Electric field direction-induced gas/water selectively entering nanochannel

Gas can spontaneously enter the hydrophobic nanochannel in the aqueous environment and is very difficult to be released from the nanochannel. Here, we report on a finding by the molecular dynamics simulations that the gas in the nanochannel can be released by tuning the direction of the external electric field. When the external electric field is perpendicular to the nanochannel wall, only gas molecules will enter the nanochannel as usual. When the external electric field is parallel to the nanochannel wall, the entered gas molecules will be replaced by water molecules and be released from the nanochannel. The selective entry of gas and water molecules into the nanochannel is the result of the distribution difference between water molecules inside and outside the nanochannel with the external electric field. This finding provides an important and novel mechanism for gas–water separation.