Preparation And Application Of Nitrogen-doped Composite Carbon Materials Derived From MOFs

Metal-organic Frameworks?MOFs?,also known as Porous Coordination Polymers?PCPs?or Metal-organic Materials?MOMs?,are a class of highly ordered porous crystalline materials that are self-assembled by metal ions or their metal clusters and the functional groups of carboxylate or imidazolate ligands through flexible and diverse coordinate bonds.With unique physical properties such as order and variable structure,MOFs materials are widely used in many fields such as gas storage and separation,catalysis,guest molecular recognition and drug delivery,energy storage and conversion.In recent years,MOFs with regular morphology can derive carbon materials modified with highly active atoms?B,N,S,P,Fe,Ni,Co,etc.?.In particular,the carbon materials derived from MOFs have obvious advantages as electrode materials.The annealing treatment of MOFs at high temperature can partially retain the long-range order and high porosity of MOFs,and can provide a high surface area of the resulting porous carbon.Meanwhile,many carbon nanotubes and highly active catalysts are grown through high-temperature catalytic growth.In this paper,we mainly discuss the rational design and growth of a variety of porous MOFs materials through simple solvothermal reactions,and pyrolysis at high temperature to derive nitrogen-doped composite carbon materials.In addition,it is studied in electrocatalysis applications.The content of the thesis is divided into the following chapters:?1?We have successfully synthesized unique hollow N-doped carbon spheres?HNCSs?from an initial amorphous coordination polymer?Zn-BTC microspheres?template by a bottom-up approach.The prepared HNCSs exhibits excellent ORR electrocatalytic activity and stability,mainly due to the elaborately constructed hollow morphology with nanosized thin shells,graphitized carbon skeleton,large porosity,and specific surface area,which promotes the highest density of catalytic active sites.Therefore,the present findings provide a promising synthetic strategy from designed MOF-based core-shell composites to hollow carbon nanostructures as highly efficient electrocatalysts for ORR.?2?Using MOF-assisted self-sacrificial template method,Mo₂C nanoparticles are successfully implanted into hollow N-doped carbon polyhedrons?Mo₂C@HNCPs?to obtain the highly active HER catalyst.The experimental results showcase that due to the synergistic effect of the hollow morphology,the high active sites of Mo₂C nanoparticles and rich nitrogen atoms,and the rich active sites on the heterostructure,the material exhibits highly efficient HER activity.The study indicates the direction in which is provided the design of highly dispersed and ultrafine transition metal carbide-based HER electrocatalysts.?3?We have reported that the Co-based coordination polymer?ZIF-67?anchoring on an indium-organic framework?In OF-1?composites?In OF-1@ZIF-67?are treated followed by carbonization and phosphorization to successfully obtain Co P nanoparticles embedded carbon nanotubes and nitrogen-doped carbon materials?Co P-In NC@CNT?.The bimetallic MOF-derived Co P-In NC@CNT material can not only act as a high-performance over water splitting?OWS?catalyst but also initiate a strategy to synthesize Co P-loaded nitrogen-doped carbon composite with fine structure.Furthermore,the present work can be readily extended to offer the cost-effective,energy-efficient,and bifunctional electrocatalysts of metal phosphide electrodes.