Towards Performant Design of Carbon-Based Nanomotors for Hydrogen Separation through Molecular Dynamics Simulations

Clean energy technologies represent a hot topic for research communities worldwide. Hydrogen fuel, a prized alternative to fossil fuels, displays weaknesses such as the poisoning by impurities of the precious metal catalyst which controls the reaction involved in its production. Thus, separating H₂ out of the other gases, meaning CH₄, CO, CO₂, N₂, and H₂O is essential. We present a rotating partially double-walled carbon nanotube membrane design for hydrogen separation and evaluate its performance using molecular dynamics simulations by imposing three discrete angular velocities. We provide a nano-perspective of the gas behaviors inside the membrane and extract key insights from the filtration process, pore placement, flux, and permeance of the membrane. We display a very high selectivity case (ω = 180° ps^-1) and show that the outcome of Molecular Dynamics (MD) simulations can be both intuitive and counter-intuitive when increasing the ω parameter (ω = 270° ps^-1; ω = 360° ps^-1). Thus, in the highly selective, ω = 180° ps^-1, only H₂ molecules and 1-2 H₂O molecules pass into the filtrate area. In the ω = 270° ps^-1, H₂, CO, CH₄, N₂, and H₂O molecules were observed to pass, while, perhaps counter-intuitively, in the third case, with the highest imposed angular velocity of 360° ps^-1 only CH₄ and H₂ molecules were able to pass through the pores leading to the filtrate area.