water splitting in alkaline media
Journal of Power Sources, 2016Co-Authors: M JameshAbstract:Abstract ElectroChemical water-splitting is one of the promising ways for producing clean Chemical Fuel (Hydrogen) while cheap-earth-abundant-bifunctional-electrocatalyst is one of the possible way for improving the overall cost efficiency of water-splitting. This paper reviews the Chemical state, hydrogen and oxygen evolution reaction activity in alkaline media, overall water-splitting performance in alkaline media, stability, and possible-factors for improving its efficiency of various kinds of recently reported electrocatalyst such as Ni-P, Co-P, Ni-Co-P, graphene-Co-P, O/N/C-Co/Ni, Ni-S, B-Ni/Co, Ni-Co, Mo, Se, Fe, Mn/Zn/Ti, and metal-free based earth-abundant-bifunctional-electrocatalyst. This paper also reviews and highlights the remarkable water splitting performance of the earth-abundant-bifunctional-electrocatalyst those exhibit better or well comparable with Pt/C//RuO 2 .
Nikolay Kornienko - One of the best experts on this subject based on the ideXlab platform.
-
operando spectroscopic analysis of an amorphous cobalt sulfide hydrogen evolution electrocatalyst
Journal of the American Chemical Society, 2015Co-Authors: Nikolay Kornienko, Joaquin Resasco, Nigel Becknell, Changming Jiang, Yisheng Liu, Kaiqi Nie, Xuhui Sun, Jinghua Guo, S Leone, Peidong YangAbstract:The generation of Chemical Fuel in the form of molecular H2 via the electrolysis of water is regarded to be a promising approach to convert incident solar power into an energy storage medium. Highly efficient and cost-effective catalysts are required to make such an approach practical on a large scale. Recently, a number of amorphous hydrogen evolution reaction (HER) catalysts have emerged that show promise in terms of scalability and reactivity, yet remain poorly understood. In this work, we utilize Raman spectroscopy and X-ray absorption spectroscopy (XAS) as a tool to elucidate the structure and function of an amorphous cobalt sulfide (CoSx) catalyst. Ex situ measurements reveal that the as-deposited CoSx catalyst is composed of small clusters in which the cobalt is surrounded by both sulfur and oxygen. Operando experiments, performed while the CoSx is catalyzing the HER, yield a molecular model in which cobalt is in an octahedral CoS2-like state where the cobalt center is predominantly surrounded by a...
-
operando spectroscopic analysis of an amorphous cobalt sulfide hydrogen evolution electrocatalyst
Journal of the American Chemical Society, 2015Co-Authors: Nikolay Kornienko, Joaquin Resasco, Nigel Becknell, Changming Jiang, Yisheng Liu, Kaiqi Nie, Xuhui Sun, Jinghua Guo, Stephen R LeoneAbstract:The generation of Chemical Fuel in the form of molecular H2 via the electrolysis of water is regarded to be a promising approach to convert incident solar power into an energy storage medium. Highly efficient and cost-effective catalysts are required to make such an approach practical on a large scale. Recently, a number of amorphous hydrogen evolution reaction (HER) catalysts have emerged that show promise in terms of scalability and reactivity, yet remain poorly understood. In this work, we utilize Raman spectroscopy and X-ray absorption spectroscopy (XAS) as a tool to elucidate the structure and function of an amorphous cobalt sulfide (CoSx) catalyst. Ex situ measurements reveal that the as-deposited CoSx catalyst is composed of small clusters in which the cobalt is surrounded by both sulfur and oxygen. Operando experiments, performed while the CoSx is catalyzing the HER, yield a molecular model in which cobalt is in an octahedral CoS2-like state where the cobalt center is predominantly surrounded by a first shell of sulfur atoms, which, in turn, are preferentially exposed to electrolyte relative to bulk CoS2. We surmise that these CoS2-like clusters form under cathodic polarization and expose a high density of catalytically active sulfur sites for the HER.
Peidong Yang - One of the best experts on this subject based on the ideXlab platform.
-
operando spectroscopic analysis of an amorphous cobalt sulfide hydrogen evolution electrocatalyst
Journal of the American Chemical Society, 2015Co-Authors: Nikolay Kornienko, Joaquin Resasco, Nigel Becknell, Changming Jiang, Yisheng Liu, Kaiqi Nie, Xuhui Sun, Jinghua Guo, S Leone, Peidong YangAbstract:The generation of Chemical Fuel in the form of molecular H2 via the electrolysis of water is regarded to be a promising approach to convert incident solar power into an energy storage medium. Highly efficient and cost-effective catalysts are required to make such an approach practical on a large scale. Recently, a number of amorphous hydrogen evolution reaction (HER) catalysts have emerged that show promise in terms of scalability and reactivity, yet remain poorly understood. In this work, we utilize Raman spectroscopy and X-ray absorption spectroscopy (XAS) as a tool to elucidate the structure and function of an amorphous cobalt sulfide (CoSx) catalyst. Ex situ measurements reveal that the as-deposited CoSx catalyst is composed of small clusters in which the cobalt is surrounded by both sulfur and oxygen. Operando experiments, performed while the CoSx is catalyzing the HER, yield a molecular model in which cobalt is in an octahedral CoS2-like state where the cobalt center is predominantly surrounded by a...