Construction of hierarchical CuO/Cu2O@NiCo2S4 Nanowire arrays on copper foam for high performance supercapacitor electrodes

Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu2O@NiCo2S4) core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu2O nanowire arrays are firstly grown on Cu foam by one-step thermal oxidation of Cu foam, followed by electrodeposition of NiCo2S4 nanosheets on the surface of CuO/Cu2O nanowires to form the CuO/Cu2O@NiCo2S4 core-shell nanostructures. Structural and morphological characterizations indicate that the average thickness of the NiCo2S4 nanosheets is ~20 nm and the diameter of CuO/Cu2O core is ~50 nm. Electrochemical properties of the hierarchical composites as integrated binder-free electrodes for supercapacitor were evaluated by various electrochemical methods. The hierarchical composite electrodes could achieve ultrahigh specific capacitance of 3.186 F cm-2 at 10 mA cm-2, good rate capability (82.06% capacitance retention at the current density from 2 to 50 mA cm-2) and excellent cycling stability, with capacitance retention of 96.73% after 2000 cycles at 10 mA cm-2. These results demonstrate the significance of optimized design and fabrication of electrode materials with more sufficient electrolyte-electrode interface, robust structural integrity and fast ion/electron transfer. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.21371057, NSFC, National Natural Science Foundation of ChinaNational Key R&D Program of China [2016YFE0131200]; National Natural Science Foundation of China [21371057]; International Cooperation Project of Shanghai Municipal Science and Technology Committee [15520721100

Co3O4@CoS core-shell nanosheets on carbon cloth for high performance supercapacitor electrodes

In this work, a two-step electrodeposition strategy is developed for the synthesis of core-shell Co3O4@CoS nanosheet arrays on carbon cloth (CC) for supercapacitor applications. Porous Co3O4 nanosheet arrays are first directly grown on CC by electrodeposition, followed by the coating of a thin layer of CoS on the surface of Co3O4 nanosheets via the secondary electrodeposition. The morphology control of the ternary composites can be easily achieved by altering the number of cyclic voltammetry (CV) cycles of CoS deposition. Electrochemical performance of the composite electrodes was evaluated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques. The results demonstrate that the Co3O4@CoS/CC with 4 CV cycles of CoS deposition possesses the largest specific capacitance 887.5 F·g-1 at a scan rate of 10 mV·s-1 (764.2 F·g-1 at a current density of 1.0 A·g-1), and excellent cycling stability (78.1% capacitance retention) at high current density of 5.0 A·g-1 after 5000 cycles. The porous nanostructures on CC not only provide large accessible surface area for fast ions diffusion, electron transport and efficient utilization of active CoS and Co3O4, but also reduce the internal resistance of electrodes, which leads to superior electrochemical performance of Co3O4@CoS/CC composite at 4 cycles of CoS deposition. © 2017 by the authors.National Natural Science Foundation of China [21371057]; International Science and Technology Cooperation Program of China [2016YFE0131200, 2015DFA51220]; International Cooperation Project of Shanghai Municipal Science and Technology Committee [15520721100

3D porous Ti3C2 MXene/NiCo-MOF composites for enhanced lithium storage

To improve Li storage capacity and the structural stability of Ti3C2 MXene-based electrode materials for lithium-ion batteries (LIBs), a facile strategy is developed to construct three-dimensional (3D) hierarchical porous Ti3C2/bimetal-organic framework (NiCo-MOF) nanoarchitectures as anodes for high-performance LIBs. 2D Ti3C2 nanosheets are coupled with NiCo-MOF nanoflakes induced by hydrogen bonds to form 3D Ti3C2/NiCo-MOF composite films through vacuum-assisted filtration technology. The morphology and electrochemical properties of Ti3C2/NiCo-MOF are influenced by the mass ratio of MOF to Ti3C2. Owing to the interconnected porous structures with a high specific surface area, rapid charge transfer process, and Li+ di. © 2020 by the authors.National Natural Science Foundation of ChinaNational Natural Science Foundation of China [51702098]; National Key R&D Program of China [2016YFE0131200]; International Cooperation Project of Shanghai Municipal Science and Technology Committee [18520744400

Hierarchical PANI/NiCo-LDH core-shell composite networks on carbon cloth for high performance asymmetric supercapacitor

In this work, a facile two-step strategy is adopted to construct hierarchical polyaniline/ NiCo-layered double hydroxide (PANI/NiCo-LDH) core-shell composite nanofiber networks on carbon cloth (CC). Three-dimensional (3D) porous PANI nanofiber networks are firstly uniformly anchored on CC by in-situ oxidative polymerization, followed by growth of NiCo-LDH nanoflakes on the crosslinked PANI framework via electrochemical deposition. The morphology and electrochemical properties of PANI/NiCo-LDH composites are controlled by the deposition time of LDH. Benefiting from rapid electron transport and ion diffusion, the well-defined PANI/NiCo-LDH hierarchical composite with 200 s deposition of LDH delivers a large capacitance of 1845 F g -1 at 0.5 A g -1 and excellent cycling stability of 82% capacitance retention after 5000 cycles at a very high current density of 10.0 A g -1 . Furthermore, an asymmetric supercapacitor (ASC) assembled with PANI/NiCo-LDH as a positive electrode and activated carbon (AC) as a negative electrode exhibits a high capacitance of 147.2 F g -1 in a potential range from 0 to 1.5 V and superior energy density of 46.0 Wh kg -1 at a power density of 351.6W kg -1 . © 2019 by the authors. Licensee MDPI, Basel, Switzerland.National Key R&D Program of China [2016YFE0131200]; National Natural Science Foundation of China [51702098]; International Cooperation Project of Shanghai Municipal Science and Technology Committee [18520744400]; Ministry of Education, Youth, and Sports of the Czech Republic [LTACH17015

Astrocytes from the contused spinal cord inhibit oligodendrocyte differentiation of adult oligodendrocyte precursor cells by increasing the expression of bone morphogenetic proteins.

Promotion of remyelination is an important therapeutic strategy to facilitate functional recovery after traumatic spinal cord injury (SCI). Transplantation of neural stem cells (NSCs) or oligodendrocyte precursor cells (OPCs) has been used to enhance remyelination after SCI. However, the microenvironment in the injured spinal cord is inhibitory for oligodendrocyte (OL) differentiation of NSCs or OPCs. Identifying the signaling pathways that inhibit OL differentiation in the injured spinal cord could lead to new therapeutic strategies to enhance remyelination and functional recovery after SCI. In the present study, we show that reactive astrocytes from the injured rat spinal cord or their conditioned media inhibit OL differentiation of adult OPCs with concurrent promotion of astrocyte differentiation. The expression of bone morphogenetic proteins (BMP) is dramatically increased in the reactive astrocytes and their conditioned media. Importantly, blocking BMP activity by BMP receptor antagonist, noggin, reverse the effects of active astrocytes on OPC differentiation by increasing the differentiation of OL from OPCs while decreasing the generation of astrocytes. These data indicate that the upregulated bone morphogenetic proteins in the reactive astrocytes are major factors to inhibit OL differentiation of OPCs and to promote its astrocyte differentiation. These data suggest that manipulation of BMP signaling in the endogenous or grafted NSCs or OPCs may be a useful therapeutic strategy to increase their OL differentiation and remyelination and enhance functional recovery after SCI

Transplantation of Ciliary Neurotrophic Factor-Expressing Adult Oligodendrocyte Precursor Cells Promotes Remyelination and Functional Recovery after SpinalCord Injury

Demyelination contributes to the dysfunction after traumatic spinal cord injury (SCI). We explored whether the combination of neurotrophic factors and transplantation of adult rat spinal cord oligodendrocyte precursor cells (OPCs) could enhance remyelination and functional recovery after SCI. Ciliary neurotrophic factor (CNTF) was the most effective neurotrophic factor to promote oligodendrocyte (OL) differentiation and survival of OPCs in vitro. OPCs were infected with retroviruses expressing enhanced green fluorescent protein (EGFP) or CNTF and transplanted into the contused adult thoracic spinal cord 9 d after injury. Seven weeks after transplantation, the grafted OPCs survived and integrated into the injured spinal cord. The survival of grafted CNTF-OPCs increased fourfold compared with EGFP-OPCs. The grafted OPCs differentiated into adenomatus polyposis coli (APC+) OLs, and CNTF significantly increased the percentage of APC+ OLs from grafted OPCs. Immunofluorescent and immunoelectron microscopic analyses showed that the grafted OPCs formed central myelin sheaths around the axons in the injured spinal cord. The number of OL-remyelinated axons in ventrolateral funiculus (VLF) or lateral funiculus (LF) at the injured epicenter was significantly increased in animals that received CNTF-OPC grafts compared with all other groups. Importantly, 75% of rats receiving CNTF-OPC grafts recovered transcranial magnetic motor-evoked potential and magnetic interenlargement reflex responses, indicating that conduction through the demyelinated axons in VLF or LF, respectively, was partially restored. More importantly, recovery of hindlimb locomotor function was significantly enhanced in animals receiving grafts of CNTF-OPCs. Thus, combined treatment with OPC grafts expressing CNTF can enhance remyelination and facilitate functional recovery after traumatic SCI

Copper-doped nano laponite coating on poly(butylene succinate) scaffold with antibacterial properties and cytocompatibility for biomedical application

An ideal artificial bone will likely be multifunctional, combining different technologies to simultaneously promote bone regeneration while inhibiting microbial infection. In this study, copper- (Cu-) doped nano laponite (cnLAP) was prepared by a cation-exchanged method, and the cnLAP coating on poly(butylene succinate) (PBSu) scaffold was fabricated by poly(dopamine) modification. The results showed that incorporation of Cu ions into nano laponite (nLAP) did not have obvious effects on the morphology and surface area of cnLAP (compared with nLAP), which could be coated easily on macroporous PBSu scaffolds. In addition, the cnLAP-coated PBSu scaffolds could inhibit the growth of both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), indicating good antibacterial activity. Moreover, the cnLAP-coated PBSu scaffolds significantly promoted proliferation and improved alkaline phosphatase (ALP) activity of bone mesenchymal stem cells (BMSCs) compared with PBSu scaffolds. Furthermore, no obvious differences in cell responses to cnLAP- and nLAP-coated PBSu scaffolds were found, indicating that incorporation of Cu into nLAP had no negative effects on its cytocompatibility. The results suggested that the cnLAP-coated PBSu scaffolds exhibited excellent cytocompatibility and antimicrobial activity, which might offer promising opportunities for promoting bone regeneration and prevention of infectious from bacteria and effective treatment of bone defects.National Natural Science Foundation of China [51772194, 81771990]; Key Medical Program of Science and Technology Development of Shanghai [17441900600, 15441902500]; Ministry of Education, Youth and Sports of the Czech Republic Program NPU I [LO1504

Fe3o4 nanoparticles on 3D porous carbon skeleton derived from rape pollen for high-performance Li-ion capacitors

Herein, a three-dimensional (3D) Fe3O4@C composite with hollow porous structure is prepared by simple solution method and calcination treatment with biomass waste rape pollen (RP) as a carbon source, which is served as an anode of Li-ion capacitor (LIC). The 3D interconnected porous structure and conductive networks facilitate the transfer of ion/electron and accommodate the volume changes of Fe3O4 during the electrochemical reaction process, which leads to the excellent performance of the Fe3O4@C composite electrode. The electrochemical analysis demonstrates that the hybrid LIC fabricated with Fe3O4@C as the anode and activated carbon (AC) as the cathode can operate at a voltage of 4.0 V and exhibit a high energy density of 140.6 Wh kg−1 at 200 W kg−1 (52.8 Wh kg−1 at 10 kW kg−1), along with excellent cycling stability, with a capacity retention of 83.3% over 6000 cycles. Hence, these encouraging results indicate that Fe3O4@C has great potential in developing advanced LICs electrode materials for the next generation of energy storage systems. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.LTT20005; 18520744400; National Natural Science Foundation of China, NSFC: 22075082National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [22075082]; International Cooperation Project of Shanghai Municipal Science, Technology Committee [18520744400]; Czech Ministry of Education, Youth and Sports INTER-EXCELLENCE program [LTT20005

A highly flexible supercapacitor based on MnO2/RGO nanosheets and bacterial cellulose-filled gel electrolyte

The flexible supercapacitors (SCs) of the conventional sandwich-type structure have poor flexibility due to the large thickness of the final entire device. Herein, we have fabricated a highly flexible asymmetric SC using manganese dioxide (MnO2) and reduced graphene oxide (RGO) nanosheet-piled hydrogel films and a novel bacterial cellulose (BC)-filled polyacrylic acid sodium salt-Na2SO4 (BC/PAAS-Na2SO4) neutral gel electrolyte. Apart from being environmentally friendly, this BC/PAAS-Na2SO4 gel electrolyte has high viscosity and a sticky property, which enables it to combine two electrodes together. Meanwhile, the intertangling of the filled BC in the gel electrolyte hinders the decrease of the viscosity with temperature, and forms a separator to prevent the two electrodes from short-circuiting. Using these materials, the total thickness of the fabricated device does not exceed 120 μm. This SC device demonstrates high flexibility, where bending and even rolling have no obvious effect on the electrochemical performance. In addition, owing to the asymmetric configuration, the cell voltage of this flexible SC has been extended to 1.8 V, and the energy density can reach up to 11.7 Wh kg-1 at the power density of 441 W kg-1. This SC also exhibits a good cycling stability, with a capacitance retention of 85.5% over 5000 cycles. © 2017 by the authors.Ministry of Education, Youth, and Sports of the Czech Republic [LTACH17015]; NPU Program I [LO1504]; Operational Program Research and Development for Innovations - European Regional Development Fund (ERDF); national budget of the Czech Republic within the framework of the CPSstrengthening research capacity [CZ.1.05/2.1.00/19.0409]; Tomas Bata University in Zlin, Czech Republic [IGA/CPS/2015/008, IGA/CPS/2016/003

Block-Wise Mixed-Precision Quantization: Enabling High Efficiency for Practical ReRAM-based DNN Accelerators

Resistive random access memory (ReRAM)-based processing-in-memory (PIM) architectures have demonstrated great potential to accelerate Deep Neural Network (DNN) training/inference. However, the computational accuracy of analog PIM is compromised due to the non-idealities, such as the conductance variation of ReRAM cells. The impact of these non-idealities worsens as the number of concurrently activated wordlines and bitlines increases. To guarantee computational accuracy, only a limited number of wordlines and bitlines of the crossbar array can be turned on concurrently, significantly reducing the achievable parallelism of the architecture. While the constraints on parallelism limit the efficiency of the accelerators, they also provide a new opportunity for fine-grained mixed-precision quantization. To enable efficient DNN inference on practical ReRAM-based accelerators, we propose an algorithm-architecture co-design framework called \underline{B}lock-\underline{W}ise mixed-precision \underline{Q}uantization (BWQ). At the algorithm level, BWQ-A introduces a mixed-precision quantization scheme at the block level, which achieves a high weight and activation compression ratio with negligible accuracy degradation. We also present the hardware architecture design BWQ-H, which leverages the low-bit-width models achieved by BWQ-A to perform high-efficiency DNN inference on ReRAM devices. BWQ-H also adopts a novel precision-aware weight mapping method to increase the ReRAM crossbar's throughput. Our evaluation demonstrates the effectiveness of BWQ, which achieves a 6.08x speedup and a 17.47x energy saving on average compared to existing ReRAM-based architectures.Comment: 12 pages, 13 figure