@Article{icces.2023.09144,
AUTHOR = {JianHao Qian, HengAn Wu, FengChao Wang},
TITLE = {Gas	Transport	Through	Nanochannels:	Surface	Effect	and	Molecular	 Geometry	Effect},
JOURNAL = {The International Conference on Computational \& Experimental Engineering and Sciences},
VOLUME = {26},
YEAR = {2023},
NUMBER = {4},
PAGES = {1--2},
URL = {http://www.techscience.com/icces/v26n4/54070},
ISSN = {1933-2815},
ABSTRACT = {Gas	transport	through	nanochannels	is	ubiquitous	in	nature	and	also	plays	an	important	role	in	industry.
The	gas	flow	in	this	regime	can	be	described	by	the	Knudsen	theory,	which	assumes	that	molecules diffusely	
reflect	on	the	confining	walls [1].	However, with	the	emergence	of	low	dimensional	carbon-based materials	
such	as	graphene	and	carbon	nanotubes,	it	has	been	evidenced	that	this	assumption	might	not hold	for	some	
atomically	smooth	surfaces,	resulting	in	an	anomalous	enhancement	of	gas	flux [2]. Moreover,	in	Knudsen	
theory,	gas	molecules	are	usually	treated	as	mass	points	and	distinguished	solely	by	molecular	weight,	which	
cannot	 interpret recent	 experiments that	 gases	 with	 similar	 molecular	 weight	 exhibit	 a	 remarkable	
difference	in	 the	 flow	 rate [3].	In	 this	 talk,	 I	 will	 present	 our	 recent	 research	 progress	in	 this	 field.	We	
meticulously	investigated	the	gas	transport	through	nanochannels.	For	the	enhancement	of	gas	flux	through	
nanochannels with	 atomically	 smooth	 walls,	 we	 revealed	 the	 underlying	 mechanism	 as	 the surface	
morphological	effect	on	the	gas	collision	with	solid	walls [4].	Even	a	subtle	distinction	of	surface roughness	
results	 in	 specular	 scattering	 on	 graphene	 surfaces	 while	 diffuse	 scattering	 on	 molybdenum	 disulfide
surfaces. We	 found	 that the	curvature	effect	could	 reduce	 the	 surface	 roughness	 of	interaction	potential
surfaces,	 leading	 to	 an	 additional	 enhancement	 on	 the	 gas	 flow	 rate.	 We	 also ascertain	 the	 molecular	
geometry	effect	on	the	transport	of	various	gases	through	nanochannels [5].	Gas	molecules	with	a	complex	
geometry	are	more	likely	to experience	multiple	reflections	on	the	surface,	leading	to	the	diffuse	scattering	
and	 a	 reduced	 flux.	 During	 the	 collision,	 only	 the	 normal	 translational	 kinetic	 energy acts	 as	 a	 positive	
contribution	to	the	successful	reflection,	while	the	vibrational,	rotational	and	tangential	translational	kinetic	
energies	are	all	ineffective	in	this process.	The	ratio	of	this	ineffective	energy	to	the	initial	kinetic	energy	is	
suggested	as	the	criterion	whether	the	gas	can	disengage	from	the	wall	after	each	collision. These	insights	
are	expected	to deepen	the	understanding	of	gas	transport	in	nanochannels,	paving	a	promising	way	in	the	
gas permeation	 control. Our	 work	 also offers	 a	 new	 perspective	 to	 extend	 Knudsen	 theory	 for	 broader	
applications.	},
DOI = {10.32604/icces.2023.09144}
}