Study On The Gas Storage Performance Of MoS₂ Nanotubes

Over the past century,non-renewable fossil fuels(such as oil and coal)have been rapidly consumed due to the population explosion,and the natural environment pollution has become increasingly serious.Therefore,the utilization of clean energy has attracted the attention and discussion of researchers.Hydrogen and methane are two typical clean energy sources,which have been widely studied due to their low cost and no pollution.However,the transportation cost of methane and hydrogen is relatively high.Many existing storage and transportation methods are not convenient and fast.Therefore,improving clean energy efficiency put high on the research agenda.With the development of nanotechnology,more and more nanomaterials have been widely studied.Many nanomaterials can be made into hollow nanotubes due to their unique physical properties,such as carbon nanotubes,boron nitride nanotubes,molybdenum disulfide nanotubes,etc.Nanotubes have a large specific surface area and can store not only low-density hydrogen(which is denser than both liquid and solid),but also relatively dense gases,such as nitrogen,nitrogen dioxide and sulfur dioxide.Gases stored can be quickly released by proper heating.Therefore,as a container for gas storage,nanotubes have broad application prospects.It is reasonable and indispensable to explore the gas storage performance of nanotubesIn the present study,we investigate the performance of molybdenum disulfide nanotubes(MoS2 NTs)as a medium for energy gas storage(hydrogen and methane)by using molecular dynamics simulations.Two representative armchair MoS2 NTs,(12,12)and(6,6),are considered in our study.The MoS2 NTs are found to effectively attract hydrogen and methane molecules through their surface and internal surface Under storage conditions(175 K and 10 MPa),the storage capacity of methane in MoS2 NTs can reach 7-8 wt%,depending on the diameter of MoS2 NTs.For hydrogen,the storage capacity is around 0.7-0.9 wt%.The gas weight percentage is linearly dependent on the environmental pressure from 10 MPa to 1 MPa at constant temperature.Meanwhile,the adsorption demonstrates an exponential relationship with the system temperature from 175 K to 425 K when pressure is maintained constant.Dynamic pressure simulations reveal that up to 80-90%of the stored gases can be spontaneously released as the pressure decreases from 10 MPa to 1 MPa(methane slightly more efficient than hydrogen),indicating high cyclic storage performance of the nanotubes.Our present theoretical findings shed new light on the utilization of MoS2 nanomaterials as a novel gas storage platform and we hope our results will promote future experimental efforts.