Daohao Li

Egg-Box Structure in Cobalt Alginate: A New Approach to Multifunctional Hierarchical Mesoporous N-Doped Carbon Nanofibers for Efficient Catalysis and Energy Storage

Carbon nanomaterials with both doped heteroatom and porous structure represent a new class of carbon nanostructures for boosting electrochemical application, particularly sustainable electrochemical energy conversion and storage applications. We herein demonstrate a unique large-scale sustainable biomass conversion strategy for the synthesis of earth-abundant multifunctional carbon nanomaterials with well-defined doped heteroatom level and multimodal pores through pyrolyzing electrospinning renewable natural alginate. The key part for our chemical synthesis is that we found that the egg-box structure in cobalt alginate nanofiber can offer new opportunity to create large mesopores (∼10–40 nm) on the surface of nitrogen-doped carbon nanofibers. The as-prepared hierarchical carbon nanofibers with three-dimensional pathway for electron and ion transport are conceptually new as high-performance multifunctional electrochemical materials for boosting the performance of oxygen reduction reaction (ORR), lithium ion batteries (LIBs), and supercapacitors (SCs). In particular, they show amazingly the same ORR activity as commercial Pt/C catalyst and much better long-term stability and methanol tolerance for ORR than Pt/C via a four-electron pathway in alkaline electrolyte. They also exhibit a large reversible capacity of 625 mAh g–1 at 1 A g–1, good rate capability, and excellent cycling performance for LIBs, making them among the best in all the reported carbon nanomaterials. They also represent highly efficient carbon nanomaterials for SCs with excellent capacitive behavior of 197 F g–1 at 1 A g–1 and superior stability. The present work highlights the importance of biomass-derived multifunctional mesoporous carbon nanomaterials in enhancing electrochemical catalysis and energy storage.

Simple pyrolysis of cobalt alginate fibres into Co3O4/C nano/microstructures for a high-performance lithium ion battery anode

Cobalt tetroxide (Co3O4) has attracted much attention as a promising anode material for rechargeable lithium-ion batteries (LIBs) owing to its high theoretical capacity (890 mA h g−1). However, its poor electronic conductivity and weak ability to accommodate large volume changes during a repeated charging–discharging process, which results in the poor cycling performance, have hindered the practical application of Co3O4. In this article, Co3O4/C fibres were prepared by simple pyrolysis of wetspun cobalt alginate fibres. The composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). It was found that the resulting material possesses a unique hierarchical nano/microstructure in which Co3O4 nanoparticles (NPs) are capsulated in a micro-sized carbonaceous fibrous matrix. This nano/microstructure can combine the merits of the Co3O4 nanostructure and the carbonaceous microfibre matrix, and thus exhibits a high reversible capacity of 780 mA h g−1 at 89 mA g−1 after 100 cycles as well as excellent cycling stability and rate performance when used as an anode material. This finding could open up a new direction in sustainable use of natural seaweed resources as new energy storage materials.

Tuning the Shell Number of Multishelled Metal Oxide Hollow Fibers for Optimized Lithium-Ion Storage

Searching the long-life transition-metal oxide (TMO)-based materials for future lithium-ion batteries (LIBs) is still a great challenge because of the mechanical strain resulting from volume change of TMO anodes during the lithiation/delithiation process. To well address this challenging issue, we demonstrate a controlled method for making the multishelled TMO hollow microfibers with tunable shell numbers to achieve the optimal void for efficient lithium-ion storage. Such a particularly designed void can lead to a short diffusion distance for fast diffusion of Li+ ions and also withstand a large volume variation upon cycling, both of which are the key for high-performance LIBs. Triple-shelled TMO hollow microfibers are a quite stable anode material for LIBs with high reversible capacities (NiO: 698.1 mA h g-1 at 1 A g-1; Co3O4: 940.2 mA h g-1 at 1 A g-1; Fe2O3: 997.8 mA h g-1 at 1 A g-1), excellent rate capability, and stability. The present work opens a way for rational design of the void of multiple shells in achieving the stable lithium-ion storage through the biomass conversion strategy.

Double-Helix Structure in Carrageenan–Metal Hydrogels: A General Approach to Porous Metal Sulfides/Carbon Aerogels with Excellent Sodium-Ion Storage

The metal sulfide-carbon nanocomposite is a new class of anode material for sodium ion batteries, but its development is restricted by its relative poor rate ability and cyclic stability. Herein, we report the use of double-helix structure of carrageenan-metal hydrogels for the synthesis of 3D metal sulfide (Mx Sy ) nanostructure/carbon aerogels (CAs) for high-performance sodium-ion storage. The method is unique, and can be used to make multiple Mx Sy /CAs (such as FeS/CA, Co9 S8 /CA, Ni3 S4 /CA, CuS/CA, ZnS/CA, and CdS/CA) with ultra-small nanoparticles and hierarchical porous structure by pyrolyzing the carrageenan-metal hydrogels. The as-prepared FeS/CA exhibits a high reversible capacity and excellent cycling stability (280 mA h-1 at 0.5 A g-1 over 200 cycles) and rate performance (222 mA h-1 at 5 A g-1 ) when used as the anode material for sodium-ion batteries. The work shows the value of biomass-derived metal sulfide-carbon heterostuctures in sodium-ion storage.

Nanoscale engineering of nitrogen-doped carbon nanofiber aerogels for enhanced lithium ion storage

We developed a unique industrial-scale sustainable biomass conversion strategy for the synthesis of multifunctional, three-dimensional (3D) carbon nanofiber (CNF) aerogels with hierarchical porosity. The above aerogels were also highly nitrogen-doped through pyrolysis of bamboo cellulose. The important and critical part of our synthesis strategy was to assemble the nanofibers of cellulose (NFC) from bamboo to make aerogels of controlled porosity with a hierarchical porous structure. The as-prepared CNF aerogels with abundant chemical reaction sites and three-dimensional electron and ion transport pathways were found to be new high-performance anode materials for lithium-ion batteries (LIBs). In particular, the N-doped CNF aerogel prepared with 1 D fibers of 50 nm in diameter as building-blocks exhibited a high reversible capacity of 630.7 mA h g−1 at 1 A g−1, excellent rate capability (289 mA h g−1 at 20 A g−1) and excellent cycling performance (651 mA h g−1 at 1 A g−1 after 1000 cycles) in LIBs.

Highly stable supercapacitors with MOF-derived Co9S8/carbon electrodes for high rate electrochemical energy storage

Co9S8 has received intensive attention as an electrode material for electrical energy storage (EES) systems due to its unique structural features and rich electrochemical properties. However, the instability and inferior rate capability of the Co9S8 electrode material during the charge/discharge process has restricted its applications in supercapacitors (SCs). Here, MOF-derived Co9S8 nanoparticles (NPs) embedded in carbon co-doped with N and S (Co9S8/NS–C) were synthesized as a high rate capability and super stable electrode material for SCs. The Co9S8/NS–C material was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). It was found that the Co9S8/NS–C material possessed a unique nanostructure in which Co9S8 NPs were encapsulated in porous graphitic carbon co-doped with N and S. The N/S co-doped porous graphitic carbon of composite led to improved rate performance by enhancing the stability of the electrode material and shortening the ion diffusion paths due to a synergistic effect. The as-prepared Co9S8/NS–C-1.5 h material exhibited a high specific capacitance of 734 F g−1 at a current density of 1 A g−1, excellent rate capability (653 F g−1 at 10 A g−1) and superior cycling stability, i.e., capacitance retention of about 99.8% after 140 000 cycles at a current density of 10 A g−1. Thus, a new approach to fabricate promising electrode materials for high-performance SCs is presented here.

Rational design of N-doped carbon nanobox-supported Fe/Fe2N/Fe3C nanoparticles as efficient oxygen reduction catalysts for Zn–air batteries

Zn–air battery, as a low cost, high energy density, and safe energy device, has received significant attention in recent years. However, its wide application has been hindered due to the low oxygen reduction reaction (ORR) activity in air electrodes without excellent catalysts. Herein, N-doped porous and highly graphitic carbon nanobox-supported Fe-based nanoparticles (Fe–N-CNBs), which were synthesized from fructose, NH3, and FeCl3 by a self-propagating high-temperature synthesis (SHS) process followed by a heat treatment process, were used as ORR catalysts. Fe–N-CNBs calcined at 600 °C (Fe–N-CNBs-600) showed higher ORR activity (onset and half-wave potentials of 1.03 and 0.85 V vs. RHE, respectively), better electrochemical stability, and higher methanol tolerance than Pt/C under alkaline conditions. The outstanding ORR performance of Fe–N-CNBs-600 was attributed to the synergistic effect of Fe, Fe2N, and Fe3C nanoparticles, which was unambiguously confirmed by HRTEM and XRD characterization. Furthermore, Fe–N-CNBs-600 also exhibited higher electrochemical properties than the currently used expensive Pt/C catalyst in Zn–air batteries.

Mesothelin Promotes Invasion and Metastasis in Breast Cancer Cells

Objective: The presence of mesothelin (encoded by the mesothelin [MSLN] gene) in breast cancer is associated with tumour infiltration of the lymph node. This study evaluated whether MSLN overexpression promotes breast cancer cell invasiveness and metastasis. Methods: This study evaluated the effects of overexpression of MSLN on extracellular signal-regulated kinase (ERK1/2) and matrix metalloproteinase (MMP)-9 levels, and the invasiveness and angiogenesis of the breast cancer cell line MCF-7 in vitro, and on MCF-7-derived tumour development in vivo. Results: MSLN overexpression significantly increased ERK1/2 and MMP-9 protein levels and activity, and the invasive and angiogenic capability of MCF-7 cells, in vitro. Inhibition of ERK1/2 suppressed MMP-9 and the invasive and angiogenic capability of MSLN overexpressing MCF-7 cells. MSLN overexpression also increased MCF-7-derived tumour metastasis in vivo. Conclusion: MSLN overexpression promoted the invasive potential of MCF-7 cells through ERK1/2-dependent upregulation of MMP-9; this association may have contributed to metastasis of MCF-7 cells in vivo. Mesothelin may be a useful biomarker for cancer progression and a novel therapeutic or chemopreventive target in human breast cancer.

Construction and validation of master sintering curve for TiO2 for pressureless sintering

Abstract One of the ultimate objectives for sintering research is to predict densification results under different thermal profiles for a given processing method. This paper studies the construction and validation of the master sintering curve (MSC) for rutile TiO2 for pressureless sintering. The MSC was constructed using dilatometry data at two heating rates and was then validated using isothermal holds at three different temperatures. The scanning electron microscopy (SEM) observation shows that the partially sintered samples have the same density under different heating procedures, which demonstrates that the assumptions of the model are reliable. The concept of the MSC could be used to predict the sintering shrinkage and final density and calculate the activation energy. A value of 105 kJ mol-1 for TiO2 was obtained. The MSC could be applied to predict the sintering profile to prepare ceramics with required density and a minimum of grain growth.

Boosting hydrogen evolution via optimized hydrogen adsorption at the interface of CoP3 and Ni2P

Transition metal phosphides (TMPs) have emerged as highly active catalysts for the hydrogen evolution reaction (HER). Herein, we report a novel excellent CoP3/Ni2P catalyst for the HER with a small onset potential of 51 mV vs. RHE, a low Tafel slope of 49 mV dec−1, a small over-potential value of 115 mV at 10 mA cm−2, and outstanding long-term stability. The normalized polarization curve also shows that CoP3/Ni2P has the best intrinsic catalytic activity compared to pure CoP3 and pure Ni2P. Density functional theory (DFT) calculations reveal that the remarkably enhanced catalytic activity is due to the interface effect of CoP3/Ni2P. The strong interactions at the interface can optimize the electronic environment around the active sites, leading to suitable H+ adsorption and H2 formation kinetics and energetics, thereby enhancing the catalytic activity.