Versatile Neuromorphic Modulation and Biosensing based on N-type Small-molecule Organic Mixed Ionic-Electronic Conductors.

The ion/chemical-based modulation feature of organic mixed ionic-electronic conductors (OMIECs) are critical to advancing next generation bio-integrated neuromorphic hardware. Despite achievements with polymeric OMIECs in organic electrochemical neuronal synapse (OENS). However, small molecule OMIECs based OENS has not yet been realized. Here, for the first time, we demonstrate an effective materials design concept of combining n-type fused all-acceptor small molecule OMIECs with subtle side chain optimization that enables robustly and flexibly modulating versatile synaptic behavior and sensing neurotransmitter in solid or aqueous electrolyte, operating in accumulation modes. By judicious tuning the ending side chains, the linear oligoether and butyl chain derivative gNR-Bu exhibits higher recognition accuracy for a model artificial neural network (ANN) simulation, higher steady conductance states and more outstanding ambient stability, which is superior to the state-of-art n-type OMIECs based OENS. These superior artificial synapse characteristics of gNR-Bu can be attributed to its higher crystallinity with stronger ion bonding capacities. More impressively, we unprecedentedly realized n-type small-molecule OMIECs based OENS as a neuromorphic biosensor enabling to respond synaptic communication signals of dopamine even at sub-µM level in aqueous electrolyte. This work may open a new path of small-molecule ion-electron conductors for next-generation ANN and bioelectronics.

Aldol Condensation for the Construction of Organic Functional Materials.

Aldol condensation is a cost-effective and sustainable synthetic method, offering the advantages of low complexity, substrate universality, and high efficiency. Over the past decade, it has become popular for creating next-generation organic functional materials, particularly rigid-rod conjugated (semi)conductors. This review focuses on conjugated small molecules, oligomers, and polymeric (semi)conductors synthesized through aldol condensation, with emphasis on their remarkable features in advancing n-type organic field-effect transistors (OFETs), organic electrochemical transistors (OECTs), organic photovoltaics (OPVs), and organic thermoelectrics (OTEs) as well as NIR-II photothermal conversion. Coherence character, optical properties, microstructure, and chain conformation are investigated to understand material-property relationships. Future applications and challenges in this area are also discussed.

Depicting Defects in Metallic Glasses by Atomic Vibrational Entropy.

Due to the chaotic structure of amorphous materials, it is challenging to identify defects in metallic glasses. Here we tackle this problem from a thermodynamic point of view using atomic vibrational entropy, which represents the inhomogeneity of atomic contributions to vibrational modes. We find that the atomic vibrational entropy is correlated to the vibrational mean-square displacement and polyhedral volume of atoms, revealing the critical role of vibrational entropy in bridging dynamics, thermodynamics, and structure. On this method, the local vibrational entropy obtained by coarse-graining the atomic vibrational entropy in space can distinguish more effectively between liquid-like and solid-like atoms in metallic glasses and establish the correlation between the local vibrational entropy and the structure of metallic glasses, offering a route to predict the plastic events from local vibrational entropy. The local vibration entropy is a good indicator of thermally activated and stress-driven plastic events, and its predictive ability is better than that of the structural indicators.

A Durable, Flexible, Large-Area, Flame-Retardant, Early Fire Warning Sensor with Built-In Patterned Electrodes.

Fire has been giving rise to enormous loss of life and property worldwide annually. Early fire warning represents an active and effective means to avoid potential fire hazards before huge losses occur. Despite encouraging advances in early fire warning systems, to date there remains an urgent lack of the design of a durable, flexible, and universal early fire warning sensor for large-area practical applications. Herein, facile fabrication of a durable, flexible, large-scale early fire-warning sensor is demonstrated through constructing a hierarchical flame retardant nanocoating, composed of graphene oxide, poly(dimethylaminoethyl methacrylate), and hexagonal boron nitride, on cotton fabric in combination with the parallelly patterned conductive ink as built-in electrodes. As-designed large-scale sensor (>33 cm and extendable) exhibits a short alarming time of <3 s in response to external abnormal high temperature, heat, or fire. In addition to high washability, flexibility, resistance to abrasion and wear, this hierarchical nanocoating can self-extinguish, thus enabling the sensor to continue warning during fire. This work offers an inventive concept to develop a universal and large-scale very early fire-monitoring platform, which opens up new opportunities for their practical applications in effectively reducing fire-related casualties and economic losses.

Emulsion-templated porous polymers: drying condition-dependent properties.

Macroporous materials templated using high internal phase emulsions (HIPEs) are promising for various applications. To date, new strategies to create emulsion-templated porous materials and to tune their properties (especially wetting properties) are still highly required. Here, we report the fabrication of macroporous polymers from oil-in-water HIPEs, bereft of conventional monomers and crosslinking monomers, by simultaneous ring-opening polymerization and interface-catalyzed condensation, without heating or removal of oxygen. The resulting macroporous polymers showed drying condition-dependent wetting properties (e.g., hydrophilicity-oleophilicity from freezing drying, hydrophilicity-oleophobicity from vacuum drying, and amphiphobicity from heat drying), densities (from 0.019 to 0.350 g cc-1), and compressive properties. Hydrophilic-oleophilic and amphiphobic porous polymers turned hydrophilic-oleophobic simply by heating and protonation, respectively. The hydrophilic-oleophobic porous polymers could remove a small amount of water from oil-water mixtures (including surfactant-stabilized water-in-oil emulsions) by selective absorption and could remove water-soluble dyes from oil-water mixtures. Moreover, the transition in wetting properties enabled the removal of water and dyes in a controlled manner. The feature that combines simply preparation, tunable wetting properties and densities, robust compression, high absorption capacity (rate) and controllable absorption makes the porous polymers to be excellent candidates for the removal of water and water-soluble dyes from oil-water mixtures.

High-throughput screening of single metal atom anchored on N-doped boron phosphide for N2 reduction.

Developing eco-friendly and highly-efficient catalysts for the electrochemical nitrogen reduction reaction (NRR) under ambient conditions to replace the energy-intensive and environment-polluting Haber-Bosch process is of great significance, while remaining a long-standing challenge in the field of energy conversion today. Herein, through the first principles high-throughput screening, we systematically investigated the catalytic activity of a series of single metal atom immobilized on N-doped boron phosphide (N3-BP) for N2 reduction, denoted as MN3-BP. In particular, a "four-step" screening strategy, involving the structural stability, N2 chemisorption, low energy cost, as well as good selectivity, was adopted for the stringent screening of the promising MN3-BP candidates for NRR. Our results unveil that among these candidates, MoN3-BP eventually stands out, benefiting from its high selectivity and activity, as well as accompanying a considerably favorable limiting potential of -0.25 V for NRR. More impressively, the NRR activity origin of various candidates was revealed by the descriptor φ and ICOHP. Overall, our work not only accelerates the discovery of SACs for converting N2 into sustainable NH3 but also provides an exciting impetus for the rational design of NRR catalysts with high stability, high activity, and high selectivity.

Durable Superamphiphobic and Photocatalytic Fabrics: Tackling the Loss of Super-Non-Wettability Due to Surface Organic Contamination.

Superamphiphobic surfaces are self-cleaning against various liquids and dirt particles but they are not resistant to trace organic contaminants, the accumulation of which on surface would cause a decline in the liquid repellency. In this work, superamphiphobic and photocatalytic fabrics are developed that allow the elimination of various organic substances from surface by using photocatalytic decomposition. The fabrics have a contact angle of 163, 156, and 158° to water, hexadecane, and sunflower oil, respectively. They are also demonstrated to be able to decompose methylene blue, oleic acid and sodium dodecyl sulfate (SDS) under UV light. The removal of human body grease or laundry detergent from surface to recover the super-non-wettability was demonstrated through the natural sunlight exposure. The slight damage on superamphiphobicity caused by the photocatalytic activity can be cured with simple heat treatment. In addition, the superamphiphobic fabrics show excellent durability against abrasion and repeated washing. The photocatalytic and heat-curing strategy reported here may bring superamphiphobic fabrics one step closer to practical application in various fields.

Study on the correlation between microstructures and corrosion properties of novel ZrTiAlV alloys.

In this work, microstructures and corrosion behaviors of novel ZrTiAl-χV (χ = 0, 1, 3, 5, 7 wt%) alloys have been investigated. Phase composition and microstructures of the specimens are characterized using X-ray diffraction, optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results show that phase composition of the alloys change by α' → α″ → α″ + ßâ€¯â†’â€¯ß as V is added gradually. Meanwhile, the mean size of the α' phase, α″ martensite and ß phase decreases as V content increases. In order to test the corrosion performance of the specimens, potentiodynamic polarization tests in NaCl and HCl solutions and immersion tests in HCl solution are performed. Analysis of potentiodynamic potential curves indicates that corrosion potential increases and corrosion current density decreases with adding V content in the examined alloys. From the results of weight loss tests, it can be observed that the weight loss of the examined alloys decreases along with the increase of V content. In addition, when the content of V is added from 3 to 7 wt%, the metastable corrosion pits are replaced with the stable corrosion pits. The phase composition as well as the grain size can be identified as the main factor affecting the corrosion performance of the alloys.

Superplastic Forging for Sialon-based Nanocomposite at Ultralow Temperature in the Electric Field.

The utralow-temperature superplastic forging for sialon-based nanocomposites is reported for the first time. Sialon-based nanocomposites, with an average grain size smaller than 50 nm and 98.5% relative density, were prepared with nano-sized row powders by the spark plasma sintering (SPS) technique at a record ultralow sintering temperature of 1150 °C. An excellent gear is forged at the ultralow deformation temperature of 1200 °C with nanosized grains without any cracking. The maximum strain rate achieved is over 10-1 s-1, and a compression strain is more than 0.9. The practical application for superplastic forming of nitrogen ceramics is much more difficult than that for oxide ceramics because of the high deformation temperature and low strain rates. The present findings present a bright prospect for the near-net-shape superplastic forming of nitrogen ceramics.

Influence of Co2+ Ions on the Microstructure and Mechanical Properties of Ni-W/Diamond Nano-Composite Coatings.

The Co were incorporated into the Ni-W/diamond nano-composite coatings by introducing CoSO4 in the aforesaid plating bath. The effects of the Co content in the electrodeposit on microstructure and mechanical properties were analyzed. The morphology and the composition of the deposits were investigated by means of SEM and EDS, respectively. The Co content in the coatings increases progressively upon increasing the amount of CoSO4 in the plating bath. The addition of small amount of CoSO4 in the plating bath tends to enhance the hardness and wear performance of the Ni-W/diamond nano-composite coatings. While the amount of CoSO4 beyond 0.2 g/L in the plating bath, the hardness and the wear resistance of the coatings decrease sharply.

Molecular Dynamics Simulation of Structural Signals of Shear-Band Formation in Zr46Cu46Al8 Metallic Glasses.

The evolution from initiation to formation of a shear band in Zr46Cu46Al8 metallic glasses is presented via molecular dynamics simulation. The increase in number and the decrease in average size of clusters with the quasi-nearest atoms being 0 correspond to the shear-band evolution from initiation to formation. When the shear band is completely formed, the distribution of the bond orientational order q6 reaches a minimum. The maximum of the number of the polyhedral loss of Cu-centered <0, 0, 12, 0> and the minimum of the number of the polyhedral loss of Zr-centered <0, 2, 8, 5> correspond to the shear-band formation. These findings provide a strong foundation for characterizing the evolution from initiation to formation of shear bands.

Rational design and synthesis of SiC/TiC@SiOx/TiO2 porous core-shell nanostructure with excellent Li-ion storage performance.

Rational design and synthesis of a new silicon carbide/titanium carbide@silicon oxide/titanium dioxide (SiC/TiC@SiOx/TiO2) porous core-shell nanostructured material could significantly enhance the specific capacity, rate capability, and cycle stability of electrodes. The results demonstrate that the specific capacities are 387, 300, 252, 210, 174 and 151 mA h g-1 at 100, 200, 500, 1000, 1500 and 2000 mA g-1, respectively. The newly designed electrode still exhibits a larger specific capacity of 217 mA h g-1 at 1000 mA g-1 after the 1000th cycle.

Heterostructured d-Ti3 C2 /TiO2/ g-C3 N4 Nanocomposites with Enhanced Visible-Light Photocatalytic Hydrogen Production Activity.

The construction of a 2D-2D heterostructured composite is an efficient method to improve the photocatalytic hydrogen generation capability under visible light. In this work, simple heat treatment of a mixture of g-C3 N4 and delaminated Ti3 C2 was used to prepare a series of d-Ti3 C2 /TiO2 /g-C3 N4 nanocomposites. The d-Ti3 C2 not only acted as the support layer and resource to glue the anatase TiO2 particles and g-C3 N4 layers together but also served as the fast electron transfer channel to improve the photogenerated charge carriers' separation efficiency. By tuning the g-C3 N4 /d-Ti3 C2 mass ratio, heating temperature and soaking time, the d-Ti3 C2 /TiO2 /g-C3 N4 nanocomposite 4-1-350-1 achieved an excellent H2 evolution rate of 1.62 mmol h-1 g-1 driven by a 300 W Xe lamp with a 420 nm cutoff filter. The heterostructured composite photocatalyst was stable even after 3 cycles, representing excellent potential for the practical application in solar energy conversion.

WS2 and C-TiO2 Nanorods Acting as Effective Charge Separators on g-C3 N4 to Boost Visible-Light Activated Hydrogen Production from Seawater.

Semiconductor photocatalysis is regarded as an ideal method for use in solving the energy shortage and environmental issues by converting solar energy to chemical energy. Herein, we have designed a facile synthetic methodology to obtain a ternary co-modified g-C3 N4 composite via WS2 and carbon-doped TiO2 (C-TiO2 ) nanorods with highly efficient photocatalytic activity for hydrogen production from deionized (DI) water and a natural seawater system under visible-light illumination. This composite exhibits enhanced photocatalytic activity compared to the pristine g-C3 N4 , WS2 , C-TiO2 nanorods, and the reference-modified g-C3 N4 composite with individual WS2 or C-TiO2 nanorods. Co-modified g-C3 N4 composite shows a great photostability in both DI water and seawater. Under λ=420 nm monochromatic light illumination, the apparent quantum efficiency of the co-modified g-C3 N4 composite in seawater solution is 13.08 %, which is higher than pure g-C3 N4 (5.06 %). WS2 , TiO2 , and g-C3 N4 constitute a ternary heterojunction boosting the fast separation of photoinduced electron-hole pairs, which plays a crucial role in enhancing photocatalytic activity. Therefore, the WS2 and C-TiO2 nanorod co-modified g-C3 N4 composite with high photocatalytic performance provides a promising candidate for rationally utilizing the seawater resource to produce clean chemical energy.

Facile Electrodeposition of Ni-Cu-P Dendrite Nanotube Films with Enhanced Hydrogen Evolution Reaction Activity and Durability.

Hydrogen can be the potential substitute energy carrier for fuel while electrolysis water with hydrogen evolution reaction (HER) is an efficient way to produce hydrogen. Highly active and robust electrocatalysts composed by earth abundant elements are required. Herein, nickel-copper-phosphorus (Ni-Cu-P) electrocatalysts are designed and synthesized by a facile one-step electrodeposition method. A unique pine-needle-like dendrite nanotube morphology of Ni-Cu-P electrocatalyst can be synthesized when copper content changed and impressive HER activity obtained in alkaline and acidic media. Briefly, the overpotential reaches 120 mV in 1 M KOH and 150 mV in 0.5 M H2SO4 at the current density of 10 mA cm-2, with the corresponding Tafel slope reaching 69 mV dec-1. The results are close to that of commercial Pt/C catalysts (37 mV in 1 M KOH). Furthermore, the density functional theory calculations also demonstrate that P-incorporated Ni-Cu, Cu-incorporated Ni-P, and Ni-incorporated Cu-P have the optimized hydrogen adsorption free energy (Δ GH*) of -0.066, -0.157, and -0.003 eV, respectively, which are more suitable than those of Ni-Cu, Ni-P, and Cu-P, respectively. The Ni-incorporated Cu-P even has a much smaller Δ GH* of -0.003 than that of Pt (∼-0.09 eV). We believe that our study will provide a new strategy to design non-noble metal alloy materials for practical applications in catalysis and energy fields.

Facile synthesis of a ZnO-BiOI p-n nano-heterojunction with excellent visible-light photocatalytic activity.

In this paper, an efficient method to produce a ZnO/BiOI nano-heterojunction is developed by a facile solution method followed by calcination. By tuning the ratio of Zn/Bi, the morphology varies from nanoplates, flowers to nanoparticles. The heterojunction formed between ZnO and BiOI decreases the recombination rate of photogenerated carriers and enhances the photocatalytic activity of ZnO/BiOI composites. The obtained ZnO/BiOI heterostructured nanocomposites exhibit a significant improvement in the photodegradation of rhodamine B under visible light (λ ≥ 420 nm) irradiation as compared to single-phase ZnO and BiOI. A sample with a Zn/Bi ratio of 3:1 showed the highest photocatalytic activity (≈99.3% after 100 min irradiation). The photodegradation tests indicated that the ZnO/BiOI heterostructured nanocomposites not only exhibit remarkably enhanced and sustainable photocatalytic activity, but also show good recyclability. The excellent photocatalytic activity could be attributed to the high separation efficiency of the photoinduced electron-hole pairs as well as the high specific area.

Novel Anisotropic Ductility of a High Strength Annealed Ti-20Zr-6.5Al-4V Alloy.

In this work, we investigate the mechanical properties of an annealed high strength Ti-20Zr-6.5Al-4V alloy in uniaxial tensile tests in different directions. The results show that the alloy exhibits obvious anisotropic ductility in different directions, while the tensile strength of the alloy remains almost unchanged. This phenomenon is closely related to α laths with similar orientations along the prior-ß grain boundaries. These α laths significantly affect the initiation and propagation of cracks when the alloy reaches its yield limit, thereby affecting the ductility of the alloy, such that it exhibits anisotropic ductility.

Effect of Sodium Dodecyl Sulphate and Sodium Bromide Additives on Ni­W Nanocoatings.

Nickel-tungsten (Ni­W) coatings were fabricated by electrodeposition method with varying quantities of sodium dodecyl sulphate and sodium bromide to examine the effects of the aforesaid additives on the coatings. The obtained nanocoatings were studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and hardness tester. The hardness, tungsten content and grain size attained a maximum value at current density of 0.15 A/cm²,0.1 A/cm² and 0.1 A/cm², respectively. There was a pronounced impact of both the additives on the microstructure and morphology of the coatings. According to results, there are considerable difference in terms of the impact caused by the additives to the tungsten content, hardness and grain size of the coatings. The obtained results suggest that hardness of coatings is mainly contributed by W content in the deposits.

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings.

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

Revisiting the glass transition and dynamics of supercooled benzene by calorimetric studies.

The glass transition and dynamics of benzene are studied in binary mixtures of benzene with five glass forming liquids, which can be divided into three groups: (a) o-terphenyl and m-xylene, (b) N-butyl methacrylate, and (c) N,N-dimethylpropionamide and N,N-diethylformamide to represent the weak, moderate, and strong interactions with benzene. The enthalpies of mixing, ΔH(mix), for the benzene mixtures are measured to show positive or negative signs, with which the validity of the extrapolations of the glass transition temperature T(g) to the benzene-rich regions is examined. The extrapolations for the T(g) data in the mixtures are found to converge around the point of 142 K, producing T(g) of pure benzene. The fragility m of benzene is also evaluated by extrapolating the results of the mixtures, and a fragility m ∼ 80 is yielded. The obtained T(g) and m values for benzene allow for the construction of the activation plot in the deeply supercooled region. The poor glass formability of benzene is found to result from the high melting point, which in turn leads to low viscosity in the supercooled liquid.