Self-Limited Formation of Cobalt Nanoparticles for Spontaneous Hydrogen Production through Hydrazine Electrooxidation.

Hydrogen (H2 ) has emerged as a highly promising energy carrier owing to its remarkable energy density and carbon emission-free properties. However, the widespread application of H2 fuel has been limited by the difficulty of storage. In this work, spontaneous electrochemical hydrogen production is demonstrated using hydrazine (N2 H4 ) as a liquid hydrogen storage medium and enabled by a highly active Co catalyst for hydrazine electrooxidation reaction (HzOR). The HzOR electrocatalyst is developed by a self-limited growth of Co nanoparticles from a Co-based zeolitic imidazolate framework (ZIF), exhibiting abundant defective surface atoms as active sites for HzOR. Notably, these self-limited Co nanoparticles exhibit remarkable HzOR activity with a negative working potential of -0.1 V (at 10 mA cm-2 ) in 0.1 m N2 H4 /1 m KOH electrolyte. Density functional theory (DFT) calculations are employed to validate the superior performance of low-coordinated Co active sites in facilitating HzOR. By taking advantage of the potential difference between HzOR and the hydrogen evolution reaction (HER), a novel HzOR||HER electrochemical system is developed to spontaneously produce H2 without external energy input. Overall, the work offers valuable guidance for developing active HzOR catalyst. The novel HzOR||HER electrochemical system represents a promising and innovative solution for energy-efficient hydrogen production.

Electrochemical Hydrophobic Tri-layer Interface Rendered Mechanically Graded Solid Electrolyte Interface for Stable Zinc Metal Anode.

The aqueous zinc-ion battery is promising as grid scale energy storage device, but hindered by the instable electrode/electrolyte interface. Herein, we report the lean-water ionic liquid electrolyte for aqueous zinc metal batteries. The lean-water ionic liquid electrolyte creates the hydrophobic tri-layer interface assembled by first two layers of hydrophobic OTF- and EMIM+ and third layer of loosely attached water, beyond the classical Gouy-Chapman-Stern theory based electrochemical double layer. By taking advantage of the hydrophobic tri-layer interface, the lean-water ionic liquid electrolyte enables a wide electrochemical working window (2.93 V) with relatively high zinc ion conductivity (17.3 mS/cm). Furthermore, the anion crowding interface facilitates the OTF- decomposition chemistry to create the mechanically graded solid electrolyte interface layer to simultaneously suppress the dendrite formation and maintain the mechanical stability. In this way, the lean-water based ionic liquid electrolyte realizes the ultralong cyclability of over 10000 cycles at 20 A/g and at practical condition of N/P ratio of 1.5, the cumulated areal capacity reach 1.8 Ah/cm2 , which outperforms the state-of-the-art zinc metal battery performance. Our work highlights the importance of the stable electrode/electrolyte interface stability, which would be practical for building high energy grid scale zinc-ion battery.

Fluoride-Rich, Organic-Inorganic Gradient Interphase Enabled by Sacrificial Solvation Shells for Reversible Zinc Metal Batteries.

Zinc metal batteries are strongly hindered by water corrosion, as solvated zinc ions would bring the active water molecules to the electrode/electrolyte interface constantly. Herein, we report a sacrificial solvation shell to repel active water molecules from the electrode/electrolyte interface and assist in forming a fluoride-rich, organic-inorganic gradient solid electrolyte interface (SEI) layer. The simultaneous sacrificial process of methanol and Zn(CF3SO3)2 results in the gradient SEI layer with an organic-rich surface (CH2OC- and C5 product) and an inorganic-rich (ZnF2) bottom, which combines the merits of fast ion diffusion and high flexibility. As a result, the methanol additive enables corrosion-free zinc stripping/plating on copper foils for 300 cycles with an average coulombic efficiency of 99.5%, a record high cumulative plating capacity of 10 A h/cm2 at 40 mA/cm2 in Zn/Zn symmetrical batteries. More importantly, at an ultralow N/P ratio of 2, the practical VO2//20 µm thick Zn plate full batteries with a high areal capacity of 4.7 mAh/cm2 stably operate for over 250 cycles, establishing their promising application for grid-scale energy storage devices. Furthermore, directly utilizing the 20 µm thick Zn for the commercial-level areal capacity (4.7 mAh/cm2) full zinc battery in our work would simplify the manufacturing process and boost the development of the commercial zinc battery for stationary storage.

Proton Storage in Metallic H1.75MoO3 Nanobelts through the Grotthuss Mechanism.

The proton, as the cationic form of the lightest element-H, is regarded as most ideal charge carrier in "rocking chair" batteries. However, current research on proton batteries is still at its infancy, and they usually deliver low capacity and suffer from severe acidic corrosion. Herein, electrochemically activated metallic H1.75MoO3 nanobelts are developed as a stable electrode for proton storage. The electrochemically pre-intercalated protons not only bond directly with the terminal O3 site via strong O-H bonds but also interact with the oxygens within the adjacent layers through hydrogen bonding, forming a hydrogen-bonding network in H1.75MoO3 nanobelts and enabling a diffusion-free Grotthuss mechanism as a result of its ultralow activation energy of ∼0.02 eV. To the best of our knowledge, this is the first reported inorganic electrode exhibiting Grotthuss mechanism-based proton storage. Additionally, the proton intercalation into MoO3 with formation of H1.75MoO3 induces strong Jahn-Teller electron-phonon coupling, rendering a metallic state. As a consequence, the H1.75MoO3 shows an outstanding fast charging performance and maintains a capacity of 111 mAh/g at 2500 C, largely outperforming the state-of-art battery electrodes. More importantly, a symmetric proton ion full cell based on H1.75MoO3 was assembled and delivered an energy density of 14.7 Wh/kg at an ultrahigh power density of 12.7 kW/kg, which outperforms those of fast charging supercapacitors and lead-acid batteries.

A facile surface alloy-engineering route to enable robust lithium metal anodes.

Li-rich alloys have been developed as advanced artificial SEI layers to suppress the formation of Li dendrites and parasitic reactions on the Li metal anode. Here, we systematically investigated the role of Li-rich alloys on Li deposition and decomposition of electrolyte molecules by DFT simulations. We found that the alloy surfaces exhibit self-smoothing behavior for suppressing the nucleation of lithium dendrites. This behavior is derived from the surface-localized free electrons (namely, the localized Li-affinity) of the Li-rich alloy SEI surfaces. Furthermore, the electron transfer between the electrolyte molecules and anode surface was efficiently reduced by the Li-rich alloys. The Li-rich alloys with low Li s states at the Fermi level and the high surface work function exhibit low reducibility to the electrolytes. Our findings herein provide a systematical understanding of Li-rich alloy functional layers, which are of great significance for advanced Li metal batteries.

How well does XAD resin extraction recover halogenated disinfection byproducts for comprehensive identification and toxicity testing?

Halogenated disinfection byproducts (DBPs) are an unintended consequence of drinking water disinfection, and can have significant toxicity. XAD resins are commonly used to extract and enrich trace levels of DBPs for comprehensive, nontarget identification of DBPs and also for in vitro toxicity studies. However, XAD resin recoveries for complete classes of halogenated DBPs have not been evaluated, particularly for low, environmentally relevant levels (ng/L to low µg/L). Thus, it is not known whether levels of DBPs or the toxicity of drinking water might be underestimated. In this study, DAX-8/XAD-2 layered resins were evaluated, considering both adsorption and elution from the resins, for extracting 66 DBPs from water. Results demonstrate that among the 7 classes of DBPs investigated, trihalomethanes (THMs), including iodo-THMs, were the most efficiently adsorbed, with recovery of most THMs ranging from 50%-96%, followed by halonitromethanes (40%-90%). The adsorption ability of XAD resins for haloacetonitriles, haloacetamides, and haloacetaldehydes was highly dependent on the individual species. The adsorption capacity of XAD resins for haloacetic acids was lower (5%-48%), even after adjusting to pH 1 before extraction. Recovery efficiency for most DBPs was comparable with their adsorption, as most were eluted effectively from XAD resins by ethyl acetate. DBP polarity and molecular weight were the two most important factors that determine their recovery. Recovery of trichloromethane, iodoacetic acid, chloro- and iodo-acetonitrile, and chloroacetamide were among the lowest, which could lead to underestimation of toxicity, particularly for iodoacetic acid and iodo-acetonitrile, which are highly toxic.

A Durable Ni-Zn Microbattery with Ultrahigh-Rate Capability Enabled by In Situ Reconstructed Nanoporous Nickel with Epitaxial Phase.

Powering device for miniaturized electronics is highly desired with well-maintained capacity and high-rate performance. Though Ni-Zn microbattery can meet the demand to some extent with intrinsic fast kinetic, it still suffers irreversible structure degradation due to the repeated lattice strain. Herein, a stable Ni-Zn microbattery with ultrahigh-rate performance is rationally constructed through in situ electrochemical approaches, including the reconstruction of nanoporous nickel and the introduction of epitaxial Zn(OH)2 nanophase. With the enhanced ionic adsorption effect, the superior reactivity of the superficial nickel-based nanostructure is well stabilized. Based on facile miniaturization and electrochemical techniques, the fabricated nickel microelectrode exhibits 63.8% capacity retention when the current density is 500 times folded, and the modified hydroxides contribute to the great stability of the porous structure (92% capacity retention after 10 000 cycles). Furthermore, when the constructed Ni-Zn microbattery is measured in a practical metric, excellent power density (320.17 mW cm-2 ) and stable fast-charging performance (over 90% capacity retention in 3500 cycles) are obtained. This surface reconstruction strategy for nanostructure provides a new direction for the optimization of electrode structure and enriches high-performance output units for integrated microelectronics.

Wearable Textile-Based Co-Zn Alkaline Microbattery with High Energy Density and Excellent Reliability.

Wearable in-plane Zn-based microbatteries are considered as promising micropower sources for wearable electronics due to their high capacity, low cost, high safety, and easy integration. However, their applications are severely impeded by inadequate energy density arising from unsatisfactory capacity of cathode and poor cycling stability caused by degradation of electrode materials and Zn dendrite. Additionally, the short-circuit induced safety issue caused by Zn dendrite is still a roadblock for Zn-based microbatteries. Herein, a textile-based Co-Zn microbattery with ultrahigh energy density and excellent cycling stability is demonstrated. Benefiting from the fast electron transport of three-dimensional (3D) porous Ni-coated textile and synergistic effect from the hierarchical Co(OH)2 @NiCo layered double hydroxide (LDH) core-shell electrode, the fabricated Co-Zn microbattery with high flexibility delivers superior energy/power densities of 0.17 mWh cm-2 /14.4 mW cm-2 , outperforming most reported micro energy storage devices. Besides, the trench-type configuration as well as the 3D porous Zn@carbon clothes can avoid the short-circuit-induced safety issues, resulting in excellent cycling stability (71% after 800 cycles). The unique core-shell structure and novel configuration provide a brand-new design strategy for high-performance wearable in-plane microdevices.

3D Nitrogen-Doped Graphene Encapsulated Metallic Nickel-Iron Alloy Nanoparticles for Efficient Bifunctional Oxygen Electrocatalysis.

Invited for the cover of this issue is Liqiang Mai and co-workers at Wuhan University of Technology. The image depicts Ni3 Fe alloy nanoparticles encapsulated in N-doped graphene as an efficient bifunctional oxygen electrocatalyst toward rechargeable Zn-air batteries, which is expected to drive the electric vehicle. Read the full text of the article at 10.1002/chem.201904722.

3D Nitrogen-Doped Graphene Encapsulated Metallic Nickel-Iron Alloy Nanoparticles for Efficient Bifunctional Oxygen Electrocatalysis.

It is extremely desirable to explore high-efficient, affordable and robust oxygen electrocatalysts toward rechargeable Zn-air batteries (ZABs). A 3D porous nitrogen-doped graphene encapsulated metallic Ni3 Fe alloy nanoparticles aerogel (Ni3 Fe-GA1 ) was constructed through a facile hydrothermal assembly and calcination process. Benefiting from 3D porous configuration with great accessibility, high electrical conductivity, abundant active sites, optimal nitrogen content and strong electronic interactions at the Ni3 Fe/N-doped graphene heterointerface, the obtained aerogel showed outstanding catalytic performance toward the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Specifically, it exhibited an overpotential of 239 mV to attain 10 mA cm-2 for OER, simultaneously providing a positive onset potential of 0.93 V within a half-wave potential of 0.8 V for ORR. Accordingly, when employed in the aqueous ZABs, Ni3 Fe-GA1 achieved higher power density and superior reversibility than Pt/C-IrO2 catalyst, making it a potential candidate for rechargeable ZABs.

Langmuir-Blodgett Nanowire Devices for In Situ Probing of Zinc-Ion Batteries.

In situ monitoring the evolution of electrode materials in micro/nano scale is crucial to understand the intrinsic mechanism of rechargeable batteries. Here a novel on-chip Langmuir-Blodgett nanowire (LBNW) microdevice is designed based on aligned and assembled MnO2 nanowire quasimonolayer films for directly probing Zn-ion batteries (ZIBs) in real-time. With an interdigital device configuration, a splendid Ohmic contact between MnO2 LBNWs and pyrolytic carbon current collector is demonstrated here, enabling a small polarization voltage. In addition, this work reveals, for the first time, that the conductance of MnO2 LBNWs monotonically increases/decreases when the ZIBs are charged/discharged. Multistep phase transition is mainly responsible for the mechanism of the ZIBs, as evidenced by combined high-resolution transmission electron microscopy and in situ Raman spectroscopy. This work provides a new and adaptable platform for microchip-based in situ simultaneous electrochemical and physical detection of batteries, which would promote the fundamental and practical research of nanowire electrode materials in energy storage applications.

Superior Hydrogen Evolution Reaction Performance in 2H-MoS2 to that of 1T Phase.

In the hydrogen evolution reaction (HER), energy-level matching is a prerequisite for excellent electrocatalytic activity. Conventional strategies such as chemical doping and the incorporation of defects underscore the complicated process of controlling the doping species and the defect concentration, which obstructs the understanding of the function of band structure in HER catalysis. Accordingly, 2H-MoS2 and 1T-MoS2 are used to create electrocatalytic nanodevices to address the function of band structure in HER catalysis. Interestingly, it is found that the 2H-MoS2 with modulated Fermi level under the application of a vertical electric field exhibits excellent electrocatalytic activity (as evidenced by an overpotential of 74 mV at 10 mA cm-2 and a Tafel slope of 99 mV per decade), which is superior to 1T-MoS2 . This unexpected excellent HER performance is ascribed to the fact that electrons are injected into the conduction band under the condition of back-gate voltage, which leads to the increased Fermi level of 2H-MoS2 and a shorter Debye screen length. Hence, the required energy to drive electrons from the electrocatalyst surface to reactant will decrease, which activates the 2H-MoS2 thermodynamically.

Strongly Coupled Pyridine-V2 O5 ·nH2 O Nanowires with Intercalation Pseudocapacitance and Stabilized Layer for High Energy Sodium Ion Capacitors.

Developing pseudocapacitive cathodes for sodium ion capacitors (SICs) is very significant for enhancing energy density of SICs. Vanadium oxides cathodes with pseudocapacitive behavior are able to offer high capacity. However, the capacity fading caused by the irreversible collapse of layer structure remains a major issue. Herein, based on the Acid-Base Proton theory, a strongly coupled layered pyridine-V2 O5 ·nH2 O nanowires cathode is reported for highly efficient sodium ion storage. By density functional theory calculations, in situ X-ray diffraction, and ex situ Fourier-transform infrared spectroscopy, a strong interaction between protonated pyridine and VO group is confirmed and stable during cycling. The pyridine-V2 O5 ·nH2 O nanowires deliver long-term cyclability (over 3000 cycles), large pseudocapacitive behavior (78% capacitive contribution at 1 mV s-1 ) and outstanding rate capability. The assembled pyridine-V2 O5 ·nH2 O//graphitic mesocarbon microbead SIC delivers high energy density of ≈96 Wh kg-1 (at 59 W kg-1 ) and power density of 14 kW kg-1 (at 37.5 Wh kg-1 ). The present work highlights the strategy of realizing strong interaction in the interlayer of V2 O5 ·nH2 O to enhance the electrochemical performance of vanadium oxides cathodes. The strategy could be extended for improving the electrochemical performance of other layered materials.

Extrapolation of high-order correlation energies: the WMS model.

We have developed a new composite model chemistry method called WMS (Wuhan-Minnesota scaling method) with three characteristics: (1) a composite scheme to approximate the complete configuration interaction valence energy with the affordability condition of requiring no calculation more expensive than CCSD(T)/jul-cc-pV(T+d)Z, (2) low-cost methods for the inner-shell correlation contribution and scalar relativistic correction, and (3) accuracy comparable to methods with post-CCSD(T) components. The new method is shown to be accurate for the W4-17 database of 200 atomization energies with an average mean unsigned error (averaged with equal weight over strongly correlated and weakly correlated subsets of the data) of 0.45 kcal mol-1, and the performance/cost ratio of these results compares very favorably to previously available methods. We also assess the WMS method against the DBH24-W4 database of diverse barrier heights and the energetics of the reactions of three strongly correlated Criegee intermediates with water. These results demonstrate that higher-order correlation contributions necessary to obtain high accuracy for molecular thermochemistry may be successfully extrapolated from the lower-order components of CCSD(T) calculations, and chemical accuracy can now be obtained for larger and more complex molecules and reactions.

Field-Effect Tuned Adsorption Dynamics of VSe2 Nanosheets for Enhanced Hydrogen Evolution Reaction.

Transition metal dichalcogenides, such as MoS2 and VSe2 have emerged as promising catalysts for the hydrogen evolution reaction (HER). Substantial work has been devoted to optimizing the catalytic performance by constructing materials with specific phases and morphologies. However, the optimization of adsorption/desorption process in HER is rare. Herein, we concentrate on tuning the dynamics of the adsorption process in HER by applying a back gate voltage to the pristine VSe2 nanosheet. The back gate voltage induces the redistribution of the ions at the electrolyte-VSe2 nanosheet interface, which realizes the enhanced electron transport process and facilitates the rate-limiting step (discharge process) under HER conditions. A considerable low onset overpotential of 70 mV is achieved in VSe2 nanosheets without any chemical treatment. Such unexpected improvement is attributed to the field tuned adsorption-dynamics of VSe2 nanosheet, which is demonstrated by the greatly optimized charge transfer resistance (from 1.03 to 0.15 MΩ) and time constant of the adsorption process (from 2.5 × 10-3 to 5.0 × 10-4 s). Our results demonstrate enhanced catalysis performance in the VSe2 nanosheet by tuning the adsorption dynamics with a back gate, which provides new directions for improving the catalytic activity of non-noble materials.

Carbon-MEMS-Based Alternating Stacked MoS2 @rGO-CNT Micro-Supercapacitor with High Capacitance and Energy Density.

A novel process to fabricate a carbon-microelectromechanical-system-based alternating stacked MoS2 @rGO-carbon-nanotube (CNT) micro-supercapacitor (MSC) is reported. The MSC is fabricated by successively repeated spin-coating of MoS2 @rGO/photoresist and CNT/photoresist composites twice, followed by photoetching, developing, and pyrolysis. MoS2 @rGO and CNTs are embedded in the carbon microelectrodes, which cooperatively enhance the performance of the MSC. The fabricated MSC exhibits a high areal capacitance of 13.7 mF cm-2 and an energy density of 1.9 µWh cm-2 (5.6 mWh cm-3 ), which exceed many reported carbon- and MoS2 -based MSCs. The MSC also retains 68% of capacitance at a current density of 2 mA cm-2 (5.9 A cm-3 ) and an outstanding cycling performance (96.6% after 10 000 cycles, at a scan rate of 1 V s-1 ). Compared with other MSCs, the MSC in this study is fabricated by a low-cost and facile process, and it achieves an excellent and stable electrochemical performance. This approach could be highly promising for applications in integration of micro/nanostructures into microdevices/systems.

[Development of Modern Medical Equipment Management System Based on Web].

Under the concept of Internet+, this paper proposed modern medical equipment management system, which could satisfy our hospital and also agree with the evaluation of 3A hospital. The system can monitor, analyze and effectively manage the whole life of the equipment that included assembly, use, maintenance, update and rejection. The system mainly includes eleven modules that are equipment management, repair management, online-repair management, PM management, metering management, benefit analysis, guarantee management, supporter management, barcode management, inventory management and inspection management. The system could help to manage medical equipment effectively and optimize resource a location.

Antibiotic sulfanilamide biodegradation by acclimated microbial populations.

Sulfonamide antibiotics are commonly detected in the environment. Microbial degradation can play an important role in the dissipation of sulfonamide antibiotics. However, many aspects regarding the influential factor and biodegradation pathway remain essentially unclear. Moreover, phylogenetic information on the sulfonamide-degrading microbial community is still very limited. The present study investigated the biodegradation of sulfonamide antibiotic sulfanilamide by acclimated mixed culture and its influential factors, and the sulfanilamide-degrading microbial community. At the initial sulfanilamide concentration of 100 µg/L, nearly half of the antibiotic could be removed by acclimated microbial populations after 1 week of incubation, and an average removal rate of 78.3 % could be achieved in 4 weeks. p-Phenylenediamine, benzene sulfonamide, and hydroxylamine benzene sulfonamide were identified as the potential intermediates. Sulfanilamide biodegradation could be enhanced by a temperature rise and the presence of external carbon or nitrogen sources. The richness, diversity, and structure of the bacterial community showed a remarkable change with sulfanilamide biodegradation. Firmicutes and Bacteroidetes (mainly represented by classes Bacilli and Flavobacteriia) dominated the sulfanilamide-degrading bacterial community.

Sorption and desorption of organic matter on solid-phase extraction media to isolate and identify N-nitrosodimethylamine precursors.

#x02010;Nitrosodimethylamine is mutagenic in rodents, a drinking water contaminant, and a byproduct of drinking water disinfection by chloramination. Nitrosodimethylamine precursor identification leads to their control and improved understanding of nitrosodimethylamine formation during chloramination. Mass balances on nitrosodimethylamine precursors were evaluated across solid-phase extraction cartridges and in eluates to select the best combination of solid-phase media and eluent that maximized recovery of nitrosodimethylamine precursors into a solvent amenable to time-of-flight mass spectrometry analysis. After reviewing literature and comparing various solid-phase cartridges and eluent combinations, a method was obtained to efficiently recover nitrosodimethylamine precursors. The approach with the greatest recoveries of nitrosodimethylamine precursors involved cation exchange resin loaded with water samples at pH 3 and eluted with 5% NH4 OH in methanol. This indicated that nitrosodimethylamine precursors are amines that protonate at low pH and deprotonate at high pH. Quaternary amines were irreversibly sorbed to the cation exchange cartridge and did not account for a large fraction of precursors. Overall, a median recovery of 82% for nitrosodimethylamine precursors was achieved from 11 surface waters and one wastewater. Applying this method allowed discovery of methadone as a new nitrosodimethylamine precursor in wastewater effluent and drinking water treatment plant intakes.

Toluene decomposition performance and NOx by-product formation during a DBD-catalyst process.

Characteristics of toluene decomposition and formation of nitrogen oxide (NOx) by-products were investigated in a dielectric barrier discharge (DBD) reactor with/without catalyst at room temperature and atmospheric pressure. Four kinds of metal oxides, i.e., manganese oxide (MnOx), iron oxide (FeOx), cobalt oxide (CoOx) and copper oxide (CuO), supported on Al2O3/nickel foam, were used as catalysts. It was found that introducing catalysts could improve toluene removal efficiency, promote decomposition of by-product ozone and enhance CO2 selectivity. In addition, NOx was suppressed with the decrease of specific energy density (SED) and the increase of humidity, gas flow rate and toluene concentration, or catalyst introduction. Among the four kinds of catalysts, the CuO catalyst showed the best performance in NOx suppression. The MnOx catalyst exhibited the lowest concentration of O3 and highest CO2 selectivity but the highest concentration of NOx. A possible pathway for NOx production in DBD was discussed. The contributions of oxygen active species and hydroxyl radicals are dominant in NOx suppression.