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The development of highly active and stable iron–nitrogen (Fe–Nx) based oxygen reduction reaction (ORR) catalysts with pH versatility is one of the future directions of electrochemical energy. However, the task of designing and controlling the three-dimensional local structure of Fe species to obtain high ORR activity and stability remains a challenge. In this study, we prepared hierarchical porous FeN–hcC (iron–nitrogen–highly curved carbon) catalysts derived from ZIF-L by a soft template method. The highly curved carbon surface possibly results in a compressive strain effect on the supported Fe–Nx active site, which can not only enhance the high exposure of the active site to improve the electrocatalytic activity, but also facilitate the stability of the Fe–Nx site during the ORR catalytic process. FeN–hcC-1 exhibited a high half-wave potential of 0.89, 0.77 and 0.82 V vs. RHE in alkaline, acidic, and neutral media, respectively. In addition, after cyclic durability tests in different electrolyte environments, good stability is still maintained, which is significantly better than the planar Fe–Nx site and Pt/C catalyst. This work provides a new synthetic strategy for the construction of highly curved surfaces of carbon materials, while inspiring a method to improve the ORR performance of ZIF-derived materials. [ABSTRACT FROM AUTHOR]

0.7CaTi1-x(Mg1/3Nb2/3)xO3–0.3SmAlO3 (0 ≤ x ≤ 0.04) ceramics were prepared by solid-state reaction method. The effects of (Mg1/3Nb2/3)4+ substitution on crystal structure, microstructure, and microwave dielectric properties of the ceramics were investigated. The orthorhombic perovskite structure remains unchanged, but the dielectric properties are affected significantly by replacing Ti4+ with (Mg1/3Nb2/3)4+. The dielectric constant (εr) exhibits a slight decrease from 44.9 to 43.9, and the temperature coefficient of resonance frequency (τf) exhibits a transition from + 4.1 to ‒1.4 ppm/°C with the increase of x. An appropriate amount of (Mg1/3Nb2/3)4+ substitution can promote sintering and, thus, reduce dielectric loss. The ceramic with x = 0.02 sintered at 1390 °C shows excellent microwave dielectric properties: εr = 44.1, Q × f = 45 600 GHz, and τf = + 0.8 ppm/°C. [ABSTRACT FROM AUTHOR]

Spinel-structured oxides have attracted interest owing to their long-term stability and good catalytic activity for oxygen reduction reactions. However, the insufficient rate of electron conduction in spinel-structured oxides limits their application in electrocatalysis. In this study, we propose an in situ growth of Cu–Fe spinels on the surface of N-doped glucose-derived carbon spheres via a one-pot method by adjusting the local solution environment at high temperatures, which enhances the oxygen reduction activity of the material through a tight binding between the N-doped carbon spheres and the Cu–Fe spinels. The Cu–Fe spinel material loaded on the surface of the rough porous carbon spheres showed good oxygen reduction activity with an ORR half-wave potential of 0.83 V, a transferred electron number of 3.87, a Tafel slope of 59.8 mV dec−1, a good long-term stability, and its half-wave potential remaining almost unchanged after 5000 CV tests. [ABSTRACT FROM AUTHOR]

CoFe layered double hydroxide composites (CoFe-LDH) as acetaminophen and dopamine sensing catalyst: Herein, CoFe-LDH nanosheets were prepared by ultrasonic assisted method. The stack of nanosheets was loosely arranged, providing a large contact area with the material being detected. CoFe-LDH/GCE showed excellent detection performance for dopamine and acetaminophen due to the synergistic effect of high active area and Co and Fe active sites. Moreover, it realized the detection of dopamine and acetaminophen in human serum samples. [Display omitted] • CoFe-LDH nanosheets were synthesized by ultrasonic-assisted method. • CoFe-LDH nanosheets are loosely stacked to provide a large active surface area. • CoFe-LDH nanosheets exhibit excellent properties for dopamine and acetaminophen. • CoFe-LDH realized the detection of dopamine and acetaminophen in human serum samples. Herein, CoFe layered double hydroxide composites (CoFe-LDH) were synthesised by a simple ultrasound assisted synthesis method. It has been characterized by scanning electron microscopy (SEM), X-ray diffraction and X-ray photoelectron spectroscopy. CoFe-LDH modified glass carbon electrode was used as dual-function sensors for DA and AP detection. The sensor exhibits a wide detection linear range for DA and AP (2 μM-900 μM), low detection limits (DA: 0.08 μM; AP: 0.37 μM) (S/N = 3). The sensitivity of CoFe-LDH/GCE for DA and AP were 0.54 μA μM−1 cm−2 and 0.55 μA μM−1 cm−2. And it shows good reproducibility, selectivity, and stability. In addition, the sensor demonstrated good recovery rates for the detection of DA and AP in human serum samples. [ABSTRACT FROM AUTHOR]

Engineering favorable plasmonic-based catalytically active nanostructures has been an essential part of 2,4,6-trinitrotoluene (TNT) sensing due to their synergistically enhanced catalytic performance. However, how to increase the catalytically dynamic species and improve their electrocatalytic activity is still challenging. Herein, smart plasmonic AgPtPd porous nanoparticles anchored on reduced graphene oxide (AgPtPd NPs/rGO) have been developed as a novel material for TNT detection using a wet-chemical reduction strategy in which Ag nanoparticles were used as the starting template. The smart plasmonic AgPtPd nanoparticles show a porous 3D flower-like morphology, which contribute mainly to the high-performance electrochemical detection of TNT. Meanwhile, adsorbent-assisted reduced graphene oxide with a good adsorption capacity toward TNT was introduced. When used in electrochemical TNT detection, the AgPtPd NPs/rGO exhibits a wide linear range from 0.1 to 8 ppm with a limit of detcetion (LOD) of 0.95 ppb, which is much better than the previous study. The remarkable features are probably attributed to the integrated advantages of the plasmonic properties and the synergistic effect between the smart plasmonic AgPtPd porous nanoparticles (with highly micro-reactive sites) and rGO (with good adsorption capacity toward TNT). The results show that smart plasma nanocrystals supported by rGO have broad application prospects for high-performance electrochemical sensors. [ABSTRACT FROM AUTHOR]

Developing highly effective and stable non‐precious bifunctional oxygen electrocatalysts is crucial and challenging. Herein, we report nano‐mediated straight bamboo‐shaped nitrogen‐doped carbon nanotubes modified with encapsulated NiCo2S4‐based nanoparticles (E‐NiCo2S4/SBS‐NCNTs) by electrodeposition and procedural calcination strategy, in which nitrogen‐doped carbon nanotubes with straight bamboo shape (SBS‐NCNTs) show more average diameter and encapsulated NiCo2S4‐based nanoparticles (E‐NiCo2S4) are coated by carbon, and what makes us even more excited is that they are evenly dispersed on SBS‐NCNTs surface, not just at the tip or inside. When applied for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), E‐NiCo2S4/SBS‐NCNTs show excellent catalytic activity, and onset potential (Eonset) in OER and ORR is only 1.52 V and 0.95 V (vs. RHE) in 0.1 M KOH, respectively. More importantly, the hybrids exhibit good methanol tolerance, with almost unchanged for ORR performance after adding 0.5 M methanol, and it has highly stability, the current density dropped by 22% after 7 h of reaction. The interaction of NiCo2S4 with the external carbon layer can greatly enhance the electrocatalytic activity toward the OER and it has a complete 4e– reaction process toward the ORR. The excellent electrocatalytic activity is mainly due to synergistic enhancement effect, in which SBS‐NCNTs with highly catalytic activity provide good conductivity, expose more active sites and promotes fast mass transfer; Carbon‐coated NiCo2S4‐based nanoparticles can improve the local work function of SBS‐NCNT through synergistic electronic interaction, promoting O2 adsorption, ensure rapid electron transport, and enable SBS‐NCNT to improve its electrocatalytic activity. Because of the weakness of Ostwald effect and synergistic enhancement, the stability and catalytic activity of NiCo2S4‐based nanoparticles can be greatly improved. All these advantages can synergistically improve the electrocatalytic efficiency and make it become one of the most promising bifunctional oxygen electrocatalysts. [ABSTRACT FROM AUTHOR]

In this study, the effect of Ti and Zr elements with equal mass ratio on microstructure and corrosion resistance of Zn‐11Al‐3Mg alloy was investigated. The microstructure was significantly refined and Al‐rich phase transformed from dendrite to petal‐like with the addition of Zr and Ti elements, due to the Al3(TixZr1 − x) phase as the nucleation substrate. The corrosion resistance of Zn‐11Al‐3Mg‐x(Ti,Zr) alloy was effectively improved. Moreover, the corrosion products of Zn‐Al‐Mg alloy were not changed by the addition of Ti and Zr, which are mainly composed of Zn5(OH)8Cl2·H2O and Zn6Al2(OH)16CO3·4H2O. [ABSTRACT FROM AUTHOR]

Electrochemical energy conversion and storage are important and coupled with a number of electrocatalytic processes. Renewable hydrogen, as a promising energy carrier, is closely related to the oxygen evolution reaction (OER). However, the OER kinetics is slow due to the slow 4e− transfer process. The low-cost transition metal-based catalysts provide broad prospects for the development of efficient and stable OER catalysts. Designing an efficient transition metal-based OER catalyst is beneficial to improve the overall efficiency of water decomposition. Here, we developed a new three-dimensional carbonized polyaniline fiber material loaded with Fe–Co oxide nanoparticle (denoted as 3D-CPF/FeCoOx-Nanoparticles) material by doping Fe to activate the catalytic activity of cobalt-based catalysts, introducing new reaction pathways and using the synergistic enhancement between metal nanoparticles and carbonized polyaniline fibers. Benefiting from the synergistic enhancement of the conductive three-dimensional carbonized polyaniline fibers and the high catalytic activity of FeCoOx nanoparticles, the 3D-CPF/FeCoOx-Nanoparticles only need a potential of 1.63 V to obtain a current density of 10 mA cm−2. Excitingly, the 3D-CPF/FeCoOx-Nanoparticles have exhibited potential applications in supercapacitors. [ABSTRACT FROM AUTHOR]

Here, we successfully synthesized N‐doped carbon nanotubes embedded with nickel‐based nanoparticles on the top (N‐CNTs/E‐NNPs) by directly procedural calcination of melamine and nickel foam at 520 °C, 540 °C and 700 °C in Ar. When applied for oxygen reduction reaction (ORR), the onset potential and half‐wave potential are 0.96 V and 0.86 V in 0.1 M KOH, comparable to that of the commercial 10 wt% Pt/C. Moreover, the hybrids possess higher stability and better methanol tolerance. Additionally, the Tafel slope of N‐CNTs/E‐NNPs is 76 mV dec−1 in 0.1 M KOH, lower than 83 mV dec−1 of the commercial 10 wt% Pt/C, demonstrating a good kinetic process. The remarkable features are mainly ascribed to synergistic enhancement effect from N‐rich doped carbon nanotubes (N‐CNTs) and embedded Ni‐based nanoparticles on the top, promoting mass and electrons transport, enhancing the activity of active sites and making it a promising highly efficient non‐precious metal ORR catalyst. [ABSTRACT FROM AUTHOR]

In this work, we propose a fluorescence method for the simultaneous detection of glutathione (GSH) and histidine (His) based on the Cu(ii)-thiamine (Cu(ii)-TH) system. It is well established that non-fluorescent thiamine (TH) can be oxidized by Cu(ii) to generate fluorescent thiochrome (TC) under alkaline conditions. The introduction of GSH and His can inhibit the oxidation of TH by Cu(ii) due to the strong affinity between Cu(ii) and GSH or His. With this strategy, the detection limit for GSH and His is 10.5 nM and 26.4 nM, respectively. The developed method shows several obvious advantages: (1) simplicity in design and operation without the utilization of fluorescent nanomaterials or probes; (2) time-saving detection process since all the detection process is completed within 15 min; (3) cost-effectiveness by using TH as the fluorescent substrate; and (4) higher sensitivity and good selectivity. Therefore, it shows great potential in biosensing fields. [ABSTRACT FROM AUTHOR]

Engineering sensitive gold-based nanostructured “ultra-microelectrode” systems have been an essential part of As(iii) sensing due to their high theoretical efficiency, high oxygen overpotential, high abundance and environmental benignity. However, it is still challenging to increase the specific active sites and enhance the electrocatalytic activity, the lack of which significantly limits the overall As(iii) sensing performance and largely prevent its utilization in ultra-trace detection of As(iii) in practical water systems. Herein, we report a detailed design of adsorbent assisted Fe oxide-based plasmonic Ag/Au hollow and porous nanoshells (Ag/Au HPNSs@FO) for electrochemical As(iii) determination and ultra-trace detection of As(iii) in practical water systems based on the integrated advantages of the plasmonic and ultra-microelectrode nanostructure. Ag nanoparticles were used merely as starting templates for the fabrication of plasmonic Ag/Au HPNSs and then, porous Fe oxide, with good adsorption capacity toward As(iii), was introduced by pyrolysis treatment of MIL-100(Fe) grown on the Ag/Au HPNSs. The remarkable features of abundant micro-reactive sites, improved electrochemical activity, and synergistic effects have vastly ensured outstanding electrocatalytical performance of the arsenic redox reaction. The wide linear range of detection is from 0.05 to 16 ppb and the detection limit (3σ) is 0.01 ppb. Moreover, Ag/Au HPNSs@FO exhibits high sensitivity (922.5 μA ppb−1) and stable detection. Most importantly, the ultra-trace detection of As(iii) in practical water systems can be achieved by Ag/Au HPNSs@FO with unprecedentedly low concentrations (ca. 1 ppt and even lower concentrations). [ABSTRACT FROM AUTHOR]

Alkaline phosphatase (ALP) is a significant biomarker for diagnostics. Simple, selective and sensitive detection of ALP activity is thus of critical importance. In this study, an artful fluorescence assay for ALP is proposed based on adenosine triphosphate (ATP) hydrolysis-triggered disassociation and fluorescence quenching of cerium coordination polymer nanoparticles (CPNs). ATP, a recognized natural substrate of phosphatase, can serve as a superb “antenna” to sensitize the luminescence of Ce3+ with the aid of tris(hydroxymethyl) aminomethane (Tris), forming Ce3+–ATP–Tris CPNs. In the presence of ALP, ATP will be catalytically converted into adenosine and inorganic orthophosphate, however neither of them can sensitize Ce3+ in alkaline media. As a result, the obtained CPNs are disassociated, inducing the quenching of the fluorescence. On this basis, a straightforward fluorescence assay for ALP activity is rationally developed. The fluorescence quenching efficiency shows a linear relationship for ALP within the activity range from 0.1 to 10 mU mL−1 with a detection limit of 0.09 mU mL−1 under the optimal experimental conditions. Moreover, this facile yet effective fluorescence method featured simplicity, cost-effectiveness, high sensitivity and high selectivity and can be successfully utilized for the quantitative detection of ALP in human serum samples. [ABSTRACT FROM AUTHOR]

Abstract: Plasmonic bimetallic structures have been wildly used in photocatalysis, owing to their tunable optical properties and desirable catalytic activities. However, it is still a challenge to realize the enhanced electrocatalytic hydrogen evolution reaction (HER) using these structures with electric, photo‐, and thermal effects. Herein, we report that Pd‐tipped Au nanorods (NRs) were prepared for electrochemical water splitting in the visible and near‐infrared region. The NRs exhibited a lower onset overpotential (40 mV) and high exchange current density (1.585 mA/cm2), which was largely ascribed to the increased carrier density in Pd induced by photo‐excited Au NRs, and further enhancement of Pd catalytic activity resulted from the photothermal effect of Au NRs. As the hot electron transport channel was hindered by excess Pd nanoparticles, it was found that the HER performance of tipped NRs was much higher than that of fully covered ones. This study extends enhanced electrocatalytic HER activity with plasmonic bimetallic structures by taking full advantage of the synergy between photoelectric and photothermal effects. [ABSTRACT FROM AUTHOR]

Gold nanorods (GNRs) with suitable aspect ratios have strong localized surface plasmon resonance (LSPR) absorption and scattering in the 650–900 nm near-infrared region, which make them attractive for in vitro or in vivo imaging and photothermal cancer therapy. However, they often suffer from cytotoxicity and instability for practical applications, and therefore need further surface modification to solve these issues. In this study, GNRs coated with biocompatible polyaniline (PANI) were used as a stable and highly efficient photothermal agent for cancer cell ablation. Fine-tuning the LSPR response of the GNR–PANI core–shell nanoparticles via thickness-controlled coating of the PANI nanoshells, optimizes the photothermal conversion efficiency of the agent. As a result of the contributions from the GNR core and PANI shell, the capability of photothermal transduction of the resultant nanoparticles at 808 nm is greatly enhanced. After exposure to a continuous NIR laser at 808 nm for ∼5 min, cancer cells were efficiently ablated requiring only a very low laser flux of 0.6 W cm−2, the lowest value reported to date for plasmonic nanostructures, showing the great potential for photothermal cancer therapy. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) is coupled with a number of important cathodic processes, for instance water splitting for hydrogen production and other energy storage devices based on O2–H2O chemistries such as metal–air batteries and unitized regenerative fuel cells, but they are limited by the slow kinetics. Attempts to solve this problem have received wide attention recently. However, accessing and stabilizing high-oxidation-state catalytically active species to further improve the high performance for the OER has been considered a huge challenge. Here, we report a Ni–Fe oxide-based nanotube array electrode, novel in design, with strong durability and excellent and synergistically enhanced catalytic performance for the OER. The OER electrode, with a nanotube array nanostructure, shows the remarkable features of a small overpotential of 0.28 V, favourable electrode kinetics and high stability, comparing favorably with the reported performances of the best OER electrocatalysts (IrO2), which is attributed to the formation and stabilization of the favourable OER catalytically active species NiOOH that is produced and reinforced by the introduction of Fe into nanostructured materials. This feasible strategy affords a new strategy for the development of effective and robust OER electrodes. [ABSTRACT FROM AUTHOR]

Developing nanostructured Ni and Co oxides with a small overpotential and fast kinetics of the oxygen evolution reaction (OER) have drawn considerable attention recently because their theoretically high efficiency, high abundance, low cost, and environmental benignity in comparison with precious metal oxides, such as RuO2 and IrO2. However, how to increase the specific activity area and improve their poor intrinsic conductivity is still challenging, which significantly limits the overall OER rate and largely prevent their utilization. Thus, developing effective OER electrocatalysts with abundant active sites and high electrical conductivity still remains urgent. In this work, a scrupulous design of OER electrode with a unique sandwich-like coaxial structure of the three-dimensional Ni@[Ni(2+/3+)Co2(OH)6-7] x nanotube arrays (3D NNCNTAs) is reported. A Ni nanotube array with open end is homogeneous coated with Ni and Co co-hydroxide nanosheets ([Ni(2+/3+)Co2(OH)6-7] x) and is employed as multifunctional interlayer to provide a large surface area and fast electron transport and support the outermost [Ni(2+/3+)Co2(OH)6-7] x layer. The remarkable features of high surface area, enhanced electron transport, and synergistic effects have greatly assured excellent OER activity with a small overpotential of 0.46 V at the current density of 10 mA cm−2 and high stability. [ABSTRACT FROM AUTHOR]

In diluted solid solution using poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and polymethyl methacrylate (PMMA) or polystyrene (PS), both aggregated and extended conformations could be formed according to the weight ratio. Aggregated conformation in as-cast MEH-PPV/PMMA film presented a J-aggregate-like photoluminescence (PL) emission. After annealing at 160 °C, its PL showed characteristics of both J- and H-aggregates at the same time; however, extended conformation showed an oligomer-like emission, which was not sensitive to either measurement temperature or annealing temperature. Thus, the conformation transition between aggregated and extended is unlikely to happen in MEH-PPV/PMMA blends during thermal annealing. On the contrary, in MEH-PPV/PS blends, extended conformation dominated in as-cast film with oligomer-like emissions; after annealing at 160 °C, both J- and H- aggregate-like PL emissions were observed, indicating the conformation transitioned from extended to aggregated. Therefore, our work may suggest a new method to manipulate photophysical properties of conjugated polymers by combining appropriate host matrix and thermal annealing processes. [ABSTRACT FROM AUTHOR]

3D HPN-GCNS/Co@CoO x as catalysts for ORR: The hybrids were fabricated by a controllable grading-pyrolysis strategy. The hybrids show 3D fluffy and hierarchically porous nanostructure in and out-of-plane, resulting in large accessible specific activity area, allowing the species to efficiently participate in ORR and facilitating the fast mass transfer; the graphene-like C nanosheets with N-rich dopant promote O 2 adsorption and assure fast electron transport; large numbers of Co@CoO x -based nanoparticles uniformly embedded on the C nanosheets and mesoporous active edge introduce more ORR active sites. The remarkable features synergistically enhance the ORR catalytic efficiency, making it a promising low-cost, highly efficient ORR catalyst. • The hybrids were successfully fabricated by a controllable grading pyrolysis strategy. • Graphene-like C nanosheets with N-rich dopant show in and out-of-plane nanostructure. • Co-based nanoparticles uniformly embedded on fluffy and hierarchically C nanosheets. • The remarkable features synergistically enhance the ORR catalytic efficiency. Here, Co@CoO x -based three-dimensional nitrogen-doped graphene-like carbon nanosheets (denoted as 3D HPN-GCNS/Co@CoO x) are fabricated by controllable grading-pyrolysis strategy, in which they show 3D fluffy and hierarchically porous nanostructure in and out-of-plane; large numbers of Co@CoO x -based nanoparticles uniformly embedded on graphene-like C nanosheets and mesoporous active edge introduce more ORR active sites. When applied for ORR, hybrids exhibit a half-wave potential (E 1/2) of 0.87 V and an onset potential (E onset) of 0.92 V in 0.1 M KOH, comparable to that of commercial 20% Pt/C. The hybrids display better methanol tolerance and stability, with almost no change of ORR performance before and after 5000 cycles. H 2 O 2 yield in ORR process is less than 5% and number of electron transfer is higher than 3.9. The remarkable features are mainly ascribed to synergistic enhancement effect, in which 3D fluffy and hierarchically porous nanostructure in and out-of-plane supplies large accessible specific activity area, allows species to efficiently participate in ORR and facilitates fast mass transfer; graphene-like C nanosheets with N-rich dopant promote O 2 adsorption and assure fast electron transport; large numbers of Co@CoO x -based nanoparticles introduce more ORR active sites. All the advantages synergistically enhance the ORR efficiency and make it a highly efficient ORR catalyst. [ABSTRACT FROM AUTHOR]

The authors have fabricated reduced graphene oxide nanosheets (rGO) supported with Fe3O4 nanoparticles and Ag/Au hollow nanoshells. The material was placed on a glassy carbon electrode which is shown to enable highly sensitive determination of As(III) which is first preconcentrated from solution at a potential of −0.35 V (versus Ag/AgCl) for 100 s. The electrode, typically operated at a working potential as low as 0.06 V, has a linear response in the 0.1 to 20 ppb As(III) concentration range and a 0.01 ppb detection limit. The electrochemical sensitivity is 52 μA ppb−1. The high sensitivity is assumed to be the result of various synergistic effects. The method was applied to ultratrace (0.1 ppt) determination of As(III) in real water samples. Graphical abstract The hybrid displays a wide linear response in the 0.1 to 20 ppb As(III) concentration range and a 0.01 ppb detection limit. The high sensitivity is attributed to various synergistic effects. The method was applied to ultratrace determination of As(III) in real water samples. [ABSTRACT FROM AUTHOR]

Abstract: The project of a 14MeV PET cyclotron aiming at medical diagnosis and treatment was proposed and started at CIAE in 2010. The low-level RF system is designed to stabilize acceleration voltage and control the resonance of the cavity. Based on the experience of the existing CRM Cyclotron in CIAE, a new start-up sequence is developed and tested. The frequency sweeping is used to activate the RF system. Before the tuner is put into use, a new state called “DDS tuning” is applied to trace the resonance frequency to the designed value. This new option state helps to cover the tuning range, if a large frequency variation occurs because of a thermal cavity deformation. The logic control unit detects the spark, reflection, Pulse/CW state and the frequency of the RF source to perform all kinds of protection and state operations. The test bench and on-line test are carried out to verify the initial design. [Copyright &y& Elsevier]