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Battery degradation results from multiple factors that usually correlate with each other. Electrochemical corrosion of the current collector is one of the main reasons for battery failure, leading to poor internal electrical contact and the dissolution of harmful ions into electrolytes. This phenomenon is especially evident in lithium bistrifluoromethanesulfonimidate (LiTFSI)-based electrolytes, although they have many advantages over conventional lithium hexafluorophosphate (LiPF6)-based electrolytes, such as low viscosity, good thermal stability, and stable to water. Recently, highly concentrated electrolytes are found hopeful of inhibiting aluminum's corrosion and boosting new electrolyte development. Here we discuss the solvation structures of liquid electrolytes and decouple the degradation mechanisms of using LiTFSI-based electrolytes in Li(Ni0.8Co0.1Mn0.1)O2/Li metal batteries. The results suggest although concentrated electrolytes inhibit the Al corrosion, the growth of lithium dendrites and the protection of the cathode-electrolyte interphase are not significantly improved. This paper provides a paradigm to evaluate the performance of electrolytes comprehensively.

The practical deployment of advanced Li-S batteries is severely constrained by the uncontrollable lithium polysulfide conversion under realistic conditions. Although a plethora of advanced sulfur hosts and electrocatalysts have been examined, the fundamental mechanisms are still elusive and predictive design approaches have not yet been established. Here, we examined a series of well-defined Fe-N-C sulfur hosts with systematically varied and strongly coupled Fe3C and Fe electrocatalysts, prepared by one-step pyrolysis of a novel Fex[Fe(CN)6]y/polypyrrole composite at different temperatures. We revealed the key roles of Fe3C and metallic Fe on modulating polysulfide conversion, in that the polar Fe3C strongly adsorbs polysulfide whereas the Fe particles catalyze fast polysulfide conversion. We then highlight the superior performance of the rational host with strongly coupled Fe3C and Fe on mesoporous Fe-N-C host on promoting nearly complete polysulfide conversion, especially for the challenging short-chain Li2S4 conversion to Li2S. The electrodeposited Li2S on this host was extremely reactive and can be readily charged back to S with minimal activation overpotential. Overall, Li-S batteries equipped with the novel sulfur host delivered a high specific capacity of 1350 mAh g-1 at 0.1C with a capacity retention of 96% after 200 cycles. This work provides new insights on the functional mechanism of advanced sulfur hosts, which could eventually translate into new design principles for practical Li-S batteries.

Summary Grain-boundary engineering is pivotal to fully utilize the mechanical, electrical, and thermal-transport properties of various materials. However, current methods in metallurgy rely almost exclusively on top-down approaches, making precise grain-boundary engineering, especially at nanoscale, difficult to achieve. Herein, we report a method to produce tailored grain-boundary conditions with nanoscale precision from colloidal metal nanocrystals through surface treatment followed by a pressure-sintering process. The resulting bulk grain-boundary materials (which we call “nanocrystal coins”) possess a metal-like appearance and conductivity while inheriting the original domain features of the nanocrystal building blocks. Nanoindentation measurements confirmed the superior mechanical hardness of the obtained materials. Further, we use this method to fabricate, for the first time, a single-component bulk metallic glass from amorphous palladium nanoparticles. Our discovery may spur the development of new materials whose functionality crucially depends on the domain configuration at nanoscale, such as superhard materials, thermoelectric generators, and functional electrodes.

Sodium-ion batteries are promising candidates for energy storage application, but the absence of high-capacity and low-cost anode materials significantly limits their practical specific energy and ...

Alloy-based materials are promising anodes for rechargeable batteries because of their higher theoretical capacities in comparison to graphite. Unfortunately, the huge volume changes during cycling...

One of the grand challenges that impedes practical applications of nanomaterials is the lack of robust manufacturing methods that are scalable, cheap, and environmentally friendly. Herein, we address this challenge by developing a microfluidic approach that produces surfactant-free Pd nanocrystals (NCs) uniformly loaded on N-doped porous carbon in a one-batch process. The deep eutectic solvent (DES) prepared from choline chloride and ethylene glycol was employed as a novel synthesis solvent, and its extended hydrogen networks and abundant ionic species effectively stabilize Pd facets and confine nanocrystal sizes without using surfactants. The microreactors provide faster heat exchange and more uniform mass transport, which in combination with DES produced Pd NCs with better-defined shape and predominately exposed Pd (100) facet. Furthermore, we describe that the N-doped functional groups in porous carbon direct dense and uniform heterogeneous growth of Pd NCs in a one-batch process, thereby eliminating a separate catalyst deposition step that is often involved in conventional synthesis. The Pd NCs in the one-batch-produced Pd/C catalysts exhibited a size distribution of ∼13 ± 3.5 nm and a high ESCA of 46.0 m

In this paper, we investigate the similarity property of the sample projection depth contours. It turns out that parts of the projection depth contours are of the same shape but with different size...

Concerns about the toxicity of lead-based perovskites have aroused great interest for the development of alternative lead-free perovskite-type materials. Recently, theoretical calculations predict that Pb2+ cations can be substituted by a combination of Cu2+ and Sb3+ cations to form a vacancy-ordered layered double perovskite structure with superior optoelectronic properties. However, accessibilities to this class of perovskite-type materials remain inadequate, hindering their practical implementations in various applications. Here, we report the first colloidal synthesis of Cs4CuSb2Cl12 perovskite-type nanocrystals (NCs). The resulting NCs exhibit a layered double perovskite structure with ordered vacancies and a direct band gap of 1.79 eV. A composition-structure-property relationship has been established by investigating a series of Cs4CuxAg2-2xSb2Cl12 perovskite-type NCs (0 ≤ x ≤ 1). The composition induced crystal structure transformation, and thus, the electronic band gap evolution has been explored by experimental observations and further confirmed by theoretical calculations. Taking advantage of both the unique electronic structure and solution processability, we demonstrate that the Cs4CuSb2Cl12 NCs can be solution-processed as high-speed photodetectors with ultrafast photoresponse and narrow bandwidth. We anticipate that our study will prompt future research to design and fabricate novel and high-performance lead-free perovskite-type NCs for a range of applications.

The decoration of two-dimensional (2D) substrates with nanoparticles (NPs) serve as heterostructures for various catalysis applications. Deep understanding of catalyst degradation mechanisms during...

Superelasticity associated with the martensitic transformation has found a broad range of engineering applications1,2. However, the intrinsic hysteresis3 and temperature sensitivity4 of the first-order phase transformation significantly hinder the usage of smart metallic components in many critical areas. Here, we report a large superelasticity up to 15.2% strain in [001]-oriented NiCoFeGa single crystals, exhibiting non-hysteretic mechanical responses, a small temperature dependence and high-energy-storage capability and cyclic stability over a wide temperature and composition range. In situ synchrotron X-ray diffraction measurements show that the superelasticity is correlated with a stress-induced continuous variation of lattice parameter accompanied by structural fluctuation. Neutron diffraction and electron microscopy observations reveal an unprecedented microstructure consisting of atomic-level entanglement of ordered and disordered crystal structures, which can be manipulated to tune the superelasticity. The discovery of the large elasticity related to the entangled structure paves the way for exploiting elastic strain engineering and development of related functional materials. NiCoFeGa single crystals exhibit large non-hysteretic superelasticity over broad temperature and composition ranges. It is attributed to the continuous phase transition with applied stress, which is related to the fluctuation of entangled ordered and disordered crystal structures.

The low-cost hydrogen production from water electrolysis is crucial to the deployment of sustainable hydrogen economy but is currently constrained by the lack of active and robust electrocatalysts from earth-abundant materials. We describe here an unconventional heterostructure composed of strongly coupled Ni-deficient LixNiO nanoclusters and polycrystalline Ni nanocrystals and its exceptional activities toward the hydrogen evolution reaction (HER) in aqueous electrolytes. The presence of lattice oxygen species with strong Bronsted basicity is a significant feature in such heterostructure, which spontaneously split water molecules for accelerated Volmer H-OH dissociation in neutral and alkaline HER. In combination with the intimate LixNiO and Ni interfacial junctions that generate localized hotspots for promoted hydride coupling and hydrogen desorption, the catalysts produce hydrogen at a current density of 10 mA cm-2 under overpotentials of only 20, 50, and 36 mV in acidic, neutral, and alkaline electrolytes, respectively, making them among the most active Pt-free catalysts developed thus far. In addition, such heterostructures also exhibited superior activity toward the hydrogen oxidation reaction in alkaline electrolytes.

The research concerns the reduction of graphene oxide (GO) by excess electrons on TiO2 nanocrystallites, eTiO2–, produced with the aid of ionizing radiation in the presence of 2-propanol at acidic ...

Development of high-performance hydrogen oxidation catalysts with ultralow precious metal loading is critical to the development of next-generation anion-exchange membrane fuel cells. Here, a novel Ru-rich Pt–RuO2 heterojunction catalyst was synthesized via a solvothermal process followed by thermal treatment. The Pt–RuO2 catalyst has ultrafine Pt clusters and a heterojunction interface between Pt and RuO2, which facilitates high hydrogen oxidation activity while minimizing adverse adsorption of the phenyl group in the polymer electrolyte. The performance of a membrane electrode assembly employing the Pt–RuO2/C reached a peak power density of 0.77 W cm−2 with an anode Pt loading of 25 μgPt cm−2, achieving a specific power of 31 W mgPt−1 under H2/O2 conditions. The combined analysis of electrode performance and cost indicates that Pt–RuO2/C is one of the most promising catalysts that is approaching the U.S. DOE 2020 performance and cost targets for transportation applications.

To understand the effect of selenium doping on the good cycling performance and rate capability of a Ge0.9Se0.1 electrode, the dynamic morphological and phase changes of the Ge0.9Se0.1 electrode were investigated by synchrotron-based operando transmission X-ray microscopy (TXM) imaging, X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The TXM results show that the Ge0.9Se0.1 particle retains its original shape after a large volume change induced by (de)lithiation and undergoes a more sudden morphological and optical density change than pure Ge. The difference between Ge0.9Se0.1 and Ge is attributed to a super-ionically conductive Li–Se–Ge network formed inside Ge0.9Se0.1 particles, which contributes to fast Li-ion pathways into the particle and nano-structuring of Ge as well as buffering the volume change of Ge. The XRD and XAS results confirm the formation of a Li–Se–Ge network and reveal that the Li–Se–Ge phase forms during the early stages of lithiation and is an inactive phase. The Li–Se–Ge network also can suppress the formation of the crystalline Li15Ge4 phase. These in situ and operando results reveal the effect of the in situ formed, super-ionically conductive, and inactive network on the cycling performance of Li-ion batteries and shed light on the design of high capacity electrode materials.

Nanoscale oxide-based negative electrodes are of great interest for lithium ion batteries due to their high energy density, power density and enhanced safety. In this work, we conducted a case study on mesoporous TiO2 nanoparticle negative electrodes with uniform size and varying crystallinity in order to investigate the trend in the electrochemical properties of oxide-based nanoscale negative electrodes with varying crystallinity. Mesoporous solid spherical TiO2 nanoparticles with a uniform particle size and varying crystallinity, i.e., amorphous TiO2 (A-TiO2), partially crystalline TiO2 (PC-TiO2) and fully crystalline TiO2 (FC-TiO2) nanoparticles were studied. At low current rate (quasi steady-state), the specific capacity of the samples drops with the decrease of crystallinity. Ex situ synchrotron pair distribution function analysis reveals that the 1D zigzag Li ion diffusion pathway becomes expanded with the increase of crystallinity, which promotes ion mobility and charge storage. At high current rates (away from equilibrium states), however, the A-TiO2 sample demonstrates slightly larger capacity than the FC-TiO2 sample, both of which show larger capacities than that of the PC-TiO2 sample. Both A-TiO2 and FC-TiO2 samples exhibit higher capacitive contribution to the charge storage and larger Li+ diffusivity than those of the PC-TiO2 sample, which explains their better rate capability. Moreover, the larger Li+ diffusivity of the A-TiO2 sample leads to the slightly larger specific capacity than the FC-TiO2 sample at the highest current rate.

Ceramic aerogels exhibit remarkable thermal insulation for energy efficient building applications, while it is indispensable to understand their nanoporous structure evolution to control their thermal regulation performance. In this study, we design and synthesize a lightweight porous silica aerogel monolithic material, and demonstrate its thermal insulation performance regulated by the morphology of porous nanostructures controlled by surfactant induced self-assembly. The micelle networks and in situ gas bubble formation guide the formation of uniform pores in the as-synthesized monolith, which shows superior thermal and acoustic insulation and robust mechanical stability with a thermal conductivity of 0.032 W m−1 K−1, a soundproof performance improvement by 17% at a frequency of 800 Hz, and a 1.3 MPa compressive strength with a Young's modulus of 15 MPa. These findings provide a new route to manufacture low-cost aerogel monolithic insulation materials for energy efficient building applications.

Self-assembled peptide micelles and fibers demonstrate unique control over the photophysical properties of the bound, light-activated chromophore, zinc protoporphyrin IX, (PPIX)Zn. Micelles encapsulate either a mixture of uncoordinated and coordinated (PPIX)Zn or all coordinated depending on the ratio of peptide/porphyrin. As the ratio increases toward a 1:1 micelle/porphyrin ratio, providing the chromophore with a discrete coordination environment reminiscent of unstructured proteins, the micelles favor triplet formation. Fibers, however, promote a linear array of porphyrin molecules that dictates exciton hopping and excimer formation at ratios as high as 60:1, peptide/porphyrin. However, even in fibers, the formation of the triplet species increases with increasing peptide/porphyrin ratio due to increased spatial separation between neighboring chromophores facilitating intersystem crossing. Full characterization of the micelles structures and comparison to the fibers lead to the comparison with natural systems and the ability to control the excited populations that have utility in photocatalytic processes. In addition, the incorporation of a second chromophore, heme, yields an electron transfer pathway in both micelles and fibers that highlights the utility of the peptide assemblies when engineering multichromophore arrays as inspired by natural, photosynthetic proteins.

A novel and advanced approach of growing zinc oxide nanowires (ZnO NWs) directly on single-walled carbon nanotubes (SWCNTs) and graphene (Gr) surfaces has been demonstrated through the successful formation of 1D–1D and 1D–2D heterostructure interfaces. The direct two-step chemical vapor deposition (CVD) method was utilized to ensure high-quality materials’ synthesis and scalable production of different architectures. Iron-based universal compound molecular ink was used as a catalyst in both processes (a) to form a monolayer of horizontally defined networks of SWCNTs interfaced with vertically oriented ZnO NWs and (b) to grow densely packed ZnO NWs directly on a graphene surface. We show here that our universal compound molecular ink is efficient and selective in the direct synthesis of ZnO NWs/CNTs and ZnO NWs/Gr heterostructures. Heterostructures were also selectively patterned through different fabrication techniques and grown in predefined locations, demonstrating an ability to control materials’ placement and morphology. Several characterization tools were employed to interrogate the prepared heterostructures. ZnO NWs were shown to grow uniformly over the network of SWCNTs, and much denser packed vertically oriented ZnO NWs were produced on graphene thin films. Such heterostructures can be used widely in many potential applications, such as photocatalysts, supercapacitors, solar cells, piezoelectric or thermal actuators, as well as chemical or biological sensors.

The recent discovery of ferromagnetism in two-dimensional van der Waals crystals has provoked a surge of interest in the exploration of fundamental spin interaction in reduced dimensions. However, existing material candidates have several limitations, notably lacking intrinsic room-temperature ferromagnetic order and air stability. Here, motivated by the anomalously high Curie temperature observed in bulk diluted magnetic oxides, we demonstrate room-temperature ferromagnetism in Co-doped graphene-like Zinc Oxide, a chemically stable layered material in air, down to single atom thickness. Through the magneto-optic Kerr effect, superconducting quantum interference device and X-ray magnetic circular dichroism measurements, we observe clear evidences of spontaneous magnetization in such exotic material systems at room temperature and above. Transmission electron microscopy and atomic force microscopy results explicitly exclude the existence of metallic Co or cobalt oxides clusters. X-ray characterizations reveal that the substitutional Co atoms form Co2+ states in the graphitic lattice of ZnO. By varying the Co doping level, we observe transitions between paramagnetic, ferromagnetic and less ordered phases due to the interplay between impurity-band-exchange and super-exchange interactions. Our discovery opens another path to 2D ferromagnetism at room temperature with the advantage of exceptional tunability and robustness., Van der Waals magnetic materials (vdWs) have allowed for the exploration of the two dimensional limit of magnetism, however, most vdWs are only magnetic at low temperature. Herein, the authors overcome this limitation, observing room temperature magnetic ordering in Cobalt doped graphene-like Zinc-Oxide.

Atomic-level understanding of the active sites and transformation mechanisms under realistic working conditions is a prerequisite for rational design of high-performance photocatalysts. Here, by using correlated scanning fluorescence X-ray microscopy and environmental transmission electron microscopy at atmospheric pressure, in operando, we directly observe that the (110) facet of a single Cu2O photocatalyst particle is photocatalytically active for CO2 reduction to methanol while the (100) facet is inert. The oxidation state of the active sites changes from Cu(i) towards Cu(ii) due to CO2 and H2O co-adsorption and changes back to Cu(i) after CO2 conversion under visible light illumination. The Cu2O photocatalyst oxidizes water as it reduces CO2. Concomitantly, the crystal lattice expands due to CO2 adsorption then reverts after CO2 conversion. The internal quantum yield for unassisted wireless photocatalytic reduction of CO2 to methanol using Cu2O crystals is ~72%. Photocatalytic reduction of CO2 to methanol offers a promising route to storage of solar energy in the form of chemical fuels. Here, Wu et al. use in operando microscopy to identify the active facets for CO2 reduction on Cu2O and exploit this to obtain high conversion efficiency and selectivity to methanol.

In finance and economics, predictive regression models are widely used. It is known that the limit distributions of their least squares estimators are nonstandard, and depend on the properties of t...

The engineering of biological pathways with man-made materials provides inspiring blueprints for sustainable fuel production. Here, we leverage a top-down cellular engineering strategy to develop a...

Despite their relatively high capacity, layered lithium transition metal oxides suffer from crystal and interfacial structural instability under aggressive electrochemical and thermal driving forces, leading to rapid performance degradation and severe safety concerns. Here we report a transformative approach using an oxidative chemical vapour deposition technique to build a protective conductive polymer (poly(3,4-ethylenedioxythiophene)) skin on layered oxide cathode materials. The ultraconformal poly(3,4-ethylenedioxythiophene) skin facilitates the transport of lithium ions and electrons, significantly suppresses the undesired layered to spinel/rock-salt phase transformation and the associated oxygen loss, mitigates intergranular and intragranular mechanical cracking, and effectively stabilizes the cathode–electrolyte interface. This approach remarkably enhances the capacity and thermal stability under high-voltage operation. Building a protective skin at both secondary and primary particle levels of layered oxides offers a promising design strategy for Ni-rich cathodes towards high-energy, long-life and safe lithium-ion batteries. Intensive research efforts are underway to enable applications of layered lithium transition metal oxides in batteries. Here the authors report an oxidative chemical vapour deposition technique to conformally coat both the primary and the secondary particles of these oxides to unleash potential applications.

In this study, Li(Ni1/3Mn1/3Co1/3)O2 (NMC333) and Li(Ni0.5Mn0.3Co0.2)O2 (NMC532) have been subjected to a phosphoric acid (H3PO4) solution treatment to form a thin Li3PO4 coating on their surfaces. The Li3PO4 coating formed is found to be very potent in enhancing the specific capacity of the first discharge as well as the rate capability and capacity retention in the subsequent charge/discharge cycles for both NMC333 and NMC532. The specific capacity of the first discharge for NMC532 has been increased drastically from ∼160 mA h g−1 for pristine NMC532 to ∼250 mA h g−1 for Li3PO4-coated counterpart at 0.1C and such a large capacity enhancement is retained throughout the subsequent cycles at 1C. The final specific capacity of Li3PO4-coated NMC532 is 187 mA h g−1 after 100 cycles at 1C, whereas the corresponding value of pristine NMC532 is only 50 mA h g−1. The rate capability has also been improved significantly with Li3PO4-coated NMC532 exhibiting ∼150 mA h g−1 capacity at 6C while pristine NMC532 showing zero capacity. Similar improvements have also been achieved with NMC333. These results demonstrate that the H3PO4 treatment is a facile and general method to improve the electrochemical properties of NMCs with different compositions and can be utilized for practical applications.

Self-assembly of nanocrystals is a promising route for creating macroscale materials that derive function from the properties of their nanoscale building blocks. While much progress has been made assembling nanocrystals into different superlattices, controlling the relative orientations of nanocrystals in those lattices remains a challenge. Here, we combine experiments with computer simulations to study the self-assembly of patchy heterostructural nanocrystals (HNCs), consisting of near-spherical quantum dots decorated with regular arrangements of small gold satellites, into close-packed superlattices with pronounced orientational alignment of HNCs. Our simulations indicate that the orientational alignment is caused by van der Waals interactions between gold patches and is sensitive to the interparticle distance in the superlattice. We demonstrate experimentally that the degree and type of orientational alignment can be controlled by changing ligand populations on HNCs. This study provides guidance for the design and fabrication of nanocrystal superlattices with enhanced structural control.

A carbon coated commercial lithium titanium oxide (Li4Ti5O12; LTO) was acoustically mixed with nano-sized AlF3 and heat treated to form a simultaneous coating layer of carbon and AlF3 on LTO particles. The surface modified LTO samples were characterized by a variety of means such as X-ray diffraction, Fourier transform infrared spectrometer, high-resolution transmission electron microscope, and inductively coupled plasma mass spectrometry. The results indicate that both carbon and AlF3 layers exist on the surface of LTO particles and that the distribution of the carbon and AlF3 differs depending on post heat treatment temperature. The carbon and AlF3 coating layers formed by optimal post heat treatment at 350 °C significantly improves electrochemical performance, which increases charge capacity by 30% over the pristine LTO after 50 cycles at a high current density of 5C. Thus, LTO with a simultaneous coating layer of carbon and AlF3 formed by acoustic mixing and post heat treatment shows a potential to further improve commercially-optimized carbon-coated LTO by alleviating its inherently low conductivity. This is an effective way to stabilize the interface between LTO particles and electrolyte, and is a practical approach to promote the wide usage of LTO, one of the most potent anode materials.

Tin (Sn) is a potential anode material for highenergy density Li-ion batteries because of its high capacity, safety, abundance and low cost. However, Sn suffers from large volume change during cycling, leading to fast degradation of the electrode. For the first time, the microstructural evolution of micrometer-sized single Sn particle was monitored by focused-ion beam (FIB) polishing and scanning electron microscopy (SEM) imaging during electrochemical cycling by in situ FIB-SEM. Our results show the formation and evolution of cracks during lithiation, evolution of porous structure during delithiation and volume expansion/contraction during cycling. The electrochemical performance and the microstructural evolution of the Sn microparticle during cycling are directly correlated, which provides insights for understanding Sn-based electrode materials.

Nanophase zinc oxide (ZnO) has been widely studied as an important multifunctional material in many applications. Atomic layer deposition (ALD) is a unique thin-film synthesis technique, featuring its extreme uniformity, unrivaled conformal coverage, low deposition temperature, and precise controllability. Using diethylzinc (DEZ) and water as precursors, ALD has been reported previously for growing nanophase ZnO thin films. However, the growth characteristics and the resultant ZnO crystallinity have not been well characterized and understood. To this end, we revisited the ALD process of ZnO using DEZ and water. Through employing a suite of advanced characterization techniques, we systematically addressed the growth characteristics, morphological changes, and the crystallinity evolution of ZnO along with growth temperature in the range of 30–250 °C. The growth characteristics of the ALD ZnO films were investigated using in situ quartz crystal microbalance (QCM), scanning electron microscopy, atomic force microscopy, and synchrotron-based X-ray reflectivity. The crystallinity of the ALD ZnO films was determined using synchrotron-based X-ray diffraction and high-resolution transmission electron microscopy. In addition, through further analyzing QCM data, we proposed the adsorption-limited surface reaction for ALD ZnO growth with the temperature-dependent number of –OH surface group reacting with one DEZ molecule. Thus, this study contributes to offer new and deep insights on the fundamental ALD process of ZnO.

Magnetic nanoshells with tailored surface chemistry can enhance bacterial detection and separation technologies. This work demonstrated a simple technique to detect, capture, and aggregate bacteria with the aid of end-functionalized polyclonal antibody gold-coated magnetic nanoshells (pAb-Lis-AuMNs) as surface-enhanced Raman spectroscopy (SERS) probes. Listeria monocytogenes were used as the pathogenic bacteria and the pAb-Lis-AuMNs, 300 nm diameter, were used as probes allowing facile magnetic separation and aggregation. An optimized covalent bioconjugation procedure between the magnetic nanoshells and the polyclonal antibody was performed at pH six via a carbodiimide crosslinking reaction. Spectroscopic and morphological characterization techniques confirmed the fabrication of stable pAb-Lis-AuMNs. The resulting pAb-Lis-AuMNs acted as a SERS probe for L. monocytogenes based on the targeted capture via surface binding interactions and magnetically induced aggregation. Label-free SERS measurements were recorded for the minimum detectable amount of L. monocytogenes based on the SERS intensity at the 1388 cm−1 Raman shift. L. monocytogenes concentrations exhibited detection limits in the range of 104–107 CFU ml−1, before and after aggregation. By fitting these concentrations, the limit of detection of this method was ∼103 CFU ml−1. Using a low-intensity magnetic field of 35 G, pAb-Lis-AuMNs aggregated L. monocytogenes as demonstrated with microscopy techniques, including SEM and optical microscopy. Overall, this work presents a label-free SERS probe method comprised of a surface-modified polyclonal antibody sub-micron magnetic nanoshell structures with high sensitivity and magnetic induced separation that could lead to the fabrication of multiple single-step sensors.

The dynamic information of lithium-ion battery active materials obtained from coin cell-based in-situ characterizations might not represent the properties of the active material itself because many other factors in the cell could have impacts on the cell performance. To address this problem, a single particle cell was developed to perform the in-situ characterization without the interference of inactive materials in the battery electrode as well as the X-ray-induced damage. In this study, the dynamic morphological and phase changes of selenium-doped germanium (Ge0.9 Se0.1 ) at the single particle level were investigated via synchrotron-based in-situ transmission X-ray microscopy. The results demonstrate the good reversibility of Ge0.9 Se0.1 at high cycling rate that helps understand its good cycling performance and rate capability. This in-situ and operando technique based on a single particle battery cell provides an approach to understanding the dynamic electrochemical processes of battery materials during charging and discharging at the particle level.

Bioactive core&ndash, shell nanoparticles (CSNPs) offer the unique ability for protein/enzyme functionality in non-native environments. For many decades, researchers have sought to develop synthetic materials which mimic the efficiency and catalytic power of bioactive macromolecules such as enzymes and proteins. This research studies a self-assembly method in which functionalized, polymer-core/protein-shell nanoparticles are prepared in mild conditions. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques were utilized to analyze the size and distribution of the CSNPs. The methods outlined in this research demonstrate a mild, green chemistry synthesis route for CSNPs which are highly tunable and allow for enzyme/protein functionality in non-native conditions.

Solid state electrolytes (SSEs) offer great potential to enable high-performance and safe lithium (Li) batteries. However, the scale-up synthesis and processing of SSEs is a major challenge. In this work, three-dimensional networks of lithium lanthanum titanite (LLTO) nanofibers are produced through a scale-up technique based on solution blowing. Compared with the conventional electrospinning method, the solution blowing technique enables high-speed fabrication of SSEs (e.g., 15 times faster) with superior productivity and quality. Additionally, the room-temperature ionic conductivity of composite polymer electrolytes (CPEs) formed from solution-blown LLTO fibers is 70% higher than the ones formed from electrospun fibers (1.9 × 10 -4 vs 1.1 × 10-4 S cm-1 for 10 wt % LLTO fibers). Furthermore, the cyclability of the CPEs made from solution-blown fibers in the symmetric Li cell is more than 2.5 times that of the CPEs made from electrospun fibers. These comparisons show that solution-blown ion-conductive fibers hold great promise for applications in Li metal batteries.

Noncollinear antiferromagnets can have additional spin Hall effects due to the net chirality of their magnetic spin structure, which provides for more complex spin-transport phenomena compared to ordinary nonmagnetic materials. Here we investigated how ferromagnetic resonance of permalloy (${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}$) is modulated by spin Hall effects in adjacent epitaxial ${\mathrm{IrMn}}_{3}$ films. We observe a large dc modulation of the ferromagnetic resonance linewidth for currents applied along the [001] ${\mathrm{IrMn}}_{3}$ direction. This very strong angular dependence of spin-orbit torques from dc currents through the bilayers can be explained by the magnetic spin Hall effect where ${\mathrm{IrMn}}_{3}$ provides novel pathways for modulating magnetization dynamics electrically.

Lithium titanium oxide (Li4Ti5O12, LTO), a ‘zero-strain’ anode material for lithium-ion batteries, exhibits excellent cycling performance. However, its poor conductivity highly limits its applications. Here, the structural stability and conductivity of LTO were studied using in situ high-pressure measurements and first-principles calculations. LTO underwent a pressure-induced amorphization (PIA) at 26.9 GPa. The impedance spectroscopy revealed that the conductivity of LTO improved significantly after amorphization and that the conductivity of decompressed amorphous LTO increased by an order of magnitude compared with its starting phase. Furthermore, our calculations demonstrated that the different compressibility of the LiO6 and TiO6 octahedra in the structure was crucial for the PIA. The amorphous phase promotes Li+ diffusion and enhances its ionic conductivity by providing defects for ion migration. Our results not only provide an insight into the pressure depended structural properties of a spinel-like material, but also facilitate exploration of the interplay between PIA and conductivity.

The O3-type layered Na(NixFeyMnz)O2 (0 < x, y, z < 1) cathode materials have attracted great interest in sodium ion batteries due to the abundance and cost of raw materials and their high specific ...

The key to enabling long-term cycling stability of high-voltage lithium (Li) metal batteries is the development of functional electrolytes that are stable against both Li anodes and high-voltage (above 4 V versus Li/Li+) cathodes. Due to their limited oxidative stability ( 90% over 300 cycles and ~80% over 500 cycles with a charge cut-off voltage of 4.3 V. This study offers a promising approach to enable ether-based electrolytes for high-voltage Li metal battery applications. Ether-based electrolytes offer many advantages compared to other electrolyte systems, but they are not stable in Li metal batteries when operating at high voltages. Here, the authors develop a concentrated ether electrolyte that enables long-term cycling stability of high-voltage Li metal batteries.

Films containing mixtures of zero- or two-dimensional nanostructures (quantum dots or nanoplatelets) were prepared in order to investigate the impacts of dimensionality on electronic interactions. Electron transfer from CsPbBr3 to CdSe was observed in all of the mixtures, regardless of particle dimensionality, and characterized via both static and transient absorption and photoluminescence spectroscopies. We find that mixtures containing nanoplatelets as the electron acceptor (CdSe) undergo charge transfer more rapidly than those containing quantum dots. We believe the faster charge transfer observed with nanoplatelets may arise from the extended spatial area of the CdSe nanoplatelets and/or the continuous density of acceptor states that are present in nanoplatelets. These results bolster the use of one- or two-dimensional nanomaterials in the place of zero-dimensional quantum dots in the design of related optoelectronic devices such as solar cells, light-emitting diodes, and photocatalysts and further of...

Noble metal-free highly efficient cocatalysts are very important for cost efficient hydrogen fuel production. While most studies concentrate on single cocatalyst photocatalytic systems. Here, we report on the synthesis of Mn0.5Cd0.5S photocatalyst hetero-architecture with synergistic spatially separated dual cocatalysts Cu2−xS and MoS2 for highly efficient photocatalytic H2 production. Through tactfully utilizing Cu2−xS/Mn0.5Cd0.5S nanoscale p-n junction to promote efficient transfer of photo-generated holes to Cu2−xS and MoS2 can be located exactly on the different positions where the photo-generated electrons must go through by photo-reduction of (NH4)2MoS4. Cu2−xS can be an oxidation active site to assemble photo-generated holes and MoS2 can capture and transport the photon-generated electrons. Therefore the photo-induced carriers can be efficiently separated and transferred to take part in photocatalytic reactions. The prepared Cu2−xS (0.015)/Mn0.5Cd0.5S/MoS2 (3 wt%) photocatalyst shows the highest H2 production rate of 687.62 μmol/h, which exceeds the rate of Mn0.5Cd0.5S and Mn0.5Cd0.5S loaded with Cu2−xS or MoS2 alone by 22, 1.7 and 3.48 times, respectively. This work provides a new thought to design efficient spatially separated and synergistic dual cocatalysts modified photocatalysts for H2 production.

A general strategy has been developed here to co-assemble polyoxometalates (POMs) and polymers into core–shell hybrid nanoparticles via hydrogen bonding interaction. Due to the hydrogen bonds between the pyridine groups of poly(4-vinyl pyridine) (P4VP) and the hydrogen bonding donor groups on the POM surface, P4VP is stabilized by the POMs and dispersed as discrete hybrid core–shell nanoparticles in aqueous solution. For these thermodynamically stable nanoparticles, the P4VP cores are covered with hexagonal close-packed POMs. The size of the core–shell particles is controlled by the electrostatic repulsive interaction among the POMs. The introduction of extra salts screens the repulsive force among the POMs, thus increasing the size of the core–shell structures.

Highly dispersed Pt–Co bimetallic catalysts were deposited on multi-walled carbon nanotubes (MWCNTs) by atomic layer deposition. High-resolution TEM and TPR analyses verified the formation of Pt–Co bimetallic particles. Catalysts were applied for the hydrogenolysis of 5-hydroxymethyfurfural (HMF) to 2,5-dimethyfuran (DMF). A high yield of DMF (>90%) was achieved in the hydrogenolysis of HMF over the optimized Pt–Co/MWCNTs catalyst after 8 h of reaction time under 10 bar H2 at 160 °C. Through a series of experiments and comparison, the synergistic effect among Pt, Co, and MWCNTs was investigated. The results revealed that the synergistic effect between Pt–Co and MWCNTs played an important role in the improvement of selectivity to DMF for Pt–Co/MWCNTs bimetallic catalysts. In addition, steric hindrance appeared when Co loading in Pt–Co/MWCNTs was high and it affected the activity of the Pt–Co bimetallic catalysts. However, moderate activity can inhibit the production of byproducts and thereby improve the yield of DMF.

Utilizing silicon as an anode material for Li-ion batteries has been the subject of many studies. However, due to the huge volume change of silicon during lithiation, the electrochemical performance of silicon is poor. Here, we have investigated a novel yet simple approach to synthesize nanostructured silicon/graphite composites with a carbon coating and engineered voids. High-energy ball mill is employed to convert micrometer-sized silicon and graphite to nanostructured silicon/graphite composite building blocks, while a thin carbon coating is applied to encapsulate these composite agglomerates, followed by partial etching of silicon to create engineered voids inside the composite agglomerates. The batteries made with this tailored nanostructure exhibit improved electrochemical performance over the counterparts made with silicon nanoparticles and exhibited a specific capacity of ∼1800 mA h g−1 discharge capacity at the first cycle, 580 mA h g−1 after 40 cycles, and 350 mA h g−1 after 300 cycles. This study has established a novel method scalable at industry environment and capable of producing low cost Si anodes and clearly shown that the cycle stability of the tailored nanostructure improves with increasing engineered voids in the range we have investigated.

Recently, additive manufacturing (AM) has brought new opportunities to the manufacturing of lithium-ion batteries (LIBs). In this study, aerosol jet printing, as a branch of AM technologies was demonstrated to fabricate lithium-ion batteries for the first time. Printable inks of two pairs of active materials for cathode and anode were developed. The effect of ink composition on the printing characteristics was studied. The developed inks were printed into Li-ion battery electrodes with specific capacities comparable to conventional slurry cast electrodes. Next, to demonstrate fully-printed electrodes, gold and copper inks were printed on top of polymer substrates and thermal/flash sintered as the current collectors for cathode and anode.

In this study, silicon nanoparticles are oxidized in a controlled manner to obtain different thicknesses of SiO2 layers. Their stability in aqueous slurries as well as the effect of oxide layer thickness on the electrochemical performance of the silicon anodes is evaluated. Our results show that slightly increasing the oxide layer of silicon nanoparticles significantly improves the stability of the nanoparticles in aqueous slurries and does not compromise the initial electrochemical performance of the electrodes. A careful comparison of the rate and cycle performance between 400 °C treated Si nanoparticles and pristine Si nanoparticles shows that by treating the silicon nanoparticles in air for slightly increasing the oxide layer, improvement in both rate and cycle performance can be achieved.

A pure phase of VO2(B) nanorods have been synthesized through an energy-efficient microwave hydrothermal reaction and used as cathode materials of lithium ion batteries, which exhibit promising specific capacity (e.g., 130 mA h g−1 even after 100 charge/discharge cycles) and rate capacity (e.g., ~130 mA h g−1 at a high current of 400 mA g−1). The excellent cyclability originates from the structural reversibility of VO2(B) upon lithiation/delithiation that is confirmed by the in situ high-energy synchrotron X-ray diffraction (HEXRD) and in situ x-ray adsorption near-edge spectroscopy (XANES) of the VO2 nanorods in operating battery cells. The real-time results reveal that discharge forces lithium ions to insert firstly into the tunnels with the largest size along b direction followed by the second largest tunnels along c direction, which is completely reversible in the charge process.

Dissolution is critical to nanomaterial stability, especially for partially dealloyed nanoparticle catalysts. Unfortunately, highly active catalysts are often not stable in their reactive environments, preventing widespread application. Thus, focusing on the structure–stability relationship at the nanoscale is crucial and will likely play an important role in meeting grand challenges. Recent advances in imaging capability have come from electron, X-ray, and other techniques but tend to be limited to specific sample environments and/or two-dimensional images. Here, we report investigations into the defect-stability relationship of silver nanoparticles to voltage-induced electrochemical dissolution imaged in situ in three-dimensional detail by Bragg coherent diffractive imaging. We first determine the average dissolution kinetics by stationary probe rotating disk electrode in combination with inductively coupled plasma mass spectrometry, which allows in situ measurement of Ag+ ion formation. We then observe...

Sodium-ion batteries (SIBs) have been considered as one of the promising power source candidates for the stationary storage industries owing to the much lower cost of sodium than lithium. It is well-known that the electrode materials largely determine the energy density of the battery systems. However, recent discoveries on the electrode materials showed that most of them present distinct lithium and sodium storage performance, which is not yet well understood. In this work, we performed a comparative understanding on the structural changes of porous cobalt oxide during its electrochemical lithiation and sodiation process by in operando synchrotron small angel X-ray scattering, X-ray diffraction, and X-ray absorption spectroscopy. It was found that compared to the lithiation process, the porous cobalt oxide undergoes less pore structure changes, oxidation state, and local structure changes as well as crystal structure evolution during its sodiation process, which is attributed to the intrinsic low sodiation activity of cobalt oxide as evidenced by ab initio molecular dynamics simulations. Moreover, it was indicated that the sodiation activity of metal sulfides is higher than that of metal oxides, indicating a better candidate for SIBs. Such understanding is crucial for future design and improvement of high-performance electrode materials for SIBs.

Cathode materials are critical to the energy density, power density and safety of sodium-ion batteries (SIBs). Herein, we performed a comprehensive study to elucidate and exemplify the interplay mechanism between phase structures, interfacial microstrain and electrochemical properties of layered-structured NaxNi1/3Co1/3Mn1/3O2 cathode materials for high voltage SIBs. The electrochemical test results showed that NaxNi1/3Co1/3Mn1/3O2 with an intergrowth P2/O3/O1 structure demonstrates better electrochemical performance and better thermal stability than NaxNi1/3Co1/3Mn1/3O2 with P2/O3 binary-phase integration and NaxNi1/3Co1/3Mn1/3O2 where only the P phase is dominant. This result is caused by the distinct interfacial microstrain development during the synthesis and cycling of the P2/O3/O1 phase. In operando high energy X-ray diffraction further revealed that the intergrowth P2/O1/O3 cathode can inhibit the irreversible P2–O2 phase transformation and simultaneously improve the structure stability of the O3 and O1 phases during cycling. We believe that interfacial microstrain can serve as an indispensable bridge to guide future design and synthesis of high performance SIB cathode materials and other high energy battery materials.

We report an amorphous boron nanorod anode material for lithium-ion batteries prepared through smelting non-toxic boron oxide in liquid lithium. Boron in theory can provide capacity as high as 3099 mA h g−1 by alloying with Li to form B4Li5. However, experimental studies of the boron anode have been rarely reported for room temperature lithium-ion batteries. Among the reported studies the electrochemical activity and cycling performance of the bulk crystalline boron anode material are poor at room temperature. In this work, we utilized an amorphous nanostructured one-dimensional (1D) boron material aiming at improving the electrochemical reactivity between boron and lithium ions at room temperature. The amorphous boron nanorod anode exhibited, at room temperature, a reversible capacity of 170 mA h g−1 at a current rate of 10 mA g−1 between 0.01 and 2 V. The anode also demonstrated good rate capability and cycling stability. The lithium storage mechanism was investigated by both sweep voltammetry measurements and galvanostatic intermittent titration techniques (GITTs). The sweep voltammetric analysis suggested that the contributions from lithium ion diffusion into boron and the capacitive process to the overall lithium charge storage are 57% and 43%, respectively. The results from GITT indicated that the discharge capacity at higher potentials (>∼0.2 V vs. Li/Li+) could be ascribed to a capacitive process and at lower potentials (

Peroxidase mimics composed of inorganic nanoparticles are expected to circumvent the inherent difficulties of natural peroxidases, and to provide enhanced performance in important applications such as diagnosis and imaging. Despite the reports of a variety of peroxidase mimics in the past decade, very limited progress has been made on improving their catalytic efficiency. The catalytic efficiencies of most previously reported mimics are only up to one order of magnitude higher than those of natural peroxidases. In this work, we demonstrate a highly efficient peroxidase—polyvinylpyrrolidone (PVP)-capped Pt nanocubes of sub-10 nm in size. These PVP-capped Pt cubes are ≈200-fold more active than the natural counterparts and exhibit a record-high specific catalytic efficiency. In addition to the superior efficiency, the new mimic shows several other promising features, including excellent stabilities, well-controlled uniformity in both size and shape, controllable sizes, and facile and scalable production.