| Popis: |
We present realistic molecular models for microporous and templated mesoporous carbons that describe the pore morphology and topology in a realistic way. In our work on modeling microporous carbons, we have developed a Hybrid Reverse Monte Carlo method to build molecular models that match the structural data obtained from experiments and capture the correct chemisty of the carbon atoms at the local level. Our method is based on Reverse Monte Carlo with an additional energy penalty term. The presence of the energy penalty term reduces the probability of having unrealistic features such as 3 and 4 member rings, reported in many previous Reverse Monte Carlo studies of carbons, in the resultant models. Hydrogen atoms, which are normally ignored or implicitly assumed in most of the simulation studies of porous carbons, are explicitly taken into account in our method. We built models for 3 saccharose based carbons and using a ring connectivity method, that we developed, we found that the resultant models contain highly defective and convoluted graphene segments. We also simulated adsorption of argon using grand canonical Monte Carlo simulations. The simulated isosteric heats of adsorption are in good agreement with experimental results. Our results show that the inclusion of explicit hydrogen atoms in the model is necessary to reproduce the local structure and adsorption properties of real carbons. In the second part of our project, we have used pseudo mimetic methods to develop molecular models for 3 silica templated mesoporous carbons: CMK-1, CMK-3 and CMK-5. These models include pore surface roughness and morphological defects found in real materials. We performed GCMC simulation of argon at 77K and found that the shape of the experimental adsorption isotherms is reproduced well by our mesoporous carbon models. |
