Investigation On Preparation And Catalytic Application Of Lignocellulose Nanocomposite Materials

Excessive consumption of nonrenewable fossil fuels has caused serious energy and environmental issues.The amount of annual agricultural and forestry waste is up to 7 hundred million tons in China.Effectively converting lignocellulosic resources into valuable energy,chemicals and novel materials has very important significance for realizing the sustainable development.Accordingly,using lignocellulosic biomass to replace fossil fuels applied in energy,chemical and material fields has drawn worldwide attention.In order to utilize these lignocellulosic resources,a series of researches was carried out to develop lignocellulose nanocomposite catalytic materials in this study.（1）Electrospun cellulose acetate（CA）membrane was employed as a support that provided sites for AgCl crystals in-stu growth.The Ag@AgCl crystals on electrospun CA composites with exposed{100}and{111}facets were fabricated at room temperture by a double diffusion technique.The crystal structure,morphology,composition,valence,and absorption light ability etc.of CA supported Ag@AgCl were characterized.The results show that the loading of AgCl crystals can reach 60%（w/w）.The photocatalytic activity of the catalysts was evaluated using Methyl orange（MO）as a target.The CA supported cubic Ag@AgCl catalyst exhibited much higher catalytic activity than octahedral catalyst in terms of the degradation of MO under visible light.The 10 mg CA based cubes could completely degrade MO(10 mg L^-1)in 160 min.The photocatalyst still exhibited a good catalytic ability after three times.（2）The lignin,a special three-dimensional molecular was successfully processed into uniform nanosphere under electrospraying conditions.The lignin nanosphere was further applied as a sustainable support for preparing cuprous oxide（Cu₂O）biocatalyst.The unique composite structure favoured a Huisgen[3+2]cycloaddition reaction.Triazoles synthesis had a highest 99%yield under solvent-free conditions with the catalyst.As compared with other copper mediated“Click”reactions,it showed a higher yield（up to 99%）,and required shorter reaction time and relatively milder conditions to synthesize 1,2,3-triazoles.（3）Waste fibers have been utilized as support to synthesize monodispersed Ag/C composites.Utilizing a facile carbonization process,the fibers were converted to carbon with embedded mesoporous structures.Through the one-step thermal reduction and carbonization,a meso-pore carbon frame with mono-dispersed silver nanoparticles（Ag/C）were conveniently synthesized.The Ag/C showed excellent catalytic activity in 4-nitrophenol reduction reactions.It could be recycled for ten times without significant loss of catalytic activity.In addition,the Ag/C could be used as a Surface-enhanced Raman Scattering（SERS）substrate,and the SERS signals strength were shown to be seven times higher than the unloaded carbon membrane.The results clearly indicated that the Ag nanoparticles loaded paper substrate exhibited SERS activity with homogeneous signals,rendering it an excellent SERS substrate for practical applications.（4）A renewable and facile route to prepare alkali lignin based carbon nanofiber mats as lithium battery cathode materials using a conventional electrospinning technique and preoxidation carbonization process has been developed.The features of low-cost,abundant and aromatic,heterogeneous bio-macromolecule of lignin make it suitable as a carbon precursor.The results showed that lignin-derived fibers exhibited the best electrochemical properties and lowest electrical resistance at 900 ^℃ carbonization.The lithium battery still had a specific capacitance of 230.8 mA g^-1 after 1000 charge and discharge cycles.The study demonstrated that the lignin which was always as a paper industry by-product could be utilized as a promising precursor to prepare high-performance and low-cost carbon fibrous electrode materials for applications in energy storage systems.（5）The hemicellulose-based composite nanofiber membrane material was prepared by electrospinning technology.The nitrogen-doped hemicelluloses/PAN derived carbon nanocomposite catalyst was further successfully prepared.The nitrogen-doped hemicelluloses/PAN carbon fiber catalytic material of 700 ^℃ showed a super ORR performance,including an identical onset,comparable electron transfer number as compared with that of commercial Pt/C catalyst.Besides,the catalyst exhibited good working stability and tolerance to fuel crossover effects.The work provided a way to utilize aboudant and inexpensive hemicellulose as precursor to fabricate carbon materials for high-performance oxygen reduction catalytic materials.