Anthraquinone/activated carbon electrochemical sensor and its application in acetaminophen analysis.

Acetaminophen (AC) can inhibit the synthesis of prostaglandins in the body, and has antipyretic and analgesic effects. In this paper, a two-step microwave impregnation method was used to prepare anthraquinone (AQ)-doped carbon composite, which were applied to the surface modification of glassy carbon electrodes (GCE) for the determination of acetaminophen (AC) using differential pulse voltammetry (DPV). The composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman and Fourier infrared spectroscopy (FT-IR). The results showed that anthraquinone was successfully modified on the surface of activated carbon. The peak current of AC increased with its concentration in the range of 0.1 µM to 700 µM (R2 = 0.998) and a detection limit of 0.05 µM was obtained with 20%AQ doped carbon electrochemical sensor (20%AQ-C/GCE). Electrochemical Impedance Spectroscopy (EIS) test results indicated that the charge transfer resistance (Rct) of 20%AQ-C/GCE is only the one-fourth of that of bare GCE. The proposed 20%AQ-C/GCE sensor has good stability, reproducibility and selectivity for the detection of AC. The sensor is also suitable for the detection of real samples, indicating its good practicality.

Surface N Sites Mediate the Formation of Li Metal Cluster@N-Enriched Hierarchically Porous Carbon for Ultrahigh-Capacity Lithium Storage.

Graphite is the popular anode material of current lithium-ion batteries (LIBs). However, its low specific capacity and poor lithium intercalation potential hinder its use for high-power and large-scale energy storage. To meet the demand for energy storage, novel anode materials with high capacity, fast chargeable capability, and long cycle life are of great interest. Herein, we demonstrate an advanced nitrogen-enriched hierarchical porous carbon serving as a lithiophilic anode material for ultrahigh capacity and long-life LIBs. NHPC-700 (under optimal synthetic conditions), featuring a high surface area, rich N-doping, high porosity, and partially graphitized nanosheet structures, is successfully fabricated from a Schiff-base copolymer via a template-incipient wetness impregnation method. NHPC-700 exhibits an ultrahigh reversible lithium storage capacity of 2796 mA h g-1 at 0.1 A g-1 while still maintaining a high capacity of 526 mA h g-1 at 10 A g-1 after 1000 cycles. Theoretical and experimental studies reveal that this remarkable Li storage performance can be attributed to the large number of N lithiophilic sites on the inner surface of the small mesoporous pores. These sites guide Li metal nucleation in the initial period and control well the volume variation during charge/discharge cycles, thus exhibiting excellent cycle stability and great potential for practical application.

Employing hybrid deep learning for near-real-time forecasts of sensor-based algal parameters in a Microcystis bloom-dominated lake.

Harmful cyanobacterial blooms (CyanoHABs) are increasingly impacting the ecosystem of lakes, reservoirs and estuaries globally. The integration of real-time monitoring and deep learning technology has opened up new horizons for early warnings of CyanoHABs. However, unlike traditional methods such as pigment quantification or microscopy counting, the high-frequency data from in-situ fluorometric sensors display unpredictable fluctuations and variability, posing a challenge for predictive models to discern underlying trends within the time-series sequence. This study introduces a hybrid framework for near-real-time CyanoHABs predictions in a cyanobacterium Microcystis-dominated lake - Lake Dianchi, China. The proposed model was validated using hourly Chlorophyll-a (Chl a) concentrations and algal cell densities. Our results demonstrate that applying decomposition-based singular spectrum analysis (SSA) significantly enhances the prediction accuracy of subsequent CyanoHABs models, particularly in the case of temporal convolutional network (TCN). Comparative experiments revealed that the SSA-TCN model outperforms other SSA-based deep learning models for predicting Chl a (R2 = 0.45-0.93, RMSE = 2.29-5.89 µg/L) and algal cell density (R2 = 0.63-0.89, RMSE = 9489.39-16,015.37 cells/mL) at one to four steps ahead predictions. The forecast of bloom intensities achieved a remarkable accuracy of 98.56 % and an average precision rate of 94.04 % ± 0.05 %. In addition, scenarios involving various input combinations of environmental factors demonstrated that water temperature emerged as the most effective driver for CyanoHABs predictions, with a mean RMSE of 2.94 ± 0.12 µg/L, MAE of 1.55 ± 0.09 µg/L, and R2 of 0.83 ± 0.01. Overall, the newly developed approach underscores the potential of a well-designed hybrid deep-learning framework for accurately predicting sensor-based algal parameters. It offers novel perspectives for managing CyanoHABs through online monitoring and artificial intelligence in aquatic ecosystems.

Oxygen defect-mediated NiCo2O4 nanosheets as the electrode for pseudocapacitors with improved rate capability.

Transition metal oxide-based supercapacitors have attracted much attention due to their high theoretical specific capacitances. However, due to an insufficient utilization ratio and poor intrinsic conductivity of active materials, the rate performance of these electrodes is usually low. Herein, oxygen defect-mediated NiCo2O4 nanosheets with enhanced electrical conductivity (1.9 S m-1vs. 0.2 S m-1 of original NiCo2O4 NSs) are fabricated using a post NaBH4 reduction strategy (denoted as r-NiCo2O4 NSs). The derived r-NiCo2O4 materials have sheet-like morphology, increased oxygen defects and low valence metal species, and an unprecedented rate capability comparable to that of carbon-based electrode materials, with a satisfactory capacitance of 1812 F g-1 and 91.5% retention at 20 A g-1. The general strategy can be extended to other transition metal oxides to construct enhanced conductivity electrodes for related energy storage and conversion devices.

In-situ electrodeposited Co0.85Se@Ni3S2 heterojunction with enhanced performance for supercapacitors.

Rational design of porous heterostructured electrode materials for high-performance supercapacitors remains a big challenge. Herein, we report the in situ synthesis of Co0.85Se@Ni3S2 hybrid nanosheet arrays supported on carbon cloth (CC) substrate though an efficient two-step electrodeposition method. Compared with pure Co0.85Se and Ni3S2, the well-defined Co0.85Se@Ni3S2 heterojunction possesses enriched active sites, improved electrical conductivity, and reduced ion diffusion resistance. Benefiting from its hierarchically porous nanostructure and the synergistic effect of Co0.85Se and Ni3S2, the as-synthesized Co0.85Se@Ni3S2 electrode delivers a gravimetric capacitance (Cg)/volumetric capacitance (Cv) of 1644.1F g-1/3161.7F cm-3 at 1 A g-1, outstanding rate capability of 60.7% capacitance retention at 20 A g-1, as well as good cycling performance of 87.8% capacitance retention after 5000 cycles. Additionally, a hybrid supercapacitor (HSC) device presents a maximum energy density (E) of 65.7 Wh kg-1 at 696.2 W kg-1 with 93.3% cyclic durability after 15,000 cycles. Thus, this work proposes a simple and effective strategy to fabricate porous heterojunctions as high-performance electrode materials for energy storage devices.

Constructing nickel sulfide @ nickel boride hybrid nanosheet arrays with crystalline/amorphous interfaces for supercapacitors.

Designing a heterostructure with unique morphology and nanoarchitecture is regarded as an efficient strategy to achieve high-energy-density supercapacitors (SCs). Herein, a rational nickel sulfide @ nickel boride (Ni9S8@Ni2B) heterostructure is in situ synthesized on carbon cloth (CC) substrate via a simple electrodepositon strategy followed by a chemical reduction method. The three-dimensional hierarchically porous Ni9S8@Ni2B nanosheet arrays, consisting of crystalline Ni9S8 nanosheets and amorphous Ni2B nanosheets, can expose ample electroactive centers, shorten ion diffusion distance, and buffer volume changes during charging/discharging process. More importantly, the generation of crystalline/amorphous interfaces in the Ni9S8@Ni2B composite modulates its electrical structure and improves electrical conductivity. Owing to the synergy of Ni9S8 and Ni2B, the as-synthesized Ni9S8@Ni2B electrode acquires a specific capacity of 901.2C g-1 at 1 A g-1, a sound rate capability (68.3% at 20 A g-1), along with good cycling performance (79.7% capacity retention over 5000 cycles). Additionally, the assembled Ni9S8@Ni2B//porous carbon asymmetric supercapacitor (ASC) exhibits a cell voltage of 1.6 V and a maximum energy density of 59.7 Wh kg-1 at 805.2 W kg-1. These findings might offer a simple and innovative approach to fabricate advanced electrode materials for high-performance energy storage systems.

Structurally-stable Mg-Co-Ni LDH grown on reduced graphene by ball-milling and ion-exchange for highly-stable asymmetric supercapacitor.

As an electrode for energy storage, the inherently poor conductivity of metal hydroxides (MHs) can be improved by in situ growth of MHs on conductive carbon based substrates so that their performances on energy storage could be enhanced to a high level. However, the incompatibility of hydrophilic component (metal hydroxides) and hydrophobic counterpart (carbon based materials) makes it difficult to be accomplished. Herein, we presented a scalable and easy-operated strategy by ball-milling combined with ion-exchange technique to grow Mg-Co-Ni LDH (layered double hydroxides) on reduced graphene, in which ball-milling was utilized to disperse the staring material of magnesium acetate on graphene oxide (GO) to obtain the composite of Mg(Ac)2/GO. The composite can be in situ transformed to MgO/reduced grapheme (rG) by following heat treatment. While, the ion-exchange reaction could enables the in situ growth of Mg-Co-Ni LDHs on the reduced graphene. The derived products (denoted as Mg-Co-Ni LDH/rG-x) owns nanosheet morphology, surface area of 59-115 m2/g, homogenous elements distribution. As electrode for supercapacitor, the maximum capacitance of 1204F/g@1.0 A/g was achieved and the corresponding asymmetric supercapacitor device shows a large energy density of 44.3 Wh/kg@800 W/kg. Particularly, a superlong cycling stability with 90.5% capacitance retention of the first cycle was attained after continuous charge/discharge for 20 000 cycles at current density of 5.0 A/g, promising great potential for practical energy storage application. The present strategy is simple and scalable that can be widely applied to the synthesis of various hydroxides/oxides or multi-component hydroxides/oxides on carbon substrates forming a composite structure, thus offers a great potential for broad application areas including catalysis, adsorption, energy storage, etc.

Mushroom-like cobalt nickle metaphosphate@nickel diselenide core-shell nanorods for asymmetric supercapacitors.

Although transition metal metaphosphates (TMPOs) display special physical/chemical features and high theoretical capacities, their applications for supercapacitors (SCs) are still restricted by their low energy densities and inferior cycling stability. Herein, a novel strategy has been proposed to address these issues through in situ construction of cobalt nickle metaphosphate (Co0.2Ni0.8(PO3)2)@nickel diselenide (NiSe2) core-shell heterostructure on carbon paper (CP) as a self-supporting flexible electrode for SCs. Particularly, this unique mushroom-like porous nanoarchitecture assembled by one-dimensional (1D) Co0.2Ni0.8(PO3)2 nanorods and zero-dimensional (0D) NiSe2 nanospheres can expose abundant active sites and afford multi-dimensional channels, which favors rapid electron ions/electron transfer, accelerates the reaction kinetics, and alleviates volume changes during charging/discharging processes. Profiting from its well-aligned 1D/0D nanostructure and strong synergistic effect between Co0.2Ni0.8(PO3)2 and NiSe2, the Co0.2Ni0.8(PO3)2@NiSe2/CP electrode delivers a specific capacity of 219.4 mAh/g/0.414 mAh cm-2 at 1 A/g and good cycling stability with capacity retention of 90.7% after 5000 cycles, outperforming many previously reported TMPO-based electrodes in literature. Impressively, an asymmetric supercapacitor (ASC) device assembled with Co0.2Ni0.8(PO3)2@NiSe2 as cathode and porous carbon as anode achieves an energy density of 69.2 Wh kg-1 at 736.0 W kg-1 and maintains a capacity retention of 97.6% after 20,000 charge-discharge cycles. This work provides an efficient approach to design multi-dimensional hybrid nanomaterials for high-performance SCs.

Superbases-templated carbons doped with electrochemically active oxygen as advanced supercapacitor electrodes.

Templating techniques have been widely adopted for the synthesis of porous carbons, such as oxygen-doped porous carbon nanosheets (O-PCNs), but the effect of the surface characteristics of templates on the surface functionality and performance of a derived carbon has not been well studied. Herein, a series of laboratory-made superbases of K/Mg(OH)2 with different K/Mg ratios were employed as template to fabricate nanocarbon materials. The aim is to find out how the strength of template basicity could influence the surface functionalities and the supercapacitor performances of the derived O-PCNs. The resulting materials are rich in conjugated hydroxyl and carbonyl groups that are electrochemically active owing to the protection of the conjugated hydroxyl group by KOH and the dehydrogenation step catalyzed by magnesium oxide. Systematic investigations revealed that with the increase of basic strength, the content of the derived electrochemically active oxygen species in the forms of conjugated carbonyl (CO) and hydroxyl (COH) first increases from 8.4 atom% to 11.4 atom% then decreases to 9.25 atom%. Moreover, the microporosity of the O-PCNs stepwise increases with the rise of KOH loading, ascribable to the effect of KOH etching on the carbon skeleton. The O-PCN-20 templated by 20 % K/Mg(OH)2 is rich in porosity, large in surface area (930 m2/g) and high in active oxygen content (11.4 atom%). With high active surface area and extra Faradaic capacitance, O-PCN-20 exhibited superior supercapacitor performances including large specific capacitance of 375 F/g@1.0 A/g, high rate capability of 81.1 % (from 1.0 A/g to 20 A/g), energy density of 25.7 Wh/kg@900 W/kg and excellent cycling stability with near 100 % capacitance retentions after 10 000 cycles and more than 86.2 % capacitance retention over 20 000 cycles at large current density of 10 A/g, indicating O-PCN-20 has potential to be used as electrode material for energy storage devices.

1D-on-1D core-shell cobalt iron selenide @ cobalt nickel carbonate hydroxide hybrid nanowire arrays as advanced battery-type supercapacitor electrode.

Sluggish kinetics and poor structural stability are two main obstacles hampering the exploration of transition metal selenides (TMSs) for supercapacitor. Developing a reasonable core-shell heterostructure with unique morphology is an effective approach to resolve these issues. Herein, a core-shell cobalt iron selenide (CoFe2Se4) @ cobalt nickel carbonate hydroxide (CoNi-CH) heterostructure is directly fabricated on carbon cloth via an electrodeposition method followed by a hydrothermal reaction. In this well-defined heterostructure, one-dimensional (1D) CoFe2Se4 nanowires function as the cores and CoNi-CH nanowires as the shells, which combines the merits of highly conductive CoFe2Se4 for rapid electron transfer and highly electroactive CoNi-CH for multiple redox reactions. Further, the intimate interaction between CoNi-CH and CoFe2Se4 realizes large surface area with hierarchical network and generates rich heterointerfaces with modified the electronic structure. By virtue of its facile 1D-on-1D nanoarchitecture and synergistic effect, the CoFe2Se4@CoNi-CH electrode delivers a increased specific capacity of 218.6 mAh g-1 at 1 A-1 and enhanced rate capability (65.5% at 20 A g-1) compared with pure CoFe2Se4 and CoNi-CH. Besides, a hybrid supercapacitor is established by coupling CoFe2Se4@CoNi-CH cathode and porous carbon anode, which enjoys a maximum energy density of 67.3 Wh kg-1 at 765.9 W kg-1 and prominent durability with 85.4% of capacity retention over 20,000 cycles.

Nickel cobalt sulfide coated iron nickel selenide hierarchical nanosheet arrays toward high-performance supercapacitors.

Tailoring the electronic structure of nanomaterials by constructing core-shell heterostruture is a compelling strategy to design novel electrode materials with modified physiochemical properties for supercapacitors with improved performance. Herein, for the first time, we in situ fabricate iron nickel selenide (FeNiSe2)@nickel cobalt sulfide (Ni4.5Co4.5S8) core-shell nanosheet arrays on carbon cloth by an electrodeposition approach and a selenization treatment. This three-dimensional hierarchcial porous framework formed by plentiful interconnected nanosheets can expose numerous redox active sites with varied oxidation states and provide a conductive and porous skeleton for rapid ion/electrolyte ions transport. Benefiting from its modulated electronic structure and synergetic effect of metal-like FeNiSe2 and Ni4.5Co4.5S8, the as-synthesized FeNiSe2@Ni4.5Co4.5S8 electrode displays a large specific capacity of 236.9 mAh g-1 at 1 A g-1, remarkable rate capability with 80.6% capacity retention at 20 A g-1, and stable cyclic performance, which are superior to those of pure FeNiSe2 and Ni4.5Co4.5S8 electrodes. Besides, the assembled FeNiSe2@Ni4.5Co4.5S8//porous carbon hybrid supercapacitor device offers an energy density of 69.0 Wh kg-1 at 799.2 W kg-1, and exceptional cycling stability with 91.2% capacity retention after 10,000 cycles. This work offers a synthetic strategy to explore core-shell electrode materials with tunable architecture and morphology for high-performance energy storage devices.

A Crack Propagation Method for Pipelines with Interacting Corrosion and Crack Defects.

Corrosion and crack defects often exist at the same time in pipelines. The interaction impact between these defects could potentially affect the growth of the fatigue crack. In this paper, a crack propagation method is proposed for pipelines with interacting corrosion and crack defects. The finite element models are built to obtain the Stress Intensity Factors (SIFs) for fatigue crack. SIF interaction impact ratio is introduced to describe the interaction effect of corrosion on fatigue crack. Two approaches based on extreme gradient boosting (XGBoost) are proposed in this paper to predict the SIF interaction impact ratio at the deepest point of the crack defect for pipelines with interacting corrosion and crack defects. Crack size, corrosion size and the axial distance between these two defects are the factors that have an impact on the growth of the fatigue crack, and so they are considered as the input of XGBoost models. Based on the synthetic samples from finite element modeling, it has been proved that the proposed approaches can effectively predict the SIF interaction impact ratio with relatively high accuracy. The crack propagation models are built based on the proposed XGBoost models, Paris' law and corrosion growth model. Sensitivity analyses regarding corrosion initial depth and axial distance between defects are performed. The proposed method can support pipeline integrity management by linking the crack propagation model with corrosion size, crack size and the axial distance. The problem of how the interaction between corrosion and crack defects impacts crack defect growth is investigated.

Design of mesoporous Ni-Co hydroxides nanosheets stabilized by BO2- for pseudocapacitors with superior performance.

The investigation of high-efficiency electrodes is essential for the energy conversion/storage devices. In this work, mesoporous two-dimensional Ni-Co hydroxide nanosheets stabilized by BO2- (denoted as (NixCoy)(OH)2/Co(BO2)2) are prepared via a facile and cost-effective procedure to circumvent the shortage of nickel hydroxide, viz. poor conductivity and fast phase transition. The (NixCoy)(OH)2/Co(BO2)2 materials have high specific surface area and plenty of exposed active sites. As electrode, the optimized (Ni0.5Co0.5)(OH)2/Co(BO2)2 delivers a remarkable specific capacity of 2257 F g-1 at 1 A g-1 with superior rate capability (2071 F g-1 at 20 A g-1). Moreover, the asymmetric supercapacitors assembled by (Ni0.5Co0.5)(OH)2/Co(BO2)2 and active carbon provides high energy density (56.5 Wh kg-1 at 0.8 kW kg-1) and excellent cyclic stability (maintaining 98% of initial capacity over 10 000 cycles), demonstrating the promising potential of (Ni0.5Co0.5)(OH)2/Co(BO2)2 in practical applications.

NiAlP@Cobalt substituted nickel carbonate hydroxide heterostructure engineered for enhanced supercapacitor performance.

Transitional metal phosphides with high electrical conductivity and superb physicochemical features have been recognized as ideal battery-type electrode materials for outstanding performance supercapacitors. However, their specific capacities and structural stability are needed to be enhanced for large-scale practical applications. To overcome these shortcomings, we fabricated heterostructured NiAlP@cobalt substituted nickel carbonate hydroxide (Co-NiCH) nanosheet arrays by sequential a hydrothermal reaction, a phosphorization treatment, and a second hydrothermal reaction. Profiting from its core-shell porous nanostructure and synergistic effect of NiAlP with high electrical conductivity and Co-NiCH with high redox reactivity, the resultant NiAlP@Co-NiCH electrode delivers a large specific capacity of 825.7C g-1 at 1 A g-1, excellent rate capability with 78.9% capacity retention and long lifespan, superior to those of pure NiAlP and Co-NiCH electrodes. Additionally, an aqueous asymmetric supercapacitor device is constructed by NiAlP@Co-NiCH and lotus pollen-derived hierarchical porous carbon, which demonstrates a large energy density of 82.3 Wh kg-1 at a power density of 739.8 W kg-1, and wonderful cycle stability with 88.2% capacity retention after 10,000 cycles. This work proposes a feasible strategy on construction of transitional metal phosphide-based heterojunctions for advanced asymmetric supercapacitor devices.

Freestanding trimetallic Fe-Co-Ni phosphide nanosheet arrays as an advanced electrode for high-performance asymmetric supercapacitors.

Transition metal phosphides hold great promise for high performance battery-type electrode materials due to their superb electrical conductivity and high theoretical capacity. Unfortunately, the electrochemical properties of single metal or bimetallic phosphides are unsatisfactory owing to their low energy density and poor cyclic stability, and one feasible approach is to introduce heteroatoms to form trimetallic phosphides. Here, novel Fe-Co-Ni-P nanosheet arrays are in situ synthesized on a flexible carbon cloth substrate via an electrodeposition method followed by a phosphorization treatment. Due to the presence of abundant redox active sites, large specific surface area with mesoporous channels, desirable electrical conductivity, modified electronic structure, and synergistic effect of Fe, Co, and Ni ions, the as-prepared Fe-Co-Ni-P electrode displays significantly enhanced electrochemical performance when compared to bimetallic phosphides Fe-Co-P and Fe-Ni-P. Remarkably, the Fe-Co-Ni-P electrode exhibits a large specific capacity of 593.0 C g-1 at 1 A g-1, exceptional rate performance (80.3% capacity retention at 20 A g-1), and good cycling stability (84.2% capacity retention after 5000cycles). Besides, an asymmetric supercapacitor device with Fe-Co-Ni-P electrode as a positive electrode and a hierarchical porous carbon as a negative electrode shows a high energy density of 57.1 Wh kg-1 at a power density of 768.5 W kg-1 as well as excellent cyclability with 88.4% of initial capacity after 10,000cycles. This work manifests that the construction of trimetallic phosphides is an effective strategy to solve the shortcomings of single or bimetallic phosphides for high-performance supercapacitors.

A Prognostics Method Based on Back Propagation Neural Network for Corroded Pipelines.

A method that employs the back propagation (BP) neural network is used to predict the growth of corrosion defect in pipelines. This method considers more diversified parameters that affect the pipeline's corrosion rate, including pipe parameters, service life, corrosion type, corrosion location, corrosion direction, and corrosion amount in a three-dimensional direction. The initial corrosion time is also considered, and, on this basis, the uncertainties of the initial corrosion time and the corrosion size are added to the BP neural network model. In this paper, three kinds of pipeline corrosion growth models are constructed: the traditional corrosion model, the corrosion model considering the uncertainties of initial corrosion time and corrosion depth, and corrosion model also considering the uncertainties of corrosion size (length, width, depth). The rationality and effectiveness of the proposed prediction models are verified by three case studies: the uniform model, the exponential model, and the gamma process model. The proposed models can be widely used in the prediction and management of pipeline corrosion.

Rational synthesis of CoFeP@nickel-manganese sulfide core-shell nanoarrays for hybrid supercapacitors.

Transition metal phosphide electrodes, particularly those with unique morphologies and micro-/nanostructures, have demonstrated desirable capabilities for hybrid supercapacitor applications by virtue of their superior electrical conductivity and high electrochemical activity. Here, three-dimensional hierarchical CoFeP@nickel-manganese sulfide nanoarrays were in situ constructed on a flexible carbon cloth via a hydrothermal method, a phosphorization process, followed by an electrodeposition approach. In this smart nanoarchitecture, CoFeP nanorods grown on carbon cloth act as the conductive core for rapid electron transfer, while the nickel-manganese sulfide nanosheets decorated on the surface of CoFeP serve as the shell for efficient ion diffusion, forming a stable core-shell heterostructure with enhanced electrical conductivity. Benefiting from the synergy of the two components and the generation of a heterointerface with a modified electronic structure, The CoFeP@nickel-manganese sulfide electrodes deliver a high capacity of 260.7 mA h g-1 at 1 A g-1, excellent rate capability, and good cycling stability. More importantly, an aqueous hybrid supercapacitor based on CoFeP@nickel-manganese sulfide as a positive electrode and a lotus pollen-derived hierarchical porous carbon as a negative electrode is constructed to display a maximum energy density of 60.1 W h kg-1 at 371.8 W kg-1 and a good cycling stability of 85.7% capacitance retention after 10 000 cycles.

Surrounded catalysts prepared by ion-exchange inverse loading.

The supported catalyst featuring highly dispersed active phase on support is the most important kind of industrial catalyst. Extensive research has demonstrated the critical role (in catalysis) of the interfacial interaction/perimeter sites between the active phase and support. However, the supported catalyst prepared by traditional methods generally presents low interface density because of limit contact area. Here, an ion-exchange inverse loading (IEIL) method has been developed, in which the precursor of support is controllably deposited onto the precursor of active phase by ion-exchange reaction, leading to an active core surrounded (by support) catalyst with various structures. The unique surrounded structure presents not only high interface density and mutually changed interface but also high stability due to the physical isolation of active phase, revealing superior catalytic performances to the traditional supported catalysts, suggesting the great potential of this new surrounded catalyst as the upgrade of supported catalyst in heterogeneous catalysis.

The promoted catalytic hydrogenation performance of bimetallic Ni-Co-B noncrystalline alloy nanotubes.

A noncrystalline Ni-B alloy in the shape of nanotubes has demonstrated its superior catalytic performance for some hydrogenation reactions. Remarkable synergistic effects have been observed in many reactions when bimetallic catalysts were used; however, bimetallic noncrystalline alloy nanotubes are far less investigated. Here, we report a simple acetone-assisted lamellar liquid crystal approach for synthesizing a series of bimetallic Ni-Co-B nanotubes and investigate their catalytic performances. The dilution effect of acetone on liquid crystals was characterized by small-angle X-ray diffraction (SAXRD) and scanning electron microscopy (SEM). The Ni/Co molar ratio of the catalyst was varied to study the composition, porous structure, electronic interaction, and catalytic efficiency. In the liquid-phase hydrogenation of p-chloronitrobenzene, the as-prepared noncrystalline alloy Ni-Co-B nanotubes exhibited higher catalytic activity and increased stability as compared to Ni-B and Co-B alloy nanotubes due to electronic interactions between the nickel and cobalt. The excellent hydrogenation performance of the Ni-Co-B nanotubes was attributed to their high specific surface area and the characteristic confinement effects, compared with Ni-Co-B nanoparticles.

Two dimensional oxygen-vacancy-rich Co3O4 nanosheets with excellent supercapacitor performances.

A set of identical Co3O4 nanosheets with different oxygen vacancy amounts are rationally designed by varied reduction treatments and comparison of their properties. Remarkably, the oxygen-vacancy-rich Co3O4 nanosheets (OVR-Co3O4 NSs) exhibit excellent electrochemical performance for their potential use as a promising candidate for the next generation of supercapacitors.