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In this study, chemically decorated surfaces are employed as tools for Artificial Pinning Centres (APC) introduction in superconducting YBa 2 Cu 3 O 7−x (YBCO) films. Self-assembled oxide nanostructures are grown on crystalline substrates via a very versatile and low-cost chemical technique called Polymer Assisted Deposition (PAD). Such decorated templates are used, in a second step, as substrates for YBCO film growth via Metal Organic Decomposition (MOD) or Pulsed Laser Deposition (PLD). The aim of the structures is to produce in the superconducting matrix strain and/or defects that should act as APCs and therefore enhance the transport properties of the samples. The oxides selected for the decoration are commonly used for the introduction of artificial pinning centres in YBCO: BaZrO 3 and ZrO 2. The decorated surfaces are analyzed via Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). YBCO films have been characterized via SEM, X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), DC resistivity and critical current measurements. The results show that the nanostructures are stable and that they can efficiently introduce strain and stacking faults in the film. This causes an increase in the value of the critical current density J c and better in-field behaviour in all the investigated field range, compared to the analogous film grown on a standard substrate, especially for chemically derived YBCO. Also J c angular dependence measurements, J c (θ), show an isotropic enhancement of the critical current for every angle of application of the field. Unlabelled Image • Surface decoration with BaZrO 3 and ZrO 2 nanoislands has been carried out via Polymer-Assisted-Deposition on single crystals • Microstructural analyses show that the nanostructured substrates can introduce strain and defects in YBa 2 Cu 3 O 7 -x films • Direct transport measurements reveal J c enhancement and better in-field behaviour for the samples grown on the nanoislands [ABSTRACT FROM AUTHOR]

The surface decoration of short-cut polyimide (PI) fibers with multi-walled carbon nanotubes (MWCNTs) was performed by fabricating a polydopamine (PDA) coating layer on the fiber surface and then immobilizing MWCNTs onto the coating layer via covalent bonding. This successful surface decoration was confirmed by scanning electron microscopy, X -ray photoelectron spectroscopy, Fourier -transform infrared microscopy and static water contact angle. The application of the surface-decorated PI fibers as reinforcing fibers for reinforcement of polycarbonate (PC)/acrylonitrile–butadiene–styrene copolymer (ABS) alloy was investigated, which indicated that the MWCNTs-decorated PI fibers not only could effectively reinforce the PC/ABS alloy but also generated a significant lightweighting effect on the resulting composites. The maximum mechanical properties were achieved for the composites at a fiber content of 20 wt.% and a fiber length of 3 mm. This significant reinforcement effect is attributed to the enhancement of interaction bonding strength between the fibers and matrix as a result of the surface decoration of PI fibers with MWCNTs. The morphological investigation suggested that fiber rupture was the major energy dissipation mechanism in the tensile and impact failures, whereas fiber debonding and pullout were partly involved in the fracture energy dissipation. In addition, the presence of surface-decorated PI fibers slightly enhanced the thermal stability and load bearing capability of composites. This work can provide a type of high-performance lightweight composite material for automobile and aviation industries. [ABSTRACT FROM AUTHOR]

A new methodology to decorate the surface of polyimide (PI) fiber with carbon nanotubes (CNTs) has been developed in this study. This surface decoration was carried out through a surface alkali treatment, a carboxylation modification, surface functionalization with acyl chloride groups and then with amino groups, and a surface graft of CNTs onto PI fiber. Fourier -transform infrared and X –ray photoelectron spectroscopic characterizations confirmed that CNTs were chemically grafted onto the surface of PI fiber, and scanning electron microscopic observation demonstrated the fiber surface was uniformly and densely covered with CNTs. The surface energy and wettability of PI fiber were improved in the presence of CNTs on the fiber surface, which made a contribution to enhance the interfacial adhesion of PI fiber with other inorganic matrices when used as a reinforcing fiber. The application of CNTs-decorated PI fiber for the reinforcement of phosphoric acid-based geopolymers was investigated, and the results indicated that the geopolymeric composites gained a noticeable reinforcement. Compared to unreinforced geopolymer, the geopolymeric composites achieved a remarkable increase in compressive strength by 120% and in flexural strength by 283%. Fractography investigation demonstrated that the interaction adhesion between the fibers and matrix was enhanced due to the surface decoration of PI fiber with CNTs, which contributed to an improvement in fracture-energy dissipation by fiber pullout and fiber debonding from the matrix. As a result, a significant reinforcement effect on geopolymeric composites was achieved through a fiber-bridging mechanism. This study provided an effective methodology to improve the interracial bonding force for PI fiber and also proves a highly efficient application of CNTs-decorated PI fiber for the mechanical enhancement of geopolymeric composites. [ABSTRACT FROM AUTHOR]

Utilizing first-principles calculations, we have investigated the structural, electronic and topological properties of binary SnSi and SnGe nanosheets as well as their H-/F-derivatives. It is found that all these systems have chair-like buckled configurations with robust structural stabilities. Unlike the elemental group-IV sheets, SnSi and SnGe sheets are narrow-band-gap semiconductors, which have a gapped Dirac cone with massive Fermions. Under the strains, a direct-to-indirect band gap transition and a semiconductor-to-metal transition would occur in these systems. Although these binary systems are trivial band insulators with ℤ 2 = 0 , their topological features can be altered by the surface decorations. Particularly, the fluorinated SiGe sheet becomes a topological insulator with ℤ 2 = 1 , and such non-trivial state can also be found in the strained fluorinated SnSi and hydrogenated SnGe sheets. Large non-trivial SOC band gaps of 0.09–0.17 eV are obtained in these 2D topological insulating systems, which will be beneficial for realizing the room-temperature quantum spin Hall effect. Our study demonstrates that binary Sn-based nanomaterials possess tunable electronic and topological properties, which have potential applications in low-power nano-electrics and devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphite (MCMB) granulates were decorated with oxygen-deficient Nb 2 O 5-x nanoparticle. • The MCMB/Nb 2 O 5-x composite electrodes show much enhanced Li+ diffusion coefficient. • The composite electrodes exhibit better rate and cycle performances than pristine MCMB. • The Nb 2 O 5-x undergoes phase transition from crystalline to amorphous with formation of NbO. • The current-sharing effect of the secondary particles may help to improve the rate performance. Nanosized oxygen-deficient orthorhombic niobium pentoxide (Nb 2 O 5-x) that possess high electronic conductivity and stable cycle performance for Li storage are uniformly deposited on the surface of mesophase carbon microspheres (MCMB), which as a whole exhibits very encouraging electrochemical Li ion storage performance, including a high specific capacity of 107 mAh g−1 at 10C (1C = 372 mA g−1) and a high capacity retention of 85.4 % after 300 cycles at 3C in the optimized case. The Li+ diffusion coefficient of the composite anode as determined by the potentiostatic intermittent titration technique (PITT) is obviously improved as compared to that of pristine MCMB. Ex situ X-ray diffraction characterizations confirm the phase transformation from orthorhombic Nb 2 O 5-x to amorphous Li y Nb 2 O 5-x accompanied by the formation of NbO through a conversion reaction in the first lithiation process. The ultrafast Li+ diffusion within the amorphous Li y Nb 2 O 5-x as well as the current-sharing effect of the secondary particles can explain the much enhanced Li ion storage property. The results of this work convincingly demonstrate that designing MCMB/Nb 2 O 5-x composite can be a more practical way to improve the energy and powder densities of Li-ion batteries rather than seeking alternative anode materials with higher capacities. [ABSTRACT FROM AUTHOR]

• Ultrathin BiOX (X = Cl, Br) nanosheets decorated with Bi and C are prepared. • Bi/C/BiOX nanosheets show excellent adsorptive and photocatalytic activity. • A recyclable photocatalytic tea-bag-like device model is proposed and fabricated. • The devices with Bi/C/BiOX photocatalysts exhibit considerable performance. Photocatalysis is considered as a promising method to solve the global water contamination crisis. However, the recycle of powdery photocatalysts is difficult to achieve, which limits their practical application. In this work, a recyclable photocatalytic tea-bag-like device model is proposed for the first time as far as we know, and applied in wastewater treatment. Meanwhile, a novel and efficient photocatalyst, the ultrathin BiOX (X = Cl, Br) nanosheets decorated with metal Bi, carbon and oxygen vacancy (Bi/C/BiOX), is prepared by a facile hydrolysis method. The decoration of Bi, carbon and oxygen vacancy vastly improve the optical response in visible region. Further, the introduction of oxygen vacancy level, surface plasmon resonance (SPR) effect of Bi and outstanding electronic conductivity of carbon synergistically accelerate the charge separation of BiOX. Moreover, the ultrathin nanosheet structure equips Bi/C/BiOX with tremendous specific surface area and abundant active sites. Thus, the Bi/C/BiOX photocatalysts exhibit excellent adsorption capacity and photocatalytic activity for the degradation of antibiotic tetracycline hydrochloride and rhodamine B. More importantly, a considerable photocatalytic performance of the tea-bag-like device model with Bi/C/BiOX is observed and there is no leakage of photocatalysts during the photocatalytic test, demonstrating its great potential for practical application in wastewater treatment. Therefore, this work not only provides a new perspective to design efficient photocatalysts, but also offers a novel strategy for photocatalysts recycling. [ABSTRACT FROM AUTHOR]

• A gentle surface engineering strategy was applied to surface decoration of β -Li x V 2 O 5. • The rate and cycling performance of β -Li x V 2 O 5 were boosted after surface modification. • The rGO/LaPO 4 /Li x V 2 O 5 composite exhibits high capacity retention of 84.1% after 100 cycles. • The multiple Li insertion activity and electrode interface was facilitated by surface decoration. The β- phase lithium vanadium oxide bronze (β- Li x V 2 O 5) with high theoretic specific capacity up to 440 mAh g−1 is considered as promising cathode materials, however, their practical application is hindered by its poor ionic and electronic conductivity, resulting in unsatisfied cyclic stability and rate capability. Herein, we report the surface decoration of β- Li x V 2 O 5 cathode using both reduced oxide graphene (rGO) and ionic conductor LaPO 4 , which significantly promotes the electronic transfer and Li+ diffusion rate, respectively. As a result, the rGO/LaPO 4 /Li x V 2 O 5 composite exhibits excellent electrochemical performance in terms of high reversible specific capacity of 275.7 mAh g−1 with high capacity retention of 84.1% after 100 cycles at a current density of 60 mA g−1, and acceptable specific capacity of 170.3 mAh g−1 at high current density of 400 mA g−1. The cycled electrode is also analyzed by electrochemical impedance spectroscopy, ex-situ X-ray diffraction and scanning electron microscope, providing further insights into the improvement of electrochemical performance. Our work provides an effective approach to boost the electrochemical properties of lithium vanadates for practical application in lithium ion batteries. [ABSTRACT FROM AUTHOR]