Phase transfer-based high-efficiency recycling of precious metal electrocatalysts

Recycling precious metals with high-efficiency is undoubtedly beneficial to optimize resource utilization for environmental remediation and sustainable development. Herein, we report an efficient route to recycle the palladium (Pd) and platinum (Pt) electrocatalysts using a phase transfer method. This strategy involves acidic dissolution of deactivated precious metal (Pd/Pt) electrocatalysts from their loading substrates, mixing with an ethanolic solution of dodecylamine (DDA), subsequent extraction of metal ions into a non-polar organic phase, and final reduction by sodium borohydride to reproduce high-performance electrocatalysts towards typical electrochemical reactions, e.g., oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR). In specific, the transfer efficiencies are up to 98% and the final recovery rate is over 85% for Pd and Pt electrocatalysts in each cycle. This approach symbolizes a facile and efficient way to recover precious metals, which might be applied to recycling a wide range of metals in various realms after appropriate modifications

Sulfur fate during in-situ gasification chemical looping combustion (iG-CLC) of coal

Sulfur conversion during in-situ gasification chemical looping combustion (iG-CLC) of coal is consisted by pyrolysis and char gasification. Insight into the fate of sulfur in these two processes is essential for exploring appropriate strategies for sulfur emission control, whereas in most of works the pyrolysis and gasification could not be fully identified. In this case, a two-stage fluidized bed reactor system comprising a lower and a higher reactor was used to generate in-situ and separate gases from pyrolysis and gasification in this work. Sulfurous gases including H2S, COS, CS2 and SO2 were experimentally studied under various conditions by changing operation temperature (T), O/fuel ratio (Φ) and OC reduction degree (XOC), while the solid samples were regularly collected for the characterization using different techniques. It was found that the sol-gel Fe2O3/Al2O3 was a sulfur resistant OC during the iG-CLC process, thus no formation of sulfur components in the material. The values of T and Φ have positive effect on the conversion of sulfurous gases to SO2, whereas a lower XOC value can improve the conversion of H2S. The main components from volatiles (mainly H2S and CS2) and from char (mainly COS) can be effectively converted to SO2 by the OC material. The coal ash exhibited a desulfurization function, as some sulfur contents were retained as CaSO4 during the iG-CLC tests. Finally, the fate of sulfur in coal during iG-CLC was comprehensively mapped, which would be significant for developing strategies for sulfur emission control

Introducing High-Valence Iridium Single Atoms into Bimetal Phosphides toward High-Efficiency Oxygen Evolution and Overall Water Splitting

Single atoms are superior electrocatalysts having high atomic utilization and amazing activity for water oxidation and splitting. Herein, this work reports a thermal reduction method to introduce high-valence iridium (Ir) single atoms into bimetal phosphide (FeNiP) nanoparticles toward high-efficiency oxygen evolution reaction (OER) and overall water splitting. The presence of high-valence single Ir atoms (Ir4+) and their synergistic interaction with Ni3+ species as well as the disproportionation of Ni3+ assisted by Fe collectively contribute to the exceptional OER performance. In specific, at appropriate Ir/Ni and Fe/Ni ratios, the as-prepared Ir-doped FeNiP (Ir-25-Fe16Ni100P64) nanoparticles at a mass loading of only 35 mu g cm(-2) show the overpotential as low as 232 mV at 10 mA cm(-2) and activity as high as 1.86 A mg(-1) at 1.5 V versus RHE for OER in 1.0 m KOH. Computational simulations confirm the vital role of high-valence Ir to weaken the adsorption of OER intermediates, favorable for accelerating OER kinetics. Impressively, a Pt/C||Ir-25-Fe16Ni100P64 two-electrode alkaline electrolyzer affords a current density of 10 mA cm(-2) at a low cell voltage of 1.42 V, along with satisfied stability. An AA battery with a nominal voltage of 1.5 V can drive overall water splitting with obvious bubbles released

Introducing High-Valence Iridium Single Atoms into Bimetal Phosphides toward High-Efficiency Oxygen Evolution and Overall Water Splitting

Single atoms are superior electrocatalysts having high atomic utilization and amazing activity for water oxidation and splitting. Herein, this work reports a thermal reduction method to introduce high-valence iridium (Ir) single atoms into bimetal phosphide (FeNiP) nanoparticles toward high-efficiency oxygen evolution reaction (OER) and overall water splitting. The presence of high-valence single Ir atoms (Ir4+) and their synergistic interaction with Ni3+ species as well as the disproportionation of Ni3+ assisted by Fe collectively contribute to the exceptional OER performance. In specific, at appropriate Ir/Ni and Fe/Ni ratios, the as-prepared Ir-doped FeNiP (Ir-25-Fe16Ni100P64) nanoparticles at a mass loading of only 35 mu g cm(-2) show the overpotential as low as 232 mV at 10 mA cm(-2) and activity as high as 1.86 A mg(-1) at 1.5 V versus RHE for OER in 1.0 m KOH. Computational simulations confirm the vital role of high-valence Ir to weaken the adsorption of OER intermediates, favorable for accelerating OER kinetics. Impressively, a Pt/C||Ir-25-Fe16Ni100P64 two-electrode alkaline electrolyzer affords a current density of 10 mA cm(-2) at a low cell voltage of 1.42 V, along with satisfied stability. An AA battery with a nominal voltage of 1.5 V can drive overall water splitting with obvious bubbles released

CoSe2/MoS2 Heterostructures to Couple Polysulfide Adsorption and Catalysis in Lithium-Sulfur Batteries(dagger)

Main observation and conclusion Lithium-sulfur batteries have been regarded as one of most promising next-generation energy storage devices because of their high energy density and low cost. However, polysulfide shuttling and slow kinetics hinder the practical application. We fabricated hierarchically heterostructured CoSe2/MoS2 nanoarrays on carbon clothes as the sulfur cathode host. The resulting heterostructures facilitate electron conduction and improve electrolyte wetting. More importantly, the composite heterostructures couple the strong polysulfide adsorption of CoSe2 and high catalytic activity of MoS2 to synergistically accelerate polysulfide conversion, demonstrating higher catalytic activity than their individual components

CoSe2/MoS2 Heterostructures to Couple Polysulfide Adsorption and Catalysis in Lithium-Sulfur Batteries(dagger)

Main observation and conclusion Lithium-sulfur batteries have been regarded as one of most promising next-generation energy storage devices because of their high energy density and low cost. However, polysulfide shuttling and slow kinetics hinder the practical application. We fabricated hierarchically heterostructured CoSe2/MoS2 nanoarrays on carbon clothes as the sulfur cathode host. The resulting heterostructures facilitate electron conduction and improve electrolyte wetting. More importantly, the composite heterostructures couple the strong polysulfide adsorption of CoSe2 and high catalytic activity of MoS2 to synergistically accelerate polysulfide conversion, demonstrating higher catalytic activity than their individual components

A Magnesium/Lithium Hybrid-Ion Battery with Modified All-Phenyl-Complex-Based Electrolyte Displaying Ultralong Cycle Life and Ultrahigh Energy Density

Magnesium/lithium hybrid-ion batteries (MLHBs) combine the advantages of high safety and fast ionic kinetics, which enable them to be promising emerging energy-storage systems. Here, a high-performance MLHB using a modified all-phenyl complex with a lithium bis(trifluoromethanesulfonyl)imide electrolyte and a NiCo2S4 cathode on a copper current collector is developed. A reversible conversion involving a copper collector with NiCo2S4 efficiently avoids the electrolyte dissociation and diffusion difficulties of Mg2+ ions, enabling low polarization and fast redox, which is verified by X-ray absorption near edge structure analysis. Such combination affords the best MLHB among all those ever reported, with a reversible capacity of 204.7 mAh g(-1) after 2600 cycles at 2.0 A g(-1), and delivers an ultrahigh full electrode-basis energy density of 708 Wh kg(-1). The developed MLHB also achieves good rate performance and temperature tolerance at -10 and 50 degrees C with a low electrolyte consumption. The hybrid-ion battery system presented here could inspire a broad set of engineering potentials for high-safety battery technologies and beyond

A Magnesium/Lithium Hybrid-Ion Battery with Modified All-Phenyl-Complex-Based Electrolyte Displaying Ultralong Cycle Life and Ultrahigh Energy Density

Magnesium/lithium hybrid-ion batteries (MLHBs) combine the advantages of high safety and fast ionic kinetics, which enable them to be promising emerging energy-storage systems. Here, a high-performance MLHB using a modified all-phenyl complex with a lithium bis(trifluoromethanesulfonyl)imide electrolyte and a NiCo2S4 cathode on a copper current collector is developed. A reversible conversion involving a copper collector with NiCo2S4 efficiently avoids the electrolyte dissociation and diffusion difficulties of Mg2+ ions, enabling low polarization and fast redox, which is verified by X-ray absorption near edge structure analysis. Such combination affords the best MLHB among all those ever reported, with a reversible capacity of 204.7 mAh g(-1) after 2600 cycles at 2.0 A g(-1), and delivers an ultrahigh full electrode-basis energy density of 708 Wh kg(-1). The developed MLHB also achieves good rate performance and temperature tolerance at -10 and 50 degrees C with a low electrolyte consumption. The hybrid-ion battery system presented here could inspire a broad set of engineering potentials for high-safety battery technologies and beyond

Catalytic Amination of Polylactic Acid to Alanine

In comparison to the traditional petroleum-based plastics, polylactic acid, the most popular biodegradable plastic, can be decomposed into carbon dioxide and water in the environment. However, the natural degradation of polylactic acid requires a substantial period of time and, more importantly, it is a carbon-emitting process. Therefore, it is highly desirable to develop a novel transformation process that can upcycle the plastic trash into value-added products, especially with high chemical selectivity. Here we demonstrate a one-pot catalytic method to convert polylactic acid into alanine by a simple ammonia solution treatment using a Ru/TiO2 catalyst. The process has a 77% yield of alanine at 140 degrees C, and an overall selectivity of 94% can be reached by recycling experiments. Importantly, no added hydrogen is used in this process. It has been verified that lactamide and ammonium lactate are the initial intermediates and that the dehydrogenation of ammonium lactate initiates the amination, while Ru nanoparticles are essential for the dehydrogenation/rehydrogenation and amination steps. The process demonstrated here could expand the application of polylactic acid waste and inspire new upcycling strategies for different plastic wastes