Grand canonical Monte Carlo simulation study of hydrogen storage by Li-decorated pha-graphene

Grand canonical Monte Carlo simulation(GCMCs)is utilized for studying hydrogen storage gravimetric density by pha-graphene at different metal densities,temperatures and pressures.It is demonstrated that the optimum adsorbent location for Li atoms is the center of the seven-membered ring of pha-graphene.The binding energy of Li-decorated phagraphene is larger than the cohesive energy of Li atoms,implying that Li can be distributed on the surface of pha-graphene without forming metal clusters.We fitted the force field parameters of Li and C atoms at different positions and performed GCMCs to study the absorption capacity of H_(2).The capacity of hydrogen storage was studied by the differing density of Li decoration.The maximum hydrogen storage capacity of 4Li-decorated pha-graphene was 15.88 wt%at 77 K and100 bar.The enthalpy values of adsorption at the three densities are in the ideal range of 15 kJ·mol^(-1)-25 kJ·mol^(-1).The GCMC results at different pressures and temperatures show that with the increase in Li decorative density,the hydrogen storage gravimetric ratio of pha-graphene decreases but can reach the 2025 US Department of Energy's standard(5.5 wt%).Therefore,pha-graphene is considered to be a potential hydrogen storage material.

Zeolite-templated carbons as effective sorbents to remove methylsiloxanes and derivatives:A computational screening

Though widely used in our daily lives,volatile methylsiloxanes and derivatives are emerging contaminants and becoming a high-priority environment and public health concern.Developing effective sorbent materials can remove siloxanes in a cost-effective manner.Herein,by means of Grand Canonical Monte Carlo(GCMC)simulations,we evaluated the potentials of the recently proposed 68 stable zeolite-templated carbons(ZTCs)(PNAS 2018,115,E8116-E8124)for the removal of four linear methylsiloxanes and derivatives as well as two cyclic methylsiloxanes by the calculated average loading and average adsorption energy values.Four ZTCs,namely ISV,FAU1,FAU3,and H8326836,were identified with the top 50%adsorption performance toward all the six targeted contaminants,which outperform activated carbons.Further first principles computations revealed that steric hindrance,electrostatic interactions(further enhanced by charge transfer),and CH-p interactions account for the outstanding adsorption performance of these ZTCs.This work provides a quick procedure to computationally screen promising ZTCs for siloxane removal,and help guide future experimental and theoretical investigations.