Lizeng Zuo

Biomass-Derived Nitrogen-Doped Carbon Nanofiber Network: A Facile Template for Decoration of Ultrathin Nickel-Cobalt Layered Double Hydroxide Nanosheets as High-Performance Asymmetric Supercapacitor Electrode.

The development of biomass-based energy storage devices is an emerging trend to reduce the ever-increasing consumption of non-renewable resources. Here, nitrogen-doped carbonized bacterial cellulose (CBC-N) nanofibers are obtained by one-step carbonization of polyaniline coated bacterial cellulose (BC) nanofibers, which not only display excellent capacitive performance as the supercapacitor electrode, but also act as 3D bio-template for further deposition of ultrathin nickel-cobalt layered double hydroxide (Ni-Co LDH) nanosheets. The as-obtained CBC-N@LDH composite electrodes exhibit significantly enhanced specific capacitance (1949.5 F g(-1) at a discharge current density of 1 A g(-1) , based on active materials), high capacitance retention of 54.7% even at a high discharge current density of 10 A g(-1) and excellent cycling stability of 74.4% retention after 5000 cycles. Furthermore, asymmetric supercapacitors (ASCs) are constructed using CBC-N@LDH composites as positive electrode materials and CBC-N nanofibers as negative electrode materials. By virtue of the intrinsic pseudocapacitive characteristics of CBC-N@LDH composites and 3D nitrogen-doped carbon nanofiber networks, the developed ASC exhibits high energy density of 36.3 Wh kg(-1) at the power density of 800.2 W kg(-1) . Therefore, this work presents a novel protocol for the large-scale production of biomass-derived high-performance electrode materials in practical supercapacitor applications.

Cotton Wool Derived Carbon Fiber Aerogel Supported Few-Layered MoSe2 Nanosheets As Efficient Electrocatalysts for Hydrogen Evolution

Recent studies have proven that newly emerging two-dimensional molybdenum diselenide (MoSe2) is a promising noble-metal-free electrocatalyst for hydrogen evolution reaction (HER). Increasing the exposures of the active edges of MoSe2 nanostructures is a key issue to fully realize the excellent electrochemical properties of MoSe2. In this work, a few-layered MoSe2/carbon fiber aerogel (CFA) hybrids have been facilely obtained through the combination of high-temperature carbonization and one-pot solvothermal reaction. CFA derived from cotton wool is used as a three-dimensional conductive network for construction of hierarchical MoSe2/CFA hybrids, where few-layered MoSe2 nanosheets are uniformly and perpendicularly decorated on the surfaces of CFA. In the designed and prepared hybrids, CFA effectively increases the exposures of the active edges of MoSe2 nanosheets as well as provides reduced lengths for both electron transportation and ion diffusion. Therefore, the obtained optimal MoSe2/CFA hybrid exhibits excellent electrochemical activity as HER electrocatalyst with a small onset potential of -0.104 V vs reversible hydrogen electrode and a small Tafel slope of 62 mV per decade, showing its great potential as a next-generation Pt-free electrocatalyst for HER.

Immobilization of NiS nanoparticles on N-doped carbon fiber aerogels as advanced electrode materials for supercapacitors

NiS nanoparticles (NPs) with excellent electrochemical capacitance have attracted considerable attention as cost-effective energy-storage materials for supercapacitors in recent years. Preventing the aggregation and increasing the conductivity of NiS NPs are key to fully realizing their excellent electrochemical properties. In this work, NiS/N-doped carbon fiber aerogel (N-CFA) nanocomposites were obtained easily through the combination of polymerization, carbonization, and a one-step solvothermal reaction. N-CFA derived from polydopamine (PDA)-coated cotton wool was used as a template for the construction of hierarchical NiS/N-CFA nanocomposites, in which NiS NPs are uniformly immobilized on the surface of N-CFA. In this nanostructured system, N-CFA containing abundant nanofibers not only provides active regions for the growth of NiS NPs to prevent their aggregation, but also offers short pathways for the transport of electrons and ions. The electrochemical properties of the obtained NiS/N-CFA nanocomposites were investigated by cyclic voltammetry, galvanostatic charge–discharge, and alternating current impedance measurements. The optimized NiS/N-CFA nanocomposite exhibits a high specific capacitance of 1,612.5 F·g‒1 at a charge/discharge current density of 1 A·g‒1 and excellent rate capacitance retention of 66.7% at 20 A·g‒1. The excellent electrochemical properties of NiS/N-CFA nanocomposites make these materials promising electrode materials for supercapacitors.

Polymer/Carbon-Based Hybrid Aerogels: Preparation, Properties and Applications

Aerogels are synthetic porous materials derived from sol-gel materials in which the liquid component has been replaced with gas to leave intact solid nanostructures without pore collapse. Recently, aerogels based on natural or synthetic polymers, called polymer or organic aerogels, have been widely explored due to their porous structures and unique properties, such as high specific surface area, low density, low thermal conductivity and dielectric constant. This paper gives a comprehensive review about the most recent progresses in preparation, structures and properties of polymer and their derived carbon-based aerogels, as well as their potential applications in various fields including energy storage, adsorption, thermal insulation and flame retardancy. To facilitate further research and development, the technical challenges are discussed, and several future research directions are also suggested in this review.

Electrospun nanofiber-supported carbon aerogel as a versatile platform toward asymmetric supercapacitors

As a novel kind of carbon-based material, carbon aerogels have attracted widespread attention owing to their integrated properties of a large internal surface area, small pore size, and outstanding mechanical strength. In this study, a fascinating carbon aerogel has been rationally designed with a unique cellular structure, consisting of one-dimensional carbon nanofibers derived from oxidized polyacrylonitrile (o-PAN) and two-dimensional carbon sheets originating from polyimide (PI). The interconnected o-PAN/PI (oPP) carbon aerogel exhibits low density but increased mechanical strength and can not only act as a versatile adsorbent but also as an ideal template for the in situ growth of MnO2 nanosheets to obtain oPP@MnO2 hybrid carbon aerogel. The oPP@MnO2 composite aerogel exhibits extraordinary electrochemical characteristics with a maximum specific capacitance of 1066 F g−1, approaching the theoretical value (1370 F g−1) of MnO2. Moreover, an assembled oPP@MnO2//activated oPP (A-oPP) asymmetric supercapacitor delivers a considerably high energy density of up to 30.3 W h kg−1, highlighting the advantages of the unique cellular structure of the oPP carbon aerogel and oPP@MnO2 hybrid carbon aerogel. Therefore, the successful fabrication of the oPP carbon aerogel widens the scope of traditional electrospun lamellar membranes to multi-dimensional aerogels, providing a new strategy for the construction of nanofiber-based materials for energy storage and environmental protection applications.

Electrospun carbon nanofiber@CoS2 core/sheath hybrid as an efficient all-pH hydrogen evolution electrocatalyst

Developing all-pH and efficient non-noble-metal electrocatalysts for the hydrogen evolution reaction (HER) remains a great challenge in science nowadays. In this work, carbon nanofiber (CNF)@CoS2 hybrids with a hierarchical core/sheath structure have been successfully fabricated via a combination of electrospinning and hydrothermal methods for use as HER electrocatalysts under all-pH media. The CoS2 nanoparticles are uniformly attached onto the three-dimensional (3D) CNF framework, and have different morphologies on adjusting the concentration of the Co and S precursors. This shows that the morphology of the electrocatalytically active CoS2 has a great impact on the HER performance, which can be attributed to the difference in the exposure of the effective catalytic sites. Moreover, the CNF@CoS2 hybrids distinctly exhibit superior HER activities compared to that of pure CoS2 agglomerates, which highlights the importance of the 3D carrier with a nanostructure to increase the number of exposed electrocatalytic sites. When applied as electrocatalysts operating at all-pH values, the CNF@CoS2 hybrids exhibit remarkable HER properties, with a low onset potential of −40 mV, a small Tafel slope of 66.8 mV per decade and a large current density (10.0 mA cm−2 at η = 110 mV) in acid medium, along with a low onset potential of −130 mV in both alkaline and neutral conditions. Apart from the facile preparation of an efficient all-pH electrocatalyst, this work highlights the impacts of morphology and nanostructure of the catalyst on the HER activity, which is universally applicable in the field of catalysis.