Bifunctional Square-Planar NiO4 Coordination of Topotactic LaNiO2.0 Films for Efficient Oxygen Evolution Reaction.

The high-efficient and low-cost oxygen evolution reaction (OER) is decisive for applications of oxide catalysts in metal-air batteries, electrolytic cells, and energy-storage technologies. Delicate regulations of active surface and catalytic reaction pathway of oxide materials principally determine thermodynamic energy barrier and kinetic rate during catalytic reactions, and thus have crucial impacts on OER performance. Herein, a synergistic modulation of catalytically active surface and reaction pathway through facile topotactic transformations switching from perovskite (PV) LaNiO3.0 film to infinite-layer (IL) LaNiO2.0 film is demonstrated, which absolutely contributes to improving OER performance. The square-planar NiO4 coordination of IL-LaNiO2.0 brings about more electrochemically active metal (Ni+ ) sites on the film surface. Meanwhile, the oxygen-deficient driven PV- IL topotactic transformations lead to a reaction pathway converted from absorbate evolution mechanism to lattice-oxygen-mediated mechanism (LOM). The non-concerted proton-electron transfer of LOM pathway, evidenced by the pH-dependent OER kinetics, further boosts the OER activity of IL-LaNiO2.0 films. These findings will advance the in-depth understanding of catalytic mechanisms and open new possibilities for developing highly active perovskite-derived oxide catalysts.

Organic Electrochemical Transistor with MoS2 Nanosheets Modified Gate Electrode for Sensitive Glucose Sensing.

An organic electrochemical transistor (OECT) with MoS2 nanosheets modified on the gate electrode was proposed for glucose sensing. MoS2 nanosheets, which had excellent electrocatalytic performance, a large specific surface area, and more active sites, were prepared by liquid phase ultrasonic exfoliation to modify the gate electrode of OECT, resulting in a large improvement in the sensitivity of the glucose sensor. The detection limit of the device modified with MoS2 nanosheets is down to 100 nM, which is 1~2 orders of magnitude better than that of the device without nanomaterial modification. This result manifests not only a sensitive and selective method for the detection of glucose based on OECT but also an extended application of MoS2 nanosheets for other biomolecule sensing with high sensitivity.

Facile synthesis of hierarchical MoS2/ZnS @ porous hollow carbon nanofibers for a stable Li metal anode.

Lithium metal is considered as an ideal anode candidate for next generation Li battery systems since its high capacity, low density, and low working potential. However, the uncontrollable growth of Li dendrites and infinite volume expansion impede the commercialized applications of Li-metal anodes. In this work, we rationally designed and constructed a hierarchical porous hollow carbon nanofiber decorated with diverse metal sulfides (MS-ZS@PHC). This composite scaffold has three advantages: First, the synergistic effect of multiple-size lithiophilic phases (nano ZnS and micro MoS2) can regulate Li ions nuclei and grow up homogenously on the scaffold. Second, the enlarged interplanar spacing of MoS2 microsphere on the fibers can provide abundant channels for Li ions transportation. Third, the porous scaffold can confine the volume expansion of Li metal anode during cycling. Therefore, in a symmetrical cell, the MS-ZS@PHC host presents a homogenous Li plating/stripping behavior and runs steadily for 1100 h at 5 mA cm-2 with a capacity of 5 mAh cm-2 and even for 700 h at 10 mA cm-2 with a capacity of 1 mAh cm-2. A full cell using MS-ZS@PHC /Li composite as anode and coupled with LiFePO4 as cathode delivers an excellent cyclic and rate performances.

Ascorbic acid-mediated organic photoelectrochemical transistor sensing strategy for highly sensitive detection of heart-type fatty acid binding protein.

Heart-type fatty acid binding protein (H-FABP) has been regarded as a promising biomarker for early diagnosis of acute myocardial infarction (AMI). Developing fast and reliable method for H-FABP detection is still highly desirable but challenging. Herein, an ascorbic acid (AA)-mediated organic photoelectrochemical transistor (OPECT) sensing strategy was reported for the detection of H-FABP in phosphate buffer saline (PBS) solution and human serum. A primary antibody/H-FABP/secondary antibody-Au NPs-alkaline phosphatase (ALP) sandwich immunorecognition structure was constructed. The modified ALP could catalytically convert ascorbic acid-2-phosphate to AA, which was then analyzed by OPECT. As a result, the AA-mediated OPECT sensing strategy realized highly sensitive detection of H-FABP with a detection limit of 3.23 × 10-14 g/mL which is two orders of magnitude lower than that of PEC method. Under optimal experimental conditions, H-FABP concentration could be obtained in ∼90 min. Importantly, the analysis of H-FABP was resistant to the interference from immunoglobulin G, bovine serum albumin, cysteine, AA and human serum. The proposed AA-mediated OPECT sensing strategy provides a simple, fast, and accurate way for H-FABP detection in AMI suspected patients.

Metal organic framework-coated gold nanorod as an on-demand drug delivery platform for chemo-photothermal cancer therapy.

Chemo-photothermal therapy based on nanoparticles has emerged as a promising strategy for cancer treatment. However, its therapeutic efficacy and application potential are largely subjected to the uncontrollability and biotoxicity of functional nanoplatforms. Herein, a novel biocompatible and biodegradable metal organic framework (MOF), which was constructed by growing crystalline zeolitic imidazolate framework-8 on gold nanoroad (Au@ZIF-8), was designed and fabricated for efficient drug loading and controlled release. Owing to the large surface area and guest-matching pore size of ZIF-8, doxorubicin (DOX) was successfully loaded into the Au@ZIF-8 with a high drug loading efficiency of ~ 37%. Under NIR light or weakly acidic environment, the ZIF-8 layer was quickly degraded, which resulted in an on-demand drug release in tumour site. More importantly, under the irradiation of near infrared (NIR) laser, highly efficient cancer treatment was achieved in both in vitro cell experiment and in vivo tumour-bearing nude mice experiment due to the synergistic effect of photothermal (PTT) therapy and chemotherapy. In addition, the in vivo study revealed the good biocompatibility of Au@ZIF-8. This work robustly suggested that Au@ZIF-8 could be further explored as a drug delivery system for chemo-photothermal synergistic therapy.

A Highly Strained Phase in PbZr0.2Ti0.8O3 Films with Enhanced Ferroelectric Properties.

Although epitaxial strain imparted by lattice mismatch between a film and the underlying substrate has led to distinct structures and emergent functionalities, the discrete lattice parameters of limited substrates, combined with strain relaxations driven by film thickness, result in severe obstructions to subtly regulate electro-elastic coupling properties in perovskite ferroelectric films. Here a practical and universal method to achieve highly strained phases with large tetragonal distortions in Pb-based ferroelectric films through synergetic effects of moderately (≈1.0%) misfit strains and laser fluences during pulsed laser deposition process is demonstrated. The phase possesses unexpectedly large Poisson's ratio and negative thermal expansion, and concomitant enhancements of spontaneous polarization (≈100 µC cm-2) and Curie temperature (≈800 °C), 40% and 75% larger than that of bulk counterparts, respectively. This strategy efficiently circumvents the long-standing issue of limited numbers of discrete substrates and enables continuous regulations of exploitable lattice states in functional oxide films with tightly elastic coupled performances beyond their present levels.

Polyvinyl Alcohol/Graphene Oxide Interlayer for Enhancing Adhesive Performance of HA Coating on C/C Composites Prepared by Hydrothermal Electrodeposition/Hydrothermal Treatment.

Hydroxyapatite (HA) coatings directly deposited by hydrothermal electrochemical technology (HET) onto carbon/carbon (C/C) composites exhibited a catastrophic failure occurring at the interface of the HA and C/C. To overcome this problem, a polyvinyl alcohol (PVA)/graphene oxide (GO) interlayer (P/G interlayer) was applied on the (NH4)2S2O8-pretreated C/C substrate (named P/G-C/C) by using a dipping method. Subsequently, a calcium phosphate coating was deposited on P/G-C/C, shortened as M-P/G-C/C, by HET, and then converted into HA coating (abbreviated as HA-P/G-C/C) through posthydrothermal treatment. For comparison, HA coating was prepared onto C/C without a P/G interlayer through the same process, which was denoted as HA-C/C. The composition, microstructure, and morphology of the samples were characterized by X-ray diffractometry (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), Raman spectra, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). The adhesive performance of the coatings on C/C was measured by a scratch test. Finally, an in vitro bioactivity of the coatings was evaluated in a simulated body fluid solution at 37 °C. Results showed no apparent differences in the morphology and phase of the posttreated coatings, both of which are composed of a dense structure containing needle-like HA crystals. However, the HA-P/G-C/C sample possessed a higher Ca/P ratio and denser interface, thereby exhibiting higher adhesive performance and better bioactivity. The adhesive strength of the HA-P/G coating was observed at a critical load of 41.04 N, which increased by 29.3% relative to the HA coating. Moreover, the failure site was on the HA-P/G coating rather than at the interface. The enhanced adhesive performance was ascribed to the PVA/GO-repairing pits on C/C and PVA and GO toughening effects on the HA coating. In vitro and in vivo tests revealed no statistical significance for the two HA-coated C/C samples, although the HA-P/G coating exhibited better bioactivity, inducing the growth of bonelike apatite than the HA coating.

Defect-rich honeycomb-like nickel cobalt sulfides on graphene through rapid microwave-induced synthesis for ultrahigh rate supercapacitors.

Nickel cobalt sulfides (NCS) are regarded as potential energy storage materials due to the versatile valent states and rich electrochemical activity, but their sluggish synthesis process and inferior rate performance hinder them from large-scale application. Herein, microwave-induced strategy has been employed for efficient synthesis of honeycomb-like NCS/graphene composites, which are explored as ultrahigh rate battery-type electrodes for supercapacitors. Due to the internal heat mechanism, the synthesis time of NCS by microwave could be shortened from hours to minutes. Density functional theory was simulated to uncover the interfacial effect between NCS and graphene, and the resulted Schottky barrier is in favor of enhancing redox activity and capacity. Ultimately, the obtained defect-rich nickel cobalt sulfides/graphene with thermal treatment (NCS/G-H) could exhibit a high specific capacitance of 1186 F g-1 at 1 A g-1 and sustain 89.8% capacity even after the increase of current density over 20 times, which is much superior to bare NCS and NCS/graphene. Furthermore, the assembled NCS/G-H hybrid supercapacitor delivers supreme energy density of 46.4 Wh kg-1, and retains outstanding long-term stability of 89.2% after 10 k cycles. These results indicate that the synthesized NCS/G-H by time-saving microwave-induced liquid process could be served as high rate materials for supercapacitors.

Synthesis of Ni@NiSn Composite with High Lithium-Ion Diffusion Coefficient for Fast-Charging Lithium-Ion Batteries.

To solve the problems of fast-charging of lithium-ion batteries in essence, development of new electrode materials with higher lithium-ion diffusion coefficients is the key. In this work, a novel flower-like Ni@SnNi structure is synthesized via a two-step process design, which consists of the fabrication of Ni cores by spray pyrolysis followed by the formation of SnNi shells via a simple oxidation-reduction reaction. The obtained Ni@SnNi composite exhibits an initial capacity of ≈693 mA h g-1 and a reversible capacity of ≈570 mA h g-1 after 300 charge/discharge cycles at 0.5 C, and maintains 450 mA h g-1 even at a high rate of 3 C. Further, it is proved that a Ni@SnNi composite possesses high lithium-ion diffusion coefficient (≈10-8), which is much higher than those (≈10-10) reported previously, which can be mainly attributed to the unique flower-like Ni@SnNi structure. In addition, the full cell performance (Ni@SnNi-9h/graphite vs LiCoO2) with a capacity ratio of 1.13 (anode/cathode) is also tested. It is found that even at 2 C rate charging/discharging, the capacity retention at 100 cycles is still close to 89%. It means that Ni@SnNi-9h is a promising anode additive for lithium-ion batteries with high energy density and power density.

g-C3N4/Pt/BiVO4 nanocomposites for highly efficient visible-light photocatalytic removal of contaminants and hydrogen generation.

Inspired by natural photosynthesis, artificial heterojunction photocatalysts have been extensively studied. Herein, a novel ternary graphitic carbon nitride/platinum/bismuth vanadate (g-C3N4/Pt/BiVO4) photocatalytic system was successfully synthesized, where Pt/BiVO4 nanosheet is anchored on the surface of layered g-C3N4, as evidenced by structural observations. Ultraviolet photoelectron spectroscopy and ultraviolet-visible diffuse reflectance spectroscopy are carried out to identify the position of the conduction band and valence band. A Z-scheme is used to interpret the superior photocatalytic performance of g-C3N4/Pt/BiVO4 and further verified by the capture of free radicals and terephthalic acid photoluminescence experiments. Compared with the g-C3N4/BiVO4 binary system, the Z-scheme g-C3N4/Pt/BiVO4 photocatalyst not only possesses enhanced carrier separation efficiency but also maintains sufficient redox properties, thus inducing superior photocatalytic activity. More importantly, the novel Z-scheme photocatalyst exhibits excellent recycle stability, which could provide inspiration for the rational design of efficient and practical photocatalysts for environmental pollution treatment. The ternary photocatalyst also exhibits significantly enhanced visible-light photocatalytic hydrogen production performance.

Al-based metal organic framework derived self-assembled carbon nanosheets as innovative anodes for Li- and Na-ion batteries.

Functional modification and structural design of carbon electrode materials are considered as a cost-effective method to improve their electrochemical performance. In this study, a solvothermal method is applied to realize self-assembly of the metal-organic framework. After simple carbonization and acid treatment, carbon nanosheets with 2D adjustable defective sub-units are successfully prepared for the first time. It is found that carbonization temperature has a significant effect on the carbon skeleton structure. The optimal nanostructures with large specific surface area and appropriate pore size distribution make self-assembled carbon nanosheets having excellent Li/Na-ion storage properties. In addition, the adjustable carbon skeleton structure can effectively avoid irreversible damage when charge-discharge cycles. For Li-ion batteries, a specific capacity of 825 mAh g-1 is achieved after 100 cycles at 100 mA g-1, while for Na-ion batteries a specific capacity of 193 mAh g-1 is observed after 100 cycles at 100 mA g-1. Moreover, for Na-ion batteries, even at a high rate of 1000 mA g-1 the material delivers a specific capacity of 109.5 mAh g-1 after 3500 cycles.

Antibacterial and antioxidant activity of exopolysaccharide mediated silver nanoparticle synthesized by Lactobacillus brevis isolated from Chinese koumiss.

Recently, silver nanoparticles gain significant attention due to their applications in various fields. The aim of present study was to develop the eco-friendly, cost effective, and simple method to biosynthesized the silver nanoparticle using sliver nitrate as precursor. In this study, we investigated the physical characterization and biotechnological applications of biosynthesized silver nanoparticle using exopolysaccharide of probiotic Lactobacillus brevis MSR104 isolated from Chinese koumiss. Biosynthesized silver nanoparticles were characterized using the fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and elemental analyzer. The achieved results indicate that silver nanoparticles varied in sized with an average size of 45 nm. The X-ray diffraction analysis results showed that the silver nanoparticles have a crystalline nature. The results of antimicrobial assay indicated that the silver nanoparticles exhibited outstanding antimicrobial activity in dose dependent manner against both Gram's negative as well as Gram's positive. The antioxidant results indicate that the silver nanoparticles showed excellent scavenging rate against DPPH free radicals (81.4 ±â€¯1.2%) and nitric oxide free radicals (75.06 ±â€¯0.4%). Furthermore, the results of MTT assay revealed that the AgNPs significantly reduced the percentage of live HT-29 cells at higher concentration. This study concluded that the newly synthesized silver nanoparticles have antibacterial, antioxidant, and anticancer applications in agricultural and food industries.

Robust, Reprocessable, and Reconfigurable Cellulose-Based Multiple Shape Memory Polymer Enabled by Dynamic Metal-Ligand Bonds.

Smart materials with multiple shape memory capacities have gradually attracted the interest of a lot of researchers due to their potential application in textiles, smart actuators, and aerospace engineering. However, the design and sustainable synthesis of multiple shape memory polymers (SMPs) simultaneously possessing robust mechanical strength, reprocessability, and reconfigurability still remain full of challenges. Starting from a readily available biomass material cellulose, a well-defined SMP, cellulose-graft-poly(n-butyl acrylate-co-1-vinylimidazole) copolymer (Cell-g-(BA-co-VI)) was facilely synthesized by addition-fragmentation chain transfer polymerization (RAFT) and the subsequent metallosupramolecular cross-linking. Taking advantage of the dynamic bonding, i.e., the rapid reversible fragmentation and the formation of metal ion-imidazole coordination, polymer networks with highly tunable mechanical properties, excellent solid-state plasticity, and quadruple-shape memory capacity are handily attainable. Microscopically, the metal-ligand clusters have a strong tendency to phase segregate from the soft grafted copolymers indicated by atomic force microscopy (AFM), and these serve as netpoints to construct novel SMPs. This article represents our new exploration of the next-generation SMPs based on cellulose backbone where carrying with supramolecular cross-linked soft grafted copolymers. This architecture design allows achieving robust, reprocessable, and reconfigurable thermoplastic SMPs that are difficult to realize by many other methods. Integrating these properties into one system in a synergetic manner also provides a novel approach to the high value addition application of cellulose in the fabrication of advanced functional materials.

A Novel Bi2MoO6/ZIF-8 Composite for Enhanced Visible Light Photocatalytic Activity.

A series of novel Bi2MoO6/zeolitic imidazolate framework-8 (ZIF-8) photocatalysts have been successfully fabricated through a facile self-assembly process. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectrophotometry, and X-ray photoelectron spectroscopy (XPS) characterized pure Bi2MoO6, pure ZIF-8, and a series of Bi2MoO6/ZIF-8 composites. The result indicated that, when compared with pure Bi2MoO6, the composite of Bi2MoO6/ZIF-8 exhibited excellent photocatalytic performance for the degradation of methylene blue (MB) under visible light. Moreover, the Bi2MoO6/ZIF-8-3 composite (the molar ratio of Bi2MoO6 to 2-MI is 3:3) has optimum photocatalytic performance because of the suitable amount of ZIF-8 decorated on the flower-like Bi2MoO6. The enhanced photocatalytic activity is probably due to the introduction of ZIF-8, which will promote the separation of electron-hole pair and the surface morphology. Benefitting from the diversity of the MOF species (ZIF-8 is one of them), this composing strategy of Bi2MoO6/MOF composite would provide new insight into the design of highly efficient visible light photocatalysts.

High-performance supercapacitors based on hierarchically porous carbons with a three-dimensional conductive network structure.

Clews of polymer nanobelts (CsPNBs) have the advantages of inexpensive raw materials, simple synthesis and large output. Novel clews of carbon nanobelts (CsCNBs) have been successfully prepared by carbonizing CsPNBs and by KOH activation subsequently. From the optimized process, CsCNBs*4, with a specific surface area of 2291 m2 g-1 and a pore volume of up to 1.29 cm3 g-1, has been obtained. Fundamentally, the CsCNBs possess a three-dimensional conductive network structure, a hierarchically porous framework, and excellent hydrophilicity, which enable fast ion diffusion through channels and a large enough ion adsorption/desorption surface to improve electrochemical performance of supercapacitors. The product exhibits a high specific capacitance of 327.5 F g-1 at a current density of 0.5 A g-1 in a three-electrode system. The results also reveal a high-rate capacitance (72.2% capacitance retention at 500 mV s-1) and stable cycling lifetime (95% of initial capacitance after 15 000 cycles). Moreover, CsCNBs*4 provides a high energy density of 29.8 W h kg-1 at a power density of 345.4 W kg-1 in 1 M tetraethylammonium tetrafluoroborate/acetonitrile (TEABF4/AN) electrolyte. These inspiring results imply that this carbon material with a three-dimensional conductive network structure possesses excellent potential for energy storage.

Facile fabrication of highly efficient ETL-free perovskite solar cells with 20% efficiency by defect passivation and interface engineering.

Tetramethylammonium hydroxide (TMAH) is employed to modify the surface and electrical properties of fluorine-doped tin oxide (FTO) electrodes in perovskite solar cells. Synchronously, owing to the flow of unbound TMA+ ions into the perovskite, the trap density of the perovskite overlayer is largely reduced. Conductivity of the grain boundaries in the perovskite layer is also greatly increased. A high efficiency of 20.1% along with a reduced J-V hysteresis in our champion perovskite solar cells without electron transport layers is achieved.

Boosting the Yield of MXene 2D Sheets via a Facile Hydrothermal-Assisted Intercalation.

Ti3C2T x (MXene) exhibits attractive properties in different applications. However, traditional synthesis leads to unsatisfactory yield of two-dimensional (2D) Ti3C2T x, e.g., lower than 20%, which stems from the strong interactions of potential Ti-Ti bonds and residual Ti-Al bonds between the adjacent Ti3C2 layers, hindering the effective intercalation and delamination. Herein, we propose a facile hydrothermal-assisted intercalation (HAI) strategy to boost the yield of 2D sheets, achieving a record high value of 74%. This HAI assists the diffusion and intercalation of reagent effectively, promoting the subsequent delamination; meanwhile, an antioxidant is applied to protect these Ti3C2T x from oxidation during the HAI process. Therefore, massive Ti3C2T x 2D sheets can be easily synthesized. Thanks to the synergistic effect of high conductivity and substantial terminated functionalities, these Ti3C2T x 2D sheets show promising application in supercapacitor, providing a high capacitance of 482 F g-1. Besides, the ultrafast carrier dynamics results of Ti3C2T x 2D sheets clearly imply the promising application in photocatalysis due to the relatively long bleaching relaxation time. Our work not only paves the way for the mass production of Ti3C2T x 2D sheets but also provides insights into their electronic and optical properties.

Microwave-assisted rapid preparation of hollow carbon nanospheres@TiN nanoparticles for lithium-sulfur batteries.

Highly conductive titanium nitride (TiN) has a strong anchoring ability for lithium polysulfides (LiPSs). However, the complexity and high cost of fabrication limit their practical applications. Herein, a typical structure of hollow carbon nanospheres@TiN nanoparticles (HCNs@TiN) was designed and successfully synthesized via a microwave reduction method with the advantages of economy and efficiency. With unique structural and outstanding functional behavior, HCN@TiN-S hybrid electrodes display not only a high initial discharge capacity of 1097.8 mA h g-1 at 0.1C, but also excellent rate performance and cycling stability. After 200 cycles, a reversible capacity of 812.6 mA h g-1 is still retained, corresponding to 74% capacity retention of the original capacity and 0.13% decay rate per cycle, which are much better than those of HCNs-S electrodes.

Organic Photo-Electrochemical Transistor-Based Biosensor: A Proof-of-Concept Study toward Highly Sensitive DNA Detection.

Organic bioelectronics have shown promising applications for various sensing purposes due to their significant advantages in term of high flexibility, portability, easy fabrication, and biocompatibility. Here, a new type of organic device, organic photo-electrochemical transistor (OPECT), is reported, which is the combination of an organic electrochemical transistor and a photo-electrochemical gate electrode modified with CdS quantum dots (QDs). Thanks to the inherent amplification function of the transistor, the OPECT-based biosensor exhibits much higher sensitivity than that of a traditional biosensor. The sensing mechanism of the OPECT is attributed to the charge transfer between the photosensitive semiconductor CdS QDs and the gate electrode. In an OPECT-based DNA sensor, target DNA is labeled with Au nanoparticles (NPs) and captured on the gate electrode, which can influence the charge transfer on the gate caused by the exciton-plasmon interactions between CdS QDs and Au NPs. Consequently, a highly sensitive and selective DNA sensor with a detection limit of around 1 × 10-15 m is realized. It is expected that OPECTs can be developed as a high-performance platform for numerous biological detections in the future.

Evolving mechanism of organotemplate-free hierarchical FAU zeolites with house-of-card-like structures.

Hierarchical FAU zeolites with house-of-card-like (HCL) structures were synthesized through a one-pot organotemplate-free route in the Na2O-Al2O3-SiO2-H2O system. The structure details and formation mechanism of HCL zeolites were determined by the combination of electron crystallography and synthesis chemistry. The results revealed that the unique HCL morphology was attributed to large solution viscosity, and the evolution process obeyed a skeleton crystal growth model due to the limited vortexing effect, which was different from those of the HCL zeolites obtained using organic templates.