Showing papers by "Harbin Engineering University published in 2016"

Carbon materials for high volumetric performance supercapacitors: design, progress, challenges and opportunities

Abstract: Volumetric performance, a much more reliable and precise parameter for evaluating the charge-storage capacity of supercapacitors compared with gravimetric performance, has aroused more and more interest in recent years owing to the rapid development of miniaturized, portable and wearable electronic devices as well as electric vehicles. Various carbon materials are widely used as electrode materials in supercapacitors. However, their intrinsically low specific capacitance and relatively low bulk density lead to a relatively low volumetric performance, significantly limiting their future application. This critical review points out the crucial importance of volumetric performance and reviews recent achievements of high volumetric performances obtained through the rational design and development of novel carbon-based materials. Particular emphasis is focused on discussing the factors influencing the volumetric performance of carbon materials from a structural design point of view. We then make an in-depth summary of various promising approaches used to make significant research breakthroughs in recent years. Current challenges, future research directions and opportunities in this fascinating field of supercapacitors with high gravimetric and volumetric performances are also discussed.

Charge-Convertible Carbon Dots for Imaging-Guided Drug Delivery with Enhanced in Vivo Cancer Therapeutic Efficiency

Abstract: Carbon dots (CDs) are remarkable nanocarriers due to their promising optical and biocompatible capabilities. However, their practical applicability in cancer therapeutics is limited by their insensitive surface properties to complicated tumor microenvironment in vivo. Herein, a tumor extracellular microenvironment-responsive drug nanocarrier based on cisplatin(IV) prodrug-loaded charge-convertible CDs (CDs–Pt(IV)@PEG-(PAH/DMMA)) was developed for imaging-guided drug delivery. An anionic polymer with dimethylmaleic acid (PEG-(PAH/DMMA)) on the fabricated CDs–Pt(IV)@PEG-(PAH/DMMA) could undergo intriguing charge conversion to a cationic polymer in mildly acidic tumor extracellular microenvironment (pH ∼ 6.8), leading to strong electrostatic repulsion and release of positive CDs–Pt(IV). Importantly, positively charged nanocarrier displays high affinity to negatively charged cancer cell membrane, which results in enhanced internalization and effective activation of cisplatin(IV) prodrug in the reductive cytos...

Coupling Hollow Fe3O4–Fe Nanoparticles with Graphene Sheets for High-Performance Electromagnetic Wave Absorbing Material

Abstract: We developed a strategy for coupling hollow Fe3O4–Fe nanoparticles with graphene sheets for high-performance electromagnetic wave absorbing material. The hollow Fe3O4–Fe nanoparticles with average diameter and shell thickness of 20 and 8 nm, respectively, were uniformly anchored on the graphene sheets without obvious aggregation. The minimal reflection loss RL values of the composite could reach −30 dB at the absorber thickness ranging from 2.0 to 5.0 mm, greatly superior to the solid Fe3O4–Fe/G composite and most magnetic EM wave absorbing materials recently reported. Moreover, the addition amount of the composite into paraffin matrix was only 18 wt %.

Observer-Based Fault Detection for Nonlinear Systems With Sensor Fault and Limited Communication Capacity

Abstract: In this technical note, a new fault detection design scheme is proposed for interval type-2 (IT2) Takagi-Sugeno (T-S) fuzzy systems with sensor fault based on a novel fuzzy observer. The parameter uncertainties can be captured by the membership functions of the IT2 fuzzy model. The premise variables of the plant are perfectly shared by the fuzzy observer. A stochastic process between the plant and the observer is considered in the system. A fault sensitive performance is established, and then sufficient conditions are obtained for determining the fuzzy observer gains. Finally, simulation results are provided to verify the effectiveness of the presented scheme.

Network-Based Event-Triggered Control for Singular Systems With Quantizations

Abstract: This paper investigates the problem of event-triggered $H_{\infty}$ control for a networked singular system with both state and input subject to quantizations. First, a discrete event-triggered scheme, which activates only at each sampling instance, is presented. Next, two new sector bound conditions of quantizers are proposed to provide a more intuitive stability analysis and controller design. Then, network conditions, quantizations, and the event-triggered scheme are modeled as a time-delay system. With this model, the criteria are derived for $H_{\infty}$ performance analysis, and codesigning methods are developed for the event trigger and the quantized state feedback controller. An inverted pendulum controlled through the network is given to demonstrate the effectiveness and potential of the new design techniques.

Dissipativity-Based Filtering for Fuzzy Switched Systems With Stochastic Perturbation

Abstract: In this technical note, the problem of the dissipativity-based filtering problem is considered for a class of T-S fuzzy switched systems with stochastic perturbation. Firstly, a sufficient condition of strict dissipativity performance is given to guarantee the mean-square exponential stability for the concerned T-S fuzzy switched system. Then, our attention is focused on the design of a filter to the T-S fuzzy switched system with Brownian motion. By combining the average dwell time technique with the piecewise Lyapunov function technique, the desired fuzzy filters are designed that guarantee the filter error dynamic system to be mean-square exponential stable with a strictly dissipative performance, and the corresponding solvability condition for the fuzzy filter is also presented based on the linearization procedure approach. Finally, an example is provided to illustrate the effectiveness of the proposed dissipativity-based filter technique.

Output-Feedback Based Sliding Mode Control for Fuzzy Systems With Actuator Saturation

Abstract: In this paper, a novel adaptive sliding mode controller is designed for Takagi–Sugeno (T–S) fuzzy systems with actuator saturation and system uncertainty. By the delta operator approach, the discrete-time nonlinear system is described by a T–S fuzzy model with unmeasurable state. By singular value decomposition of system input matrix, a reduced-order system is obtained for the design of sliding mode surface. A new adaptive sliding mode controller based on system output is presented to guarantee that the closed-loop system is uniformly ultimately bounded. Four examples are provided to illustrate the effectiveness and applicability of the proposed control scheme.

Integration of Upconversion Nanoparticles and Ultrathin Black Phosphorus for Efficient Photodynamic Theranostics under 808 nm Near-Infrared Light Irradiation

Abstract: A proper photosensitizer and increased penetration depth are still two major challenges in photodynamic therapy (PDT). The conventional ultraviolet/visible irradiation light has low tissue penetration, which thus limits its clinical application. Herein, we for the first time designed a novel multifunctional composite by integrating NaGdF4:Yb,Er@Yb@Nd@Yb upconversion nanoparticles (UCNPs) and black phosphorus sheets (BPS) for a single 808 nm laser light-mediated PDT. UCNPs, which served as the energy donor, were modified with poly(acrylic acid), and the BPS were stabilized by the PEG-NH2; then the two counterparts were integrated into the UCNPs–BPS composite via electrostatic interaction. Under 808 nm near-infrared light irradiation, the composite exhibits excellent antitumor efficiency because of the large amount of reactive oxygen species generated compared with those under 650 and 980 nm irradiations with the same pump power, which has evidently been confirmed by in vitro and in vivo results. In particu...

Biomass-derived three-dimensional honeycomb-like hierarchical structured carbon for ultrahigh energy density asymmetric supercapacitors

Abstract: Porous carbon materials derived from various biomasses have aroused intense interest from the scientific community due to their low cost, abundant resources, eco-friendliness and easy fabrication. Herein, three-dimensional honeycomb-like hierarchical structured carbon (HSC) has been fabricated by one-step carbonization/activation of abundant and low cost bacterial cellulose for ultrahigh energy density supercapacitors. Benefitting from its interconnected honeycomb-like hierarchical and open structure with a high specific surface area, the prepared HSC exhibits a superhigh specific capacitance of 422 F g−1 at 2 mV s−1 with remarkable rate performance (73.7% at 500 mV s−1) in 6 M KOH aqueous electrolyte. Meanwhile, the symmetric supercapacitor could deliver a high energy density of 37.3 W h kg−1 in 1 M Na2SO4 aqueous electrolyte. To evaluate the practical application, an asymmetric supercapacitor fabricated with NiCoAl-layered double hydroxide as the positive electrode and HSC as the negative electrode achieves a conspicuously high energy density of 100 W h kg−1 and could still retain 33 W h kg−1 even at a high power density of 36.8 kW kg−1, which is highly comparable with or even higher than those of the previously reported asymmetric supercapacitors in aqueous electrolytes. Furthermore, our asymmetric supercapacitor exhibits excellent cycling stability along with 113% capacitance retention after 10 000 cycles. Such spectacular results will shed new light on biomass-derived carbon materials for the next generation of ultrafast energy storage devices with high energy density and excellent long cycle life.

Hybrid metamaterial switching for manipulating chirality based on VO2 phase transition

Abstract: Polarization manipulations of electromagnetic waves can be obtained by chiral and anisotropic metamaterials routinely, but the dynamic and high-efficiency modulations of chiral properties still remain challenging at the terahertz range. Here, we theoretically demonstrate a new scheme for realizing thermal-controlled chirality using a hybrid terahertz metamaterial with embedded vanadium dioxide (VO2) films. The phase transition of VO2 films in 90° twisted E-shaped resonators enables high-efficiency thermal modulation of linear polarization conversion. The asymmetric transmission of linearly polarized wave and circular dichroism simultaneously exhibit a pronounced switching effect dictated by temperature-controlled conductivity of VO2 inclusions. The proposed hybrid metamaterial design opens exciting possibilities to achieve dynamic modulation of terahertz waves and further develop tunable terahertz polarization devices.

Robust student’s t based nonlinear filter and smoother

Abstract: Novel Student’s t based approaches for formulating a filter and smoother, which utilize heavy tailed process and measurement noise models, are found through approximations of the associated posterior probability density functions. Simulation results for manoeuvring target tracking illustrate that the proposed methods substantially outperform existing methods in terms of the root mean square error.

g-C3N4 Coated Upconversion Nanoparticles for 808 nm Near-Infrared Light Triggered Phototherapy and Multiple Imaging

Abstract: Exploring novel photosensitizer (PS) with good stability and high light converting efficiency and designing novel structure to integrate deep penetrating near-infrared (NIR) light excitable up-conversion nanoparticles (UCNPs) and PS into one system are highly fascinating in the photodynamic therapy (PDT) field. In this study, a novel core–shell structured platform (UCNPs@g-C3N4–PEG) with all-in-one “smart” functions for simultaneous photodynamic therapy, photothermal therapy (PTT), and trimodal imaging properties has been rationally designed and fabricated. This system is composed of a core–shell–shell structured NaGdF4:Yb/Tm@NaGdF4:Yb@NaNdF4:Yb up-conversion luminescence (UCL) core and photoactive graphitic-phase carbon nitride (g-C3N4) mesoporous shell closely coated on individual core. This designed structure allows large specific surface area, high loading amount, close proximity to the UCL core, and almost no leakage of g-C3N4 PS, thus ensuring sufficient reactive oxygen species (ROS) to damage tumor...

Two-dimensional net-like SnO2/ZnO heteronanostructures for high-performance H2S gas sensor

Abstract: H2S gas in the environment, even at a concentration as low as 20 ppb, is very harmful to the health of human beings. Therefore, the design and fabrication of sensors for detecting trace H2S gas in the environment are highly desirable. However, it remains a challenge to develop gas sensors that can detect H2S at ppb concentration levels and at a relatively low temperature. Herein we developed a facile method to fabricate porous two-dimensional net-like SnO2/ZnO heteronanostructures. Both the SnO2 and ZnO nanoparticles were significantly smaller in the net-like heteronanostructures than in net-like SnO2 and ZnO homonanostructures. Heterojunctions formed at the interfaces between SnO2 and ZnO—and, as a result, the net-like SnO2/ZnO heteronanostructures—exhibited better H2S-sensing properties, including higher sensor response, better selectivity and long-term stability, than did the net-like SnO2 and ZnO homonanostructures, and other types of metal oxide-based nanocomposites. Importantly, the SnO2/ZnO heteronanostructures could detect 10 ppb H2S even at a working temperature of 100 °C. Therefore, the net-like SnO2/ZnO heteronanostructures have very promising applications in high-performance H2S sensors. In addition, the fabrication method presented here is facile, repeatable and operable, and may thus be extended to synthesize other types of metal oxide-based heteronanostructures for applications in various fields.

N-Doped TiO2 Nanobelts with Coexposed (001) and (101) Facets and Their Highly Efficient Visible-Light-Driven Photocatalytic Hydrogen Production.

Abstract: To narrow the band gap (3.2 eV) of TiO2 and extend its practical applicability under sunlight, the doping with nonmetal elements has been used to tune TiO2 electronic structure. However, the doping also brings new recombination centers among the photoinduced charge carriers, which results in a quantum efficiency loss accordingly. It has been proved that the {101} facets of anatase TiO2 are beneficial to generating and transmitting more reductive electrons to promote the H2-evolution in the photoreduction reaction, and the {001} facets exhibit a higher photoreactivity to accelerate the reaction involved of photogenerated hole. Thus, it was considered by us that using the surface heterojunction composed of both {001} and {101} facets may depress the disadvantage of N doping. Fortunately, we successfully synthesized anatase N-doped TiO2 nanobelts with a surface heterojunction of coexposed (101) and (001) facets. As expected, it realized the charge pairs’ spatial separation and showed higher photocatalytic ac...

Hollow CoP nanopaticle/N-doped graphene hybrids as highly active and stable bifunctional catalysts for full water splitting

Abstract: An alkaline electrolyzer fabricated by employing hollow CoP nanoparticles/N-doped graphene as bifunctional catalysts exhibits remarkable activity with a current density of 10 mA cm−2 at a cell voltage of 1.58 V and considerable stability over 65 h of continuous electrolysis operation, favorably comparable to the integrated performance of commercial Pt/C and IrO2.

A graphene oxide/amidoxime hydrogel for enhanced uranium capture.

Abstract: The efficient development of selective materials for the recovery of uranium from nuclear waste and seawater is necessary for their potential application in nuclear fuel and the mitigation of nuclear pollution. In this work, a graphene oxide/amidoxime hydrogel (AGH) exhibits a promising adsorption performance for uranium from various aqueous solutions, including simulated seawater. We show high adsorption capacities (Qm = 398.4 mg g−1) and high % removals at ppm or ppb levels in aqueous solutions for uranium species. In the presence of high concentrations of competitive ions such as Mg2+, Ca2+, Ba2+ and Sr2+, AGH displays an enhanced selectivity for uranium. For low uranium concentrations in simulated seawater, AGH binds uranium efficiently and selectively. The results presented here reveal that the AGH is a potential adsorbent for remediating nuclear industrial effluent and adsorbing uranium from seawater.

Molten salt synthesis of nitrogen doped porous carbon: a new preparation methodology for high-volumetric capacitance electrode materials

Abstract: To meet the ever-increasing need for high-efficiency energy storage in modern society, porous carbon materials with large surface areas are typically employed for electrical double-layer capacitors to achieve high gravimetric performances. However, their poor volumetric performances come from low packing density and/or high pore volume resulting in poor volumetric capacitance, which would limit their further applications. Here, a novel and one-step molten salt synthesis of a three-dimensional, densely nitrogen-doped porous carbon (NPC) material by using low-cost and eco-friendly tofu as the nitrogen-containing carbon source is proposed. Hierarchically porous carbon with a specific surface area of 1202 m2 g−1 and a high nitrogen content of 4.72 wt% and a bulk density of ∼0.84 g cm−3 is obtained at a carbonation temperature of 750 °C. As the electrode material for a supercapacitor, the NPC electrode shows both ultra-high specific volumetric and gravimetric capacitances of 360 F cm−3 and 418 F g−1 at 1 A g−1 (based on a three-electrode system), respectively, and excellent cycling stability without capacitance loss after 10 000 cycles at a high charge current of 10 A g−1 in KOH electrolyte. Moreover, the as-assembled symmetric supercapacitor exhibits not only an excellent cycling stability with 97% capacitance retention after 10 000 cycles, but also a high volumetric energy density up to 27.68 W h L−1 at a current density of 0.2 A g−1, making this new method highly promising for compact energy storage devices with simultaneous high volumetric/gravimetric energy and power densities.

Construction of nitrogen-doped porous carbon buildings using interconnected ultra-small carbon nanosheets for ultra-high rate supercapacitors

Abstract: Here, for the first time, we demonstrate a facile one-step construction of a nitrogen-doped porous carbon building (N-PCB) using interconnected ultra-small carbon nanosheets through the carbonization of biomass (Auricularia) using ZnCl2 as the activating agent and NH4Cl as the nitrogen source. Due to its high specific surface area (1607 m2 g−1) with a high mesopore ratio (91%), interconnected porous structure with short ion diffusion paths, and nitrogen doping (4.8 at%), the N-PCB electrode exhibits a high specific capacitance of 347 F g−1 at 1 A g−1, excellent rate capability (278 F g−1 at 50 A g−1, 80% of capacitance retention) and outstanding cycling stability (only 2% loss in specific capacitance after 10 000 cycles). Moreover, the assembled N-PCB symmetric supercapacitor is stabilized with excellence cycling stability (4% loss after 20 000 cycles) at 1.6 V in 1 M Na2SO4 aqueous electrolyte, delivering a high energy density of 22 W h kg−1, much higher than that of most of the reported carbon-based symmetric supercapacitors in aqueous electrolytes. Therefore, these exciting results suggest a low-cost and environmentally friendly design of electrode materials for high-performance supercapacitors.