Preparation And Application Of Functional Ordered Mesoporous Carbon

Ordered mesoporous carbon (OMC), as a new type of porous material, has been widely used in catalysis, adsorption, sensors, energy storage and lithium battery and so on, because of its high specific surface area, uniform pore size, excellent hydrothermal stability and conductivity. It has attracted great research interest and found many applications. The heterogeneous doping and metallic particle decoration on OMC can greatly improve the properties. The research of OMC-based composites in this paper mainly related to the adsorption and electrochemical hydrogen storage fields. Material design, preparation, characterization and theoretical analysis are carried out in the paper. The main contents are summarized as follows:1. Mesoporous nitrogen-doped carbon (MCN) with tailored structure and high nitrogen content were synthesized using hydrolysis method. The MCN with tailored textures and adjustable nitrogen content were synthesized using SBA-15 as a hard template, diaminobenzene (DAB) and ammonium peroxydisulfate (APDS) as carbon and nitrogen sources by adjusting the synthesis temperature and precursor ratio. By adjusting the synthesis temperatures in a range of 70-100℃, the pore diameter of the MCN materials can be tuned from 3.43 to 4.15 nm, while the specific surface area of the MCN with a nitrogen content of 26.5 wt.%, can be tuned from 281.8 to 535.2m2/g. The C/N molar ratio of the MCN can be tuned in a range of 3.25-3.65 by adjusting the mole ratio of DAB/APDS precursors at a synthesis temperature of 80℃, while the pore diameter of the MCN be tuned in a range of 4.12-3.66 nm. It is indicated that well ordered MCN materials with large specific surface area, high total pore volume and high nitrogen content can be fabricated under a synthesis temperature of 80℃and a molar ratio of 1.5 for DAB/APDS precursors.2. The composite magnetic adsorbents were prepared by a two-step method. The magnetic structured Ni-OMCs samples with Ni nanoparticles homogeneously decorated were synthesized via high temperature calcination route using OMC as matrix, Ni(CH3COO)2·4H2O as nickel source. The size of Ni particles can be controlled to be less than 10nm. The effects of several important parameters such as contact time, temperature, adsorbent dosage and adsorbate concentration on the absorption capabilities were studied in detail. The results show that the adsorption capacities for MO on the OMCs and Ni-OMCs adsorbents could be well described according to Langmuir isotherm with MO molecule preferentially adsorbed in the structured mesopores, and the adsorption capacities was almost 3 times compared with active carbon powers. The characterization by magnetic hysteresis loops suggests a ferromagnetic behavior for the Ni-OMCs samples with a magnetization saturation of 2.34 emu/g at 300 K, high enough for external applied magnet separation.3. The PtRu alloyed particle decorated OMC materials for electrochemical hydrogen storage were prepared using two-step method. The OMC/PtRu composite were synthesized using OMC as a matrix, RuCl3·xH2O and H2PtCl6·6H2O as ruthenium and platinum sources and ethylene glycol (EG) as reducing agent. PtRu alloyed nanoparticles with an average diameter of 3.6 nm were well decorated homogeneously both on the exterior surfaces and interior channels of the OMC matrix. The electrochemical hydrogen storage capacities of OMC/PtRu, OMC/Pt and OMC are comparatively investigated using cyclic voltammetry and galvanostatic charge-discharge techniques. It is revealed that the PtRu nanoparticle modified OMC samples display an enhanced electrochemical hydrogen storage capacity of 411.8 mAh/g, almost 2.3 times higher than pure OMC electrode and 1.5 times higher than monometallic OMC/Pt electrode.