Controllable Preparation Of Hollow Structured Mesoporous Carbon And Its Electrocatalytic Oxygen Evolution Performance

How to design and prepare ordered mesoporous materials with high exposed surface area and provide more active sites and fast ion diffusion channels is of great significance to solve the challenges of electrochemical-related applications such as accelerated oxygen evolution reaction（OER）.Mesoporous carbon materials have broad application prospects in energy storage,catalysis and sensors based on their uniform and adjustable size and specific surface area.However,preparing mesoporous carbon materials with high exposed surface areas is extremely challenging because most materials have dimensional defects（large size,irregular shape）that limit the mass transfer and charge transfer in OER reaction.Therefore,developing a simple and general method to synthesize mesoporous carbon with high accessible surface area is a challenge that must be overcome.Metal organic frameworks（MOFs）are a kind of hollow materials with adjustable components and functions.Such as ZIF（Zeolitic Imidazolate Framework）nanosheets,pseudonanosheets or nanoplates with high aspect ratio,which are favored by researchers due to their unique structure,electrical and optical properties.Therefore,MOF materials can be used to design hollow carbon with ordered mesoporous structure,which is expected to become an ideal material to improve electrochemical properties.We adopted a self-templating method to prepare hollow structured mesoporous carbon（HOMC）nanoplates.Firstly,leaf like ZIF（ZIF-L）nanoplates are prepared,and then triblock copolymer Pluronic F127 is used as a soft template,and phenolic resin（Resol）is used as a nitrogen source to form ordered mesoscopic composite micelles.The micelles are deposited and polymerized on the surface of ZIF-L through solution synergistic induced self-assembly.After the hydrothermal reaction,ordered mesoporous hollow structure polymers with uniform 2～8 nm mesoporous were formed.Further,nitrogen-doped carbon materials were obtained by pyrolysis in inert gas.The carbonized HOMC nanosheets have uniform mesoporous.The ordered mesoporous hollow carbon materials were used as electrocatalysts for OER reaction,which effectively promoted the diffusion of ions in two-dimensional material space and achieved better OER performance.Therefore,this paper mainly includes the following research:First,controllable preparation of hollow mesoporous carbon nanoplates named HOMC.ZIF-L was prepared by wet chemical method;Then,ordered mesoscopic complex micelles were synthesized by solvent induced organic-organic self-assembly,that is,polymer block copolymer Resol-F127 micelles.The polymer micelle coating of ZIF-L was realized through the polycondensation reaction induced by the liquid phase interface.Then the formed resol was coated Resol-F127@ZIF-L nanostructures were subjected to hydrothermal treatment further to promote the crosslinking and curing of micelles and nanoplants.After that,Resol-F127@ZIF-L was pyrolyzed and carbonized to form a composite porous nitrogen-doped carbon composite electrode material named HOMC.HOMC was used as OER reaction electrocatalyst to study the electrochemical performance.Second,FeCl₃was added into the ZIF-L and Resol-F127 micelles hydrothermal reaction to obtain Fe doped HOMC.The experiment shows that the best OER performance is obtained when the doping mass of the Fe atom is 0.75%of the total mass of Resol-F127@ZIF-L（Fe0.75/HOMC）.In order to further optimize its electrocatalytic performance,the OER test of Fe_0.75P/HOMC shows that when the current density was 10 m A cm^-2,the overpotential of the sample was 285 m V.When the current density was 50 m A cm^-2,the overpotential was only 338 m V,which is better than commercial electrocatalyst Ru O₂.In addition,Fe_0.75P/HOMC showed excellent electrochemical stability(at least 40 h at 10 m A cm^-2).In this paper,the hollow structured mesoporous carbon designed and prepared by MOF material has excellent OER performance and durability and is expected to be an ideal choice for improving electrochemical performance.