Humidity-assisted selective reactivity between NO2 and SO2 gas on carbon nanotubes

SWCNT-aminopolymer composites on mesoporous alumina for fast, room-temperature detection of ultra-low concentrations of NO2 by mediation of water vapour

“…Yao et al carried out response and recovery studies for NO 2 and SO 2 on SWCNT for humidity up to 92% [30]. Unlike in our case, where humid air is used only in the first stage of recovery, the Yao et al carried out the entire measurement under the same humid condition.…”

“…In these instances, a predicted reaction pathway is NO 2 + H 2 O ad → HONO + HNO 3 ad Since some H 2 O molecules remain adsorbed on the SWCNTpolymer surface at the W-M baseline, this additional mechanism could be present in the H 2 O-enriched SWCNT-polymer composites. The presence of HNO 3 leads to generation of C O bonds which then facilitates the production of adsorbed NO 3 [30,35]. Similarly, HONO dissociates quickly in faint visible light to form NO that can facilitate another pathway (by reacting with NO 2 ) to produce NO 3 as shown above.…”

“…This shift essentially changes the binding and charge transfer characteristics for gas molecules. For example, Yao et al showed that for intrinsic CNT, charge transfer occurs from CNT to water molecules and for p-doped CNT it changes direction and charge transfer occurs from H 2 O molecules to CNT [30].…”

“…The models which calculate gas adsorption energy on CNT, often assume pristine state. However, the presence of p-doping can substantially change the electrical response to adsorbed molecules [30]. The presence of aminopolymer on the surface further complicates the situation.…”

Investigation of interaction hydrogen sulfide with (5,0) and (5,5) single-wall carbon nanotubes by density functional theory method

“…The N doping decreases the hydrogen atomic adsorption energies. Humidity-assisted desorption of SO 2 and NO 2 has been experimentally investigated on carbon nanotubes [22]. The results showed that the resisted desorption of SO 2 on carbon nanotubes in dichloroethane solution increases at high humidity level (92%) and no change was observed in low humidity level, while there was also no change in desorption of NO 2 in the different levels of humidity.…”