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The development of hydrogen–oxygen fuel cells with an alkaline electrolyte was highly limited by the sluggish kinetics of the hydrogen oxidation reaction (HOR). Here, with a pyrolysis-reduction route, a new RuNi-based electrocatalyst was prepared, which presents an ultrathin nanowire-like structure. In alkaline media, this catalyst shows an excellent catalytic performance with an exchange current density of 1.10 mA cm−2disk for hydrogen oxidation. The exchange current density and mass activity of this catalyst are much higher than those of its single-metal counterparts and even the commercial Pt/C catalyst containing 20% Pt. Such a remarkable catalytic activity can be explained by the interaction between Ru and Ni; the incorporation of Ni may induce an electronic effect on the optimization of the Ru–Had strength and provide a functional surface that can absorb OH species, thus boosting the catalytic activity. These findings may cast a new light on the exploration of low-cost but high-efficiency catalysts for fuel cells. [ABSTRACT FROM AUTHOR]

Dual-confined porous Si@c-ZIF@carbon nanofibers (Si@c-ZIF@CNFs) are fabricated that possess excellent antioxidant capacity, high surface area and abundant pores, which enhances conductivity, relieves volume expansion and facilitates electrolyte penetration during cycling. When evaluated as self-supporting anodes for lithium-ion batteries, the Si@c-ZIF@CNFs exhibit excellent cycling and rate performance. [ABSTRACT FROM AUTHOR]

Electrocatalytic oxidation has been proven as a sustainable and promising alternative to traditional chemical transformation, but its further development is limited by the use of noble-metal electrocatalysts. Herein, a polyoxometalate-based electrode material, H5PMo10V2O40@CTF (denoted as PMo10V2@CTF), has been successfully fabricated through electrostatic assembly of a molecular polyoxometalate catalyst, PMo10V2, with a porous cationic covalent triazine framework (CTF), which, to our knowledge, represents the first combination of polyoxometalate with a cationic CTF. The resulting PMo10V2@CTF exhibits high activity for the selective electrocatalytic oxidation of alcohols to aldehydes, achieving 99% conversion of benzyl alcohol, over 99% selectivity of benzyl aldehyde, and at the same time near unity H2 production. Notably, the reported electrocatalytic system presents good atom economy, high energy conversion (96% faradaic efficiency), remarkable catalytic activity and robustness for at least eight recycles. Based on the various experimental and spectroscopic analyses, a possible catalytic mechanism was proposed, revealing that such excellent electrocatalytic performance is attributed to the versatile redox ability of PMo10V2 and the good porosity and adsorption property of the CTF in the constructed PMo10V2@CTF composite. [ABSTRACT FROM AUTHOR]

Chitosan (CS) based nanofibrous membranes were fabricated via hybrid electrospinning of chitosan (CS) and poly(ε-caprolactone) (PCL) or poly(ε-caprolactone)-block-poly(ethylene glycol) (PCL-b-PEG) copolymers for the adsorption of dyes from aqueous solution. The amphiphilic block polymers were obtained by polymerization of PCL and different molecular weights of PEG. It was observed that the secondary fiber and core–shell structure could be controlled by PEG segments. The results of XPS showed that as the molecular weight of the PEG segments increased, the content of CS on the fiber surface increased. The parameters of adsorption time, initial concentration and pH values on the adsorption capacity were studied. The adsorption experiments showed that the adsorption process toward Congo red (CR) on CS-based membranes fitted well with the pseudo-second-order model and Langmuir isotherm model. The CS-based membranes with PEG molecular weight of 5 kDa possessed good reusability and the maximum adsorption capacity calculated from the Langmuir model was 291.55 mg g−1. The existence of intermolecular hydrogen bonds between CS and PCL-b-PEG copolymer reduced the loss of CS. Therefore, CS-based membranes would be promising materials for water remediation. [ABSTRACT FROM AUTHOR]

Surface oxidation frequently occurs in non-oxide antimony chalcogenides, which is a double-edged sword for their (opto)electronic properties and applications. Here we report that the photoelectronic performance of Sb2Se3 nanorods (NRs) can be improved through an appropriate degree of surface oxidation. During the synthesis, the volume ratio of oleic acid (OA)/oleylamine (OLA) was varied to control the oxidation degrees of the Sb2Se3 NRs, which span 1.20–51.49% with increasing OA ratio as revealed by X-ray photoelectron spectroscopy (XPS) analysis. A medium level of surface oxidation, typically 20–30% found here, is beneficial to the enhancement of the photocurrent, on/off ratios and photostability of the Sb2Se3 NRs when evaluated in a sandwich-type ITO/Sb2Se3/ITO photoconductor device. Surface hydroxylation, which is boosted by the presence of Sb–oleate and trace H2O remaining in the reaction system, is suggested to facilitate the formation of Sb–OH bonds and the OA-volume dependent oxidation at the surface of Sb2Se3. [ABSTRACT FROM AUTHOR]

Composition engineering is an active topic of research for optical and electronic (nano)crystals and functional materials. We here demonstrate the control over the ratios and distributions of selenium and sulfur in ternary Sb2(Se,S)3 alloy nanorods (NRs), which were synthesized from a molecular chalcogen precursor, selenium disulfide (SeS2). By increasing the anion/cation precursor ratios (SeS2/SbCl3) from 0.5 : 1 to 1 : 1 and 1.5 : 1, an increase in both the Se fractions and the lengths × diameters of NRs is achieved with the Se and S distributions in Sb2(Se,S)3 varying from homogeneity to inhomogeneity. Within the inhomogeneous NRs obtained at high SeS2/SbCl3 ratios containing excessive chalcogen (Se + S), S decreases but Se increases from the center to the periphery as revealed by EDS elemental analyses performed on individual NRs. In particular, the 1D growth anisotropy of NRs allows for a large chalcogen concentration gradient along the axial direction of the resulting NRs from their middle to the two ends. Such non-uniform Se and S distributions can be rationally interpreted by analyzing the growth kinetics and processes of Sb2(Se,S)3 NRs and would give rise to uncommon (opto)electronic properties towards future nanowire-based devices. [ABSTRACT FROM AUTHOR]

Stibnite (Sb2S3) is a promising material in photoelectronic and energy devices, but it frequently exhibits sheaf-like and hierarchical-like structures that consist of secondary nanorods (NRs) or nanowires (NWs) because of its spatial fractal splitting growth habit. Foreign ions or seeds enable the alteration of the growth dynamics and the consequent shape engineering of nanocrystals. We here report that the introduction of trace amounts of isovalent Bi3+ ions (typically 1–2 atom% Bi/Sb) is efficient to synthesize highly disperse, uniform Sb2S3 NRs with reduced diameters and lengths. Two temperature-dependent growth mechanisms stemming from the presence of Bi ions, the full splitting growth at high temperature and the seeded growth at low temperature, are proposed to demonstrate the formation of separated, thinner NRs. Meanwhile, the surfactant removal and the coupling with p-type CuSCN are simultaneously performed on these Sb2S3 NRs, and the resultant CuSCN/Sb2S3 composite, which contains a large amount of point-to-surface contact p–n heterojunctions with a suitable band alignment, holds promise in self-powered UV-visible photodetectors via the photovoltaic effect. [ABSTRACT FROM AUTHOR]

Aiming to impart epoxy resin (EP) with super-efficient fire safety, organically modified layered double hydroxide (LDH-DBS) nanosheets were surface-assembled by an ultrafine Ni(OH)2 nanocatalyst via circular coordination-induced growth. LDH-DBS@Ni(OH)2 was designed to exploit a spatial-dependent catalytic strategy to strengthen the interfacial structure between the LDH nanosheets and the EP matrix during a dynamic charring process. Adaquate characterization verified the successful preparation of LDH-DBS@Ni(OH)2, with Ni(OH)2 nanocrystals uniformly distributed on the LDH nanosheets. LDH-DBS@Ni(OH)2 presented better nano-dispersion in an EP matrix relative to LDH-DBS. The results illustrate that a mere 3 wt% of LDH-DBS@Ni(OH)2 imparted the EP matrix with a value of UL-94 V-0. The peak heat release rate and total smoke production at 200 s were reduced by 60.6% and 66.5%, respectively, upon the addition of 3 wt% LDH-DBS@Ni(OH)2, accompanied by tremendously suppressed CO production. In parallel, the thermal degradation analysis revealed that the interfacial growth of the Ni(OH)2 nanocatalyst resulted in a significant reduction in volatiles, including CO, and aliphatic and aromatic compounds. A further investigation of the mechanism by dynamic charring analysis revealed the remarkable contribution of interfacial-charring catalysis to the reinforcement of the intumescent char structure and fire safety. In perspective, the interfacial-catalytic assembly of nanomaterials without traditional fire-retardant elements opens up a novel window and scale-up prospects for the production of polymers with super-efficient fire safety properties. [ABSTRACT FROM AUTHOR]

To further improve the catalytic carbonization efficiency of polymer composites for the formation of compact protective layers in the combustion process, a novel type of Fe-CNTs was prepared in large scale. The Fe-CNTs were used as nanofillers to efficiently improve catalytic carbonization, flame retardancy, and mechanical performances of epoxy resin (EP). With the incorporation of 6 wt% Fe-CNTs, the LOI value of the EP/Fe-CNTs nanocomposites was improved to 35.0 and the UL-94 V-1 rating was passed with an average (t1 + t2) value of 13.3. As compared to pure EP, the PHRR, THR, and TSP of EP/6 wt% Fe-CNTs nanocomposites decreased by 30.7%, 39.1%, and 48.6%, respectively. The significantly improved flame retardancy could be attributed to the compact carbonaceous ceramic layers, which significantly retarded the transfer of heat and combustible gas between the EP nanocomposites and the flame zone. Moreover, the EP/Fe-CNTs nanocomposites exhibited excellent impact and tensile strength performances due to the formation of a strong three-dimensional network structure in the EP matrix. [ABSTRACT FROM AUTHOR]

Resource utilization of waste plastic could solve the problem of environmental pollution and simultaneously relieve energy shortages, achieving sustainable development. In this study, the conversion of waste polytetrafluoroethylene (PTFE) to cubic silicon carbide (SiC) nanoparticles has been described. The structures and morphologies of the obtained SiC were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, the FTIR spectrum of the obtained SiC sample suggests that the waste PTFE was completely converted into SiC in our approach. [ABSTRACT FROM AUTHOR]

To tackle the issue of the low specific capacity (372 mA h g−1) of graphite as the anode material for lithium-ion batteries (LIBs), an effective and controllable strategy was developed to construct porous bimetallic Co/Zn embedded N-doped carbon (Co–Zn/N–C) polyhedral nanocages via annealing a ZIF-8@ZIF-67 precursor at 800 °C under Ar atmosphere. The results clearly displayed that metallic Co and Zn particles are uniformly dispersed in the carbon matrix. Porous Co–Zn/N–C polyhedral nanocages have a large specific surface area of 349.12 m2 g−1 and contain plenty of micropores and mesopores, which benefit from the carbonization of organic ligands and the catalytic effect of cobalt in the calcination process. As anodes for LIBs, the porous Co–Zn/N–C polyhedral nanocages showed an initial discharge capacity of 809 mA h g−1 and a capacity retention of 702 mA h g−1 after 400 cycles at a current density of 0.2 A g−1. Furthermore, a reversible capacity of 444 mA h g−1 was obtained at a much higher current density of 2 A g−1. The improved electrochemical performance was attributed to the synergistic effect of Zn and Co, the unique porous hollow structure as well as N doping, which relieved the impact of volume changes, maintained perfect electrical conductivity throughout the electrode and enhanced the electrochemical activities of lithium storage. [ABSTRACT FROM AUTHOR]

Huge consumption of thermoplastic polyurethane (TPU) results in two serious challenges for our society: fire hazards and environment pollution. To address these challenges, on the one hand, ultrathin β-Co(OH)2 nanosheets were devised and synthesized by a surfactant self-assembly technique and their application in TPU reduced the fire hazard; on the other hand, a green method was developed to sustainably recycle TPU nanocomposites into high value-added carbon materials. The structural characterizations demonstrate that the ultrathin β-Co(OH)2 nanosheets showed a typical two-dimensional lamellar morphology, possessing a lateral dimension of ca. 2 μm and a low thickness of ca. 2.6 nm, corresponding to the two layers of β-Co(OH)2. The incorporation of ultrathin β-Co(OH)2 nanosheets into the TPU matrix effectively reduced the heat release and restrained the toxicity of the volatiles, which was attributed to the ultrathin β-Co(OH)2 nanosheets in the TPU matrix offering an enhanced barrier effect and catalytic charring capability and Co3O4 decomposed from β-Co(OH)2 possessing superior catalytic oxidation of CO. Moreover, a green autocatalytic process in a sealed autoclave was developed to convert TPU/Co(OH)2 nanocomposites into high value-added Co/CNTs nanocomposites with more than 85% yield. This innovative idea may be expanded to other polymer systems and opens a new door to developing high performance polymer nanocomposites via green approaches and in particular, the sustainable recycling of the polymer-based materials. [ABSTRACT FROM AUTHOR]

As a part of the persistent efforts to accomplish a sustainable society, solution-hydrogen reduction was developed for preparing metal materials. Large-scale hierarchical nickel microstructures with controllable sizes and pores were constructed by adjusting the reaction conditions and the cycles of repeated reduction using nickel nanoparticles of about 700 nm as seeds and H2 as the reductant. The investigation results of the reaction conditions indicated that ammonia and nickel seeds played crucial roles in the reduction reaction. The possible formation process of self-assembled hierarchical nickel microstructures was proposed based on the results of experiments and analysis. The magnetic hysteresis loops show that the magnetic properties of nickel microstructures were also controllable by controlling the cycles. The hydrogen storage indicates that the hierarchical nickel microstructures have better hydrogen storage performance at 298 K, which may be ascribed reasonably to the H2 molecules that were adsorbed onto the surface of nickel particles and formed activated hydrogen (Ni–H). Such a cost-effective and environmentally friendly procedure is a versatile approach that may be extended to the mass production of some metals and the fabrication of some other hierarchical microstructures. [ABSTRACT FROM AUTHOR]

Magnesium batteries have emerged as one of the considerable choices for next-generation batteries. Oxide compounds have attracted great attention as cathodes for magnesium batteries because of their high output voltages and ease of synthesis. However, a majority of the reported results are based on metastable nanoscale oxide materials. This study puts forward a thermodynamically stable layer-structured oxide K 0.5 MnO 2 with an enlarged lattice spacing as a model cathode material employing optimized electrolytes, enabling Mg 2+ intercalation into the K 0.5 MnO 2 framework in a real magnesium battery directly using Mg foil as the anode. First-principles calculations implied that the enlarged layer spacing could decrease the migration energy barrier of Mg 2+ in the layered oxide. This work can pave the way to understanding the fundamental intercalation behavior of Mg 2+ in magnesium batteries., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The development of hydrogen-oxygen fuel cells with an alkaline electrolyte was highly limited by the sluggish kinetics of the hydrogen oxidation reaction (HOR). Here, with a pyrolysis-reduction route, a new RuNi-based electrocatalyst was prepared, which presents an ultrathin nanowire-like structure. In alkaline media, this catalyst shows an excellent catalytic performance with an exchange current density of 1.10 mA cm -2 disk for hydrogen oxidation. The exchange current density and mass activity of this catalyst are much higher than those of its single-metal counterparts and even the commercial Pt/C catalyst containing 20% Pt. Such a remarkable catalytic activity can be explained by the interaction between Ru and Ni; the incorporation of Ni may induce an electronic effect on the optimization of the Ru-H ad strength and provide a functional surface that can absorb OH species, thus boosting the catalytic activity. These findings may cast a new light on the exploration of low-cost but high-efficiency catalysts for fuel cells.

Resource utilization of waste plastic could solve the problem of environmental pollution and simultaneously relieve energy shortages, achieving sustainable development. In this study, the conversion of waste polytetrafluoroethylene (PTFE) to cubic silicon carbide (SiC) nanoparticles has been described. The structures and morphologies of the obtained SiC were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, the FTIR spectrum of the obtained SiC sample suggests that the waste PTFE was completely converted into SiC in our approach.