Preparation Of Biomass-Based Carbon And Carbon-Silicon Composites And Their Catalytic And Energy Storage Properties

With the rapid development of the economy and society,energy and environmental issues have received widespread attention worldwide.Rice husk biomass is a widely distributed and easily recyclable low-cost renewable carbon source.Its reasonable utilization can not only avoid environmental problems caused by incineration,but also provide huge economic benefits.Therefore,multifunctional carbon materials prepared from rice husks have broad application prospects.This paper prepared various rice husk based carbon and carbon silicon composite materials using rice husks as raw materials,and tested their catalytic and energy storage properties.The main research content is as follows:1.Fabrication heterogeneous structures with tunable surface wettability via renewable methods have important research significance for biphasic interface catalysis.In this work,carbon-coated silica core-shell microspheres（Si O₂@C）were prepared from biomass waste rice husks via a facile in situ self-assembly method.The wettability of Si O₂@C could be facilely tuned by adjusting the titration end point in the self-assembly process,i.e.adjusting the mass ratio of C to Si O₂.The prepared Si O₂@C supported Ru catalysts（Ru/Si O₂@C）can be used for vanillin hydrodeoxygenation reaction both in Pickering emulsions and aqueous phase systems.For the water-oil biphasic reaction,the wettability of catalysts plays a key role in the formation of Pickering emulsions,and the prepared Ru/Si O₂@C-5-A catalyst with amphiphilicity property achieves excellent catalytic activity and p-creosol selectivity（>99%）in both W/O and O/W Pickering emulsions.For the aqueous phase reaction,the higher the hydrophilicity of catalyst,the higher activity it is for the hydrodeoxygenation of vanillin.Meanwhile,the catalyst has good recyclability.2.With the increasing concern of energy and environmental issues,the efficient conversion of biomass into liquid fuels and functional materials has important significance.In this work,we conducted thermo-chemistry transformation of low-cost and sustainable biomass waste rice husks to prepare high nitrogen-doped biochar（CN）.Owing to the rich N content,Pd nanoparticles can be uniformly dispersed on the surface of biochar skeleton with natural network structures,forming a highly active,selective,stable,and recyclable Pd/CN catalysts for the hydrodeoxygenation of vanillin to p-creosol under mild conditions（0.8 MPa,80°C,1 h）.The TOF value reaches 974 h^-1.The catalyst exhibits excellent cycling stability,after three recycles,the selectivity of p-creosol only decreases by 6.2%.Possible reaction pathways of vanillin hydrodeoxygenation over Pd/CN in Pickering emulsions are proposed.3.Here,we report a hierarchical porous carbon network derived from rice husk biomass and extended its application to supercapacitors and efficient OER electrocatalysts.Homogeneous incorporation of nitrogen atoms into the carbon skeleton can provide more active site for OER reaction,improve the conductivity and wettability of carbon materials and generate pseudo capacitance,thus improving the electric double-layer capacitance of the electrode.The nitrogen doped porous carbon prepared at 800 ^oC（RCN₇-800）exhibits a low OER overpotential of 334 m V（vs.reversible hydrogen electrode）at 10 m A cm^-2 and small tafel slope(80.4 m V dec^-1).In addition,RHPCN₅ exhibits excellent capacitance performance,with a specific capacitance of 203 F g^-1 at a current density of 0.5 A g^-1.The prepared supercapacitor has good cycling stability,with a capacitance retention rate of about 100%after 20000cycles.