The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Raymond E. Schaak - One of the best experts on this subject based on the ideXlab platform.
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general strategy for the synthesis of transition metal phosphide films for electrocatalytic hydrogen and oxygen evolution
ACS Applied Materials & Interfaces, 2016Co-Authors: Carlos G Read, Juan F Callejas, Cameron F Holder, Raymond E. SchaakAbstract:Transition metal Phosphides recently have been identified as promising Earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Here, we present a general and scalable strategy for the synthesis of transition metal phosphide electrodes based on the reaction of commercially available metal foils (Fe, Co, Ni, Cu, and NiFe) with various organophosphine reagents. The resulting phosphide electrodes were found to exhibit excellent electrocatalytic HER and OER performance. The most active electrodes required overpotentials of only −128 mV for the HER in acid (Ni2P), −183 mV for the HER in base (Ni2P), and 277 mV for the OER in base (NiFeP) to produce operationally relevant current densities of 10 mA cm–2. Such HER and OER performance compares favorably with samples prepared using significantly more elaborate and costly procedures. Furthermore, we demonstrate that the approach can also be utilized to obtain highly active and conformal metal phosphide coati...
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nanostructured co2p electrocatalyst for the hydrogen evolution reaction and direct comparison with morphologically equivalent cop
Chemistry of Materials, 2015Co-Authors: Juan F Callejas, Carlos G Read, Eric J Popczun, Joshua M Mcenaney, Raymond E. SchaakAbstract:Metal Phosphides have emerged as promising Earth-abundant alternatives to platinum for catalyzing the hydrogen evolution reaction (HER) in acidic aqueous solutions. Here, Co2P nanoparticles having a hollow, multifaceted, crystalline morphology have been evaluated as HER electrocatalysts at a mass loading of 1 mg cm–2 on Ti foil substrates. The Co2P/Ti electrodes required low overpotentials of −95 and −109 mV to produce operationally relevant cathodic current densities of −10 and −20 mA cm–2, respectively. These values establish Co2P nanoparticles as highly active Earth-abundant HER catalyst materials. Importantly, the Co2P nanoparticles are morphologically equivalent to previously reported CoP nanoparticle HER catalysts, allowing a direct side-by-side evaluation of their HER activities. Such comparisons of different metal phosphide HER catalysts with the same constituent elements and morphologies are important for identifying the key materials characteristics that lead to high activity.
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electrocatalytic and photocatalytic hydrogen production from acidic and neutral ph aqueous solutions using iron phosphide nanoparticles
ACS Nano, 2014Co-Authors: Juan F Callejas, Carlos G Read, Eric J Popczun, Joshua M Mcenaney, Chance J Crompton, Adam J Biacchi, Thomas R Gordon, Nathan S Lewis, Raymond E. SchaakAbstract:Nanostructured transition-metal Phosphides have recently emerged as Earth-abundant alternatives to platinum for catalyzing the hydrogen-evolution reaction (HER), which is central to several clean energy technologies because it produces molecular hydrogen through the electrochemical reduction of water. Iron-based catalysts are very attractive targets because iron is the most abundant and least expensive transition metal. We report herein that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions. As an electrocatalyst operating at a current density of −10 mA cm–2, FeP nanoparticles deposited at a mass loading of ∼1 mg cm–2 on Ti substrates exhibited overpotentials of −50 mV in 0.50 M H2SO4 and −102 mV in 1.0 M phosphate buffered saline. The FeP nanoparticles supported sustained hydrogen production with essentially quantitative faradaic yields for extended time periods...
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converting metals into Phosphides a general strategy for the synthesis of metal phosphide nanocrystals
Journal of the American Chemical Society, 2007Co-Authors: Amanda E. Henkes, Yolanda Vasquez, Raymond E. SchaakAbstract:Nanocrystals of metal Phosphides, which can have useful catalytic, electronic, and magnetic properties, are known to be accessible by using trioctylphosphine (TOP) as a highly reactive phosphorus source. Here we report a general strategy for synthesizing transition metal Phosphides, including those with 4d and 5d transition metals that have not previously been reported as unsupported nanocrystals. Unlike previously reported methods that involve direct decomposition of organometallic precursors, our method utilizes preformed metal nanoparticles as templates for generating metal phosphide nanocrystals. Metal nanoparticles are reacted with TOP in a hot solvent (290−360 °C) to form transition metal Phosphides such as Ni2P, PtP2, Rh2P, PdP2, Pd5P2, and Au2P3. Furthermore, nanostructures such as hollow spheres can be easily made using a Kirkendall-type mechanism, which utilizes metal nanoparticles as reactive templates.
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Trioctylphosphine: A General Phosphorus Source for the Low-Temperature Conversion of Metals into Metal Phosphides
Chemistry of Materials, 2007Co-Authors: Amanda E. Henkes, Raymond E. SchaakAbstract:Metal Phosphides can have important properties such as superconductivity, magnetoresistance, magnetocaloric behavior, catalytic activity, and lithium intercalation capacity, which make them useful for a variety of technological applications. Bulk metal Phosphides usually require high temperatures and harsh reaction conditions to form, and metal phosphide nanocrystals can also be challenging to synthesize. Here we elaborate on a recently developed alternative approach for synthesizing metal Phosphides, which involves the solution-mediated reaction of pre-formed metals with trioctylphosphine (TOP) at temperatures below 370 °C. This chemical conversion strategy is shown to be general and highly versatile, successfully forming a wide range of transition-metal and post-transition-metal Phosphides using a range of both bulk and nanoscale metals as precursors. Metal nanocrystals, bulk powders, foils, wires, thin films, lithographically patterned substrates, and supported nanocrystals can all be converted to meta...
Lifeng Liu - One of the best experts on this subject based on the ideXlab platform.
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vapor solid synthesis of monolithic single crystalline cop nanowire electrodes for efficient and robust water electrolysis
Chemical Science, 2017Co-Authors: Xuefei Gao, Dehua Xiong, Fang Xia, Jian Liu, Weiguo Song, Sitaramanjaneya Mouli Thalluri, M F Cerqueira, Lifeng LiuAbstract:Electrochemical water splitting into hydrogen and oxygen is a promising technology for sustainable energy storage. The development of earth-abundant transition metal Phosphides (TMPs) to catalyze the hydrogen evolution reaction (HER) and TMP-derived oxy-hydroxides to catalyze the oxygen evolution reaction (OER) has recently drawn considerable attention. However, most monolithically integrated metal phosphide electrodes are prepared by laborious multi-step methods and their operational stability at high current densities has been rarely studied. Herein, we report a novel vapor–solid synthesis of single-crystalline cobalt phosphide nanowires (CoP NWs) on a porous Co foam and demonstrate their use in overall water splitting. The CoP NWs grown on the entire surface of the porous Co foam ligaments have a large aspect ratio, and hence are able to provide a large catalytically accessible surface over a given geometrical area. Comprehensive investigation shows that under the OER conditions CoP NWs are progressively and conformally converted to CoOOH through electrochemical in situ oxidation/dephosphorization; the latter serving as an active species to catalyze the OER. The in situ oxidized electrode shows exceptional electrocatalytic performance for the OER in 1.0 M KOH, delivering 100 mA cm−2 at an overpotential (η) of merely 300 mV and a small Tafel slope of 78 mV dec−1 as well as excellent stability at various current densities. Meanwhile, the CoP NW electrode exhibits superior catalytic activity for the HER in the same electrolyte, affording −100 mA cm−2 at η = 244 mV and showing outstanding stability. An alkaline electrolyzer composed of two symmetrical CoP NW electrodes can deliver 10 and 100 mA cm−2 at low cell voltages of 1.56 and 1.78 V, respectively. The CoP NW electrolyzer demonstrates exceptional long-term stability for overall water splitting, capable of working at 20 and 100 mA cm−2 for 1000 h without obvious degradation.
Juan F Callejas - One of the best experts on this subject based on the ideXlab platform.
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general strategy for the synthesis of transition metal phosphide films for electrocatalytic hydrogen and oxygen evolution
ACS Applied Materials & Interfaces, 2016Co-Authors: Carlos G Read, Juan F Callejas, Cameron F Holder, Raymond E. SchaakAbstract:Transition metal Phosphides recently have been identified as promising Earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Here, we present a general and scalable strategy for the synthesis of transition metal phosphide electrodes based on the reaction of commercially available metal foils (Fe, Co, Ni, Cu, and NiFe) with various organophosphine reagents. The resulting phosphide electrodes were found to exhibit excellent electrocatalytic HER and OER performance. The most active electrodes required overpotentials of only −128 mV for the HER in acid (Ni2P), −183 mV for the HER in base (Ni2P), and 277 mV for the OER in base (NiFeP) to produce operationally relevant current densities of 10 mA cm–2. Such HER and OER performance compares favorably with samples prepared using significantly more elaborate and costly procedures. Furthermore, we demonstrate that the approach can also be utilized to obtain highly active and conformal metal phosphide coati...
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nanostructured co2p electrocatalyst for the hydrogen evolution reaction and direct comparison with morphologically equivalent cop
Chemistry of Materials, 2015Co-Authors: Juan F Callejas, Carlos G Read, Eric J Popczun, Joshua M Mcenaney, Raymond E. SchaakAbstract:Metal Phosphides have emerged as promising Earth-abundant alternatives to platinum for catalyzing the hydrogen evolution reaction (HER) in acidic aqueous solutions. Here, Co2P nanoparticles having a hollow, multifaceted, crystalline morphology have been evaluated as HER electrocatalysts at a mass loading of 1 mg cm–2 on Ti foil substrates. The Co2P/Ti electrodes required low overpotentials of −95 and −109 mV to produce operationally relevant cathodic current densities of −10 and −20 mA cm–2, respectively. These values establish Co2P nanoparticles as highly active Earth-abundant HER catalyst materials. Importantly, the Co2P nanoparticles are morphologically equivalent to previously reported CoP nanoparticle HER catalysts, allowing a direct side-by-side evaluation of their HER activities. Such comparisons of different metal phosphide HER catalysts with the same constituent elements and morphologies are important for identifying the key materials characteristics that lead to high activity.
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electrocatalytic and photocatalytic hydrogen production from acidic and neutral ph aqueous solutions using iron phosphide nanoparticles
ACS Nano, 2014Co-Authors: Juan F Callejas, Carlos G Read, Eric J Popczun, Joshua M Mcenaney, Chance J Crompton, Adam J Biacchi, Thomas R Gordon, Nathan S Lewis, Raymond E. SchaakAbstract:Nanostructured transition-metal Phosphides have recently emerged as Earth-abundant alternatives to platinum for catalyzing the hydrogen-evolution reaction (HER), which is central to several clean energy technologies because it produces molecular hydrogen through the electrochemical reduction of water. Iron-based catalysts are very attractive targets because iron is the most abundant and least expensive transition metal. We report herein that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions. As an electrocatalyst operating at a current density of −10 mA cm–2, FeP nanoparticles deposited at a mass loading of ∼1 mg cm–2 on Ti substrates exhibited overpotentials of −50 mV in 0.50 M H2SO4 and −102 mV in 1.0 M phosphate buffered saline. The FeP nanoparticles supported sustained hydrogen production with essentially quantitative faradaic yields for extended time periods...
Alexey Shavel - One of the best experts on this subject based on the ideXlab platform.
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Triphenyl Phosphite as the Phosphorus Source for the Scalable and Cost-Effective Production of Transition Metal Phosphides
Chemistry of Materials, 2018Co-Authors: Junfeng Liu, Michaela Meyns, Ting Zhang, Jordi Arbiol, Andreu Cabot, Alexey ShavelAbstract:Transition metal Phosphides have great potential to optimize a number of functionalities in several energy conversion and storage applications, particularly when nanostructured or in nanoparticle form. However, the synthesis of transition metal phosphide nanoparticles and its scalability is often limited by the toxicity, air sensitivity, and high cost of the reagents used. We present here a simple, scalable, and cost-effective “heating up” procedure to produce metal Phosphides using inexpensive, low-toxicity, and air-stable triphenyl phosphite as source of phosphorus and chlorides as metal precursors. This procedure allows the synthesis of a variety of phosphide nanoparticles, including Phosphides of Ni, Co, and Cu. The use of carbonyl metal precursors further allowed the synthesis of Fe2P and MoP nanoparticles. The fact that minor modifications in the experimental parameters allowed producing nanoparticles with different compositions and even to tune their size and shape shows the high potential and vers...
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Triphenyl Phosphite as the Phosphorus Source for the Scalable and Cost-Effective Production of Transition Metal Phosphides
2018Co-Authors: Junfeng Liu, Michaela Meyns, Ting Zhang, Jordi Arbiol, Andreu Cabot, Alexey ShavelAbstract:Transition metal Phosphides have great potential to optimize a number of functionalities in several energy conversion and storage applications, particularly when nanostructured or in nanoparticle form. However, the synthesis of transition metal phosphide nanoparticles and its scalability is often limited by the toxicity, air sensitivity, and high cost of the reagents used. We present here a simple, scalable, and cost-effective “heating up” procedure to produce metal Phosphides using inexpensive, low-toxicity, and air-stable triphenyl phosphite as source of phosphorus and chlorides as metal precursors. This procedure allows the synthesis of a variety of phosphide nanoparticles, including Phosphides of Ni, Co, and Cu. The use of carbonyl metal precursors further allowed the synthesis of Fe2P and MoP nanoparticles. The fact that minor modifications in the experimental parameters allowed producing nanoparticles with different compositions and even to tune their size and shape shows the high potential and versatility of the triphenyl phosphite precursor and the presented method. We also detail here a methodology to displace organic ligands from the surface of phosphide nanoparticles, which is a key step toward their application in energy conversion and storage systems
Carlos G Read - One of the best experts on this subject based on the ideXlab platform.
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general strategy for the synthesis of transition metal phosphide films for electrocatalytic hydrogen and oxygen evolution
ACS Applied Materials & Interfaces, 2016Co-Authors: Carlos G Read, Juan F Callejas, Cameron F Holder, Raymond E. SchaakAbstract:Transition metal Phosphides recently have been identified as promising Earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Here, we present a general and scalable strategy for the synthesis of transition metal phosphide electrodes based on the reaction of commercially available metal foils (Fe, Co, Ni, Cu, and NiFe) with various organophosphine reagents. The resulting phosphide electrodes were found to exhibit excellent electrocatalytic HER and OER performance. The most active electrodes required overpotentials of only −128 mV for the HER in acid (Ni2P), −183 mV for the HER in base (Ni2P), and 277 mV for the OER in base (NiFeP) to produce operationally relevant current densities of 10 mA cm–2. Such HER and OER performance compares favorably with samples prepared using significantly more elaborate and costly procedures. Furthermore, we demonstrate that the approach can also be utilized to obtain highly active and conformal metal phosphide coati...
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nanostructured co2p electrocatalyst for the hydrogen evolution reaction and direct comparison with morphologically equivalent cop
Chemistry of Materials, 2015Co-Authors: Juan F Callejas, Carlos G Read, Eric J Popczun, Joshua M Mcenaney, Raymond E. SchaakAbstract:Metal Phosphides have emerged as promising Earth-abundant alternatives to platinum for catalyzing the hydrogen evolution reaction (HER) in acidic aqueous solutions. Here, Co2P nanoparticles having a hollow, multifaceted, crystalline morphology have been evaluated as HER electrocatalysts at a mass loading of 1 mg cm–2 on Ti foil substrates. The Co2P/Ti electrodes required low overpotentials of −95 and −109 mV to produce operationally relevant cathodic current densities of −10 and −20 mA cm–2, respectively. These values establish Co2P nanoparticles as highly active Earth-abundant HER catalyst materials. Importantly, the Co2P nanoparticles are morphologically equivalent to previously reported CoP nanoparticle HER catalysts, allowing a direct side-by-side evaluation of their HER activities. Such comparisons of different metal phosphide HER catalysts with the same constituent elements and morphologies are important for identifying the key materials characteristics that lead to high activity.
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electrocatalytic and photocatalytic hydrogen production from acidic and neutral ph aqueous solutions using iron phosphide nanoparticles
ACS Nano, 2014Co-Authors: Juan F Callejas, Carlos G Read, Eric J Popczun, Joshua M Mcenaney, Chance J Crompton, Adam J Biacchi, Thomas R Gordon, Nathan S Lewis, Raymond E. SchaakAbstract:Nanostructured transition-metal Phosphides have recently emerged as Earth-abundant alternatives to platinum for catalyzing the hydrogen-evolution reaction (HER), which is central to several clean energy technologies because it produces molecular hydrogen through the electrochemical reduction of water. Iron-based catalysts are very attractive targets because iron is the most abundant and least expensive transition metal. We report herein that iron phosphide (FeP), synthesized as nanoparticles having a uniform, hollow morphology, exhibits among the highest HER activities reported to date in both acidic and neutral-pH aqueous solutions. As an electrocatalyst operating at a current density of −10 mA cm–2, FeP nanoparticles deposited at a mass loading of ∼1 mg cm–2 on Ti substrates exhibited overpotentials of −50 mV in 0.50 M H2SO4 and −102 mV in 1.0 M phosphate buffered saline. The FeP nanoparticles supported sustained hydrogen production with essentially quantitative faradaic yields for extended time periods...