Harbin Engineering University

About: Harbin Engineering University is a education organization based out in Harbin, Heilongjiang, China. It is known for research contribution in the topics: Control theory & Microstructure. The organization has 31149 authors who have published 27940 publications receiving 276787 citations. The organization is also known as: HEU.

Uniformly Dispersed ZnFe 2 O 4 Nanoparticles on Nitrogen-Modified Graphene for High-Performance Supercapacitor as Electrode

Abstract: A facile strategy has been adopted for the preparation of ZnFe2O4/NRG composite by anchoring ultrasmall ZnFe2O4 nanoparticles on nitrogen-doped reduced graphene (denoted as NRG) for high-performance supercapacitor electrode. Remarkably, the growth of ZnFe2O4 nanocrystals, the reduction of graphitic oxide and the doping of nitrogen to graphene have been simultaneously achieved in one process. It is found that the NRG employed as substrate can not only control the formation of nano-sized ZnFe2O4, but also guarantee the high dispersion without any agglomeration. Benefiting from this novel combination and construction, the hybrid material has large surface area which can provide high exposure of active sites for easy access of electrolyte and fast electron transport. When served as supercapacitor electrode, the ZnFe2O4/NRG composite exhibits a favorable specific capacitance of 244 F/g at 0.5 A/g within the potential range from −1 to 0 V, desirable rate stability (retain 131.5 F/g at 10 A/g) and an admirable cycling durability of 83.8% at a scan rate of 100 mV/s after 5000 cycles. When employed as symmetric supercapacitor, the device demonstrates favorable performance. These satisfactory properties of the ZnFe2O4/NRG composite can make it be of great promise in the supercapacitor application.

Direct Electrochemistry of Multi-Copper Oxidases at Carbon Nanotubes Noncovalently Functionalized with Cellulose Derivatives

Abstract: This study describes the direct electron transfer of multi-copper oxidases, i.e., laccase (from Trametes versicolor) and bilirubin oxidase (BOD, from Myrothecium verrucaria) at multiwalled carbon nanotubes (MWNTs) noncovalently functionalized with biopolymers of cellulose derivatives, i.e., hydroxyethyl cellulose (HEC), methyl cellulose (MC), and carboxymethyl cellulose (CMC). The functionalization of the MWNTs with the cellulose derivatives is found to substantially solubilize the MWNTs into aqueous media and to avoid their aggregation on electrode surface. Under anaerobic conditions, the redox properties of laccase and BOD are difficult to be defined with cyclic voltammetry at either laccase/MWNT-modified or BOD/MWNT-modified electrodes. The direct electron transfer properties of laccase and BOD are thus studied in terms of the bioelectrocatalytic activities of the laccase/MWNT-modified and BOD/MWNT-modified electrodes toward the reduction of oxygen and found to be facilitated at the functionalized MWNTs. The possible application of the laccase-catalyzed O2 reduction at the laccase/MWNT-modified electrode is illustrated by constructing a CNT-based ascorbate/O2 biofuel cell with the MWNT-modified electrode as the anode for the oxidation of ascorbate biofuel.

Superior sodium intercalation of honeycomb-structured hierarchical porous Na3V2(PO4)3/C microballs prepared by a facile one-pot synthesis

Abstract: Tailoring materials into a hierarchical porous micro/nanostructure offers unprecedented opportunities in the utilization of their functional properties. Particularly, it is crucial for the electrode materials to realize high-performance because of the advantages such as large surface area, superior structure stability and short ion transport pathway. Here we report the design of a new architecture, named “honeycomb-type hierarchical porous microball”, for Na3V2(PO4)3 by a facile one-pot synthesis. The network between nanovoids is formed by in situ carbonization of surfactants (CTAB) along with the crystallization of Na3V2(PO4)3, which results in the hierarchical porous Na3V2(PO4)3 skeleton with a surface conductive layer. The prepared Na3V2(PO4)3/C composite consists of spherical particles filled with hierarchical pores and interconnective nanochannels, resulting in the honeycomb-type architecture. It not only enables easier electrolyte penetration, but also provides a high-efficiency electron/ion transport pathway for fast sodium intercalation. Both the GITT and EIS results demonstrate the improved sodium diffusion capability and decreased electrochemical resistance for the honeycomb-structured microball in comparison to the microsized nonporous reference samples. Moreover, it also delivers superior high rate capability and cycling stability, which retains 93.6% of the initial capacity after 200 cycles at the 1 C rate. Even at 20 C, it still delivers a high capacity of 80.2 mA h g−1 corresponding to 71% of the capacity. Given the superior ion intercalation kinetics and excellent structure stability, the honeycomb-type structure puts forward a new strategy to develop high-performance polyanion-based materials for low-cost and high-power “rocking-chair” batteries.