The Design And Synthesis Of Carbon-based Composites And Their Application In Energy Storage And Hydrogen Evolution Reactions

Porous carbon materials are widely used in electrochemistry due to their high specific surface area,good electrical conductivity,variable pore structure,and surface properties.First of all,advanced carbon materials can be used as energy storage materials with the high power density and high cycle stability;second,through the combination of carbon materials and metal oxides,the limitation of low theoretical specific capacity(372mAh g^-1)of traditional commercial graphite electrode materials in lithium batteries can be broken,and the energy density of lithium-ion batteries will be improved;third,carbon materials can be used as a carrier to load non-noble metal catalysts so that it can provide a solution for the replacement of expensive Pt/C catalysts for hydrogen production.In the above applications,the structural adjustment,surface modification,and morphology control of carbon-based?composite?materials play a vital role in improving electrochemistry performance.This paper focuses on the design and construction of new carbon-based?composite?materials and strives to achieve the application of high-efficiency energy storage and electrocatalytic hydrogen production.At the same time,we through the study of the structure-effect relationship of the system and explains its efficiency-enhancing mechanism to provide theoretical guidance for the rational preparation of porous carbon materials.?1?Functional carbon materials with nitrogen-doped surface and three-dimensional hierarchical porous structure were prepared by template method and in situ chemical activation method using almond as precursor.When used as a supercapacitor energy storage material,the best almond-derived carbon?Alm-P-K-800?exhibits excellent capacitance performance and rate performance,at a current density of 1.0 A g^-1,the specific capacitance is 228 F g^-1.This can be attributed to the high specific surface area of the material(1877.8 m² g^-1),macropore-mesopore-micropore grade pore structure,and nitrogen-doped and oxygen-functionalized carbon surface.?2?Highly dispersed MoO_x nanoparticles anchored on nitrogen-doped three-dimensional porous carbon?3D-MoO_x@CN?were prepared by template method and in situ complexation strategy.The particle size of MoO_x nanoparticles is approximately1.5 nm to 3.5 nm,and the porous carbon materials exhibit a macropore-mesopore-micropore grade pore structure.When used as an anode electrode of lithium-ion batteries,the 3D-MoO_x@CN composite material exhibits a high specific capacity(at a current density of 0.1 A g^-1 and 1.0 A g^-1,the specific capacity is 742 mAh g^-1 and 431 mAh g^-1,respectively.),faster charge transfer kinetics and good cycle stability.Its excellent performance can be attributed to the synergistic effect of MoO_x and porous nitrogen-doped carbon,ultra-dispersed MoO_x exposes higher electrochemical surface area,and the surface of nitrogen-doped carbon can improve the electrical conductivity,the three-dimensional pore structure can promote Li⁺transmission.At the same time,the strong binding force between the surface of the carbon material and MoO_x nanoparticles can effectively inhibit the volume expansion of MoO_x nanoparticles during charge and discharge.?3?Hollow nano CoP composites loaded with graphene with high surface area were successfully prepared.The high specific surface of graphene can achieve anchoring and high dispersion of CoP nanoparticles.Due to the Kirkendall effect,CoP eventually forms a hollow structure.In the prepared composite material?H-CoP@RGO?,the particle size of CoP is about 10-20 nm,and the thickness of the shell is 2-4 nm.Because of its unique high dispersion and hollow structure,CoP is beneficial to expose more active sites,and graphene provides a guarantee for high conductivity of the material.When used as a catalyst for the hydrogen evolution reaction of water splitting,the composite material exhibits excellent catalytic activity and stability.