Feili Lai

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.

Nitrogen-Doped Carbon Nanofiber/Molybdenum Disulfide Nanocomposites Derived from Bacterial Cellulose for High-Efficiency Electrocatalytic Hydrogen Evolution Reaction

To remit energy crisis and environmental deterioration, non-noble metal nanocomposites have attracted extensive attention, acting as a fresh kind of cost-effective electrocatalysts for hydrogen evolution reaction (HER). In this work, hierarchically organized nitrogen-doped carbon nanofiber/molybdenum disulfide (pBC-N/MoS2) nanocomposites were successfully prepared via the combination of in situ polymerization, high-temperature carbonization process, and hydrothermal reaction. Attributing to the uniform coating of polyaniline on the surface of bacterial cellulose, the nitrogen-doped carbon nanofiber network acts as an excellent three-dimensional template for hydrothermal growth of MoS2 nanosheets. The obtained hierarchical pBC-N/MoS2 nanocomposites exhibit excellent electrocatalytic activity for HER with small overpotential of 108 mV, high current density of 8.7 mA cm(-2) at η = 200 mV, low Tafel slope of 61 mV dec(-1), and even excellent stability. The greatly improved performance is benefiting from the highly exposed active edge sites of MoS2 nanosheets, the intimate connection between MoS2 nanosheets and the highly conductive nitrogen-doped carbon nanofibers and the three-dimensional networks thus formed. Therefore, this work provides a novel strategy for design and application of bacterial cellulose and MoS2-based nanocomposites as cost-effective HER eletrocatalysts.

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.

Bionanofiber Assisted Decoration of Few‐Layered MoSe2 Nanosheets on 3D Conductive Networks for Efficient Hydrogen Evolution

Molybdenum diselenide (MoSe2 ) has emerged as a promising electrocatalyst for hydrogen evolution reaction (HER). However, its properties are still confined due to the limited active sites and poor conductivity. Thus, it remains a great challenge to synergistically achieve structural and electronic modulations for MoSe2 -based HER catalysts because of the contradictory relationship between these two characteristics. Herein, bacterial cellulose-derived carbon nanofibers are used to assist the uniform growth of few-layered MoSe2 nanosheets, which effectively increase the active sites of MoSe2 for hydrogen atom adsorption. Meanwhile, carbonized bacterial cellulose (CBC) nanofibers provide a 3D network for electrolyte penetration into the inner space and accelerate electron transfer as well, thus leading to the dramatically increased HER activity. In acidic media, the CBC/MoSe2 hybrid catalyst exhibits fast hydrogen evolution kinetics with onset overpotential of 91 mV and Tafel slope of 55 mV dec-1 , which is much more outstanding than both bulk MoSe2 aggregates and CBC nanofibers. Furthermore, the fast HER kinetics are well supported by theoretical calculations of density-functional-theory analysis with a low activation barrier of 0.08 eV for H2 generation. Hence, this work highlights an efficient solution to develop high-performance HER catalysts by incorporating biotemplate materials, to simultaneously achieve increased active sites and conductivity.

Elastic Carbon Aerogels Reconstructed from Electrospun Nanofibers and Graphene as Three-Dimensional Networked Matrix for Efficient Energy Storage/Conversion

Three-dimensional (3D) all-carbon nanofibrous aerogels with good structural stability and elasticity are highly desirable in flexible energy storage/conversion devices. Hence, an efficient surface-induced co-assembly strategy is reported for the novel design and reconstruction of electrospun nanofibers into graphene/carbon nanofiber (CNF) composite aerogels (GCA) with hierarchical structures utilizing graphene flakes as cross-linkers. The as-obtained GCA monoliths possess interconnected macropores and integrated conductive networks, which exhibit high elasticity and great structural robustness. Benefitting from the largely increased surface area and charge-transfer efficiency derived from the multi-form firm interconnections (including pillaring, bridging and jointing) between graphene flakes and CNF ribs, GCA not only reveals prominent capacitive performance as supercapacitor electrode, but also shows excellent hydrogen evolution reaction activity in both acidic and alkaline solutions as a 3D template for decoration of few-layered MoSe2 nanosheets, holding great potentials for energy-related applications.

A highly flexible and conductive graphene-wrapped carbon nanofiber membrane for high-performance electrocatalytic applications

The integration of conventional carbonaceous materials with advanced two-dimensional graphene is a challenging but worthwhile attempt to introduce innovative properties into new composites. Herein, we report a novel and facile strategy to create graphene wrapped electrospun carbon nanofiber (GwC) membranes through the surface-induced assembly of graphene oxide (GO) on the surface of pre-oxidized electrospun PAN (oPAN) nanofibers and subsequent carbonization. Driven by the hydrogen bonding between oxygen-containing groups of GO and tertiary amino groups of oPAN, GwC composite membranes with significantly reinforced electrical conductivity are obtained in which every single oPAN fiber is tightly and evenly wrapped by graphene sheets. Additionally, the GwC membrane is further considered as a free-standing template for an in situ growth of few-layered MoSe2 nanosheets. Compared with the graphene-free counterparts, GwC–MoSe2 composites exhibit a superior electrochemical hydrogen evolution reaction (HER) performance in both acidic and alkaline solutions due to the highly conductive GwC backbone, thus endowing the newly designed GwC membranes with various possibilities for applications in energy-related fields.