Interface Controlled Electric Field Swing Adsorption.

Influencing the adsorptive processes of gases by external stimuli is an ongoing research task of academic and technological relevance. Technologically external stimuli like pressure, vacuum, temperature, magnetic field, or electrical phenomena are the most common ones with which adsorptive and desorptive processes can be influenced. In the case of pure electric field swing adsorption (EFSA) of solid/gas mixtures, however, experimental knowledge concerning carbon materials is lacking so far. A new approach to the electrical field effect on gas adsorption and desorption is presented. Ar, N₂ and CO₂ interact with an all-solid composite material composed of activated porous carbon and silica characterized by a high amount of charged interfaces under isothermal conditions and ambient temperature. The intimate contact of both components in the composite allows for the formation of multiple resistor-conductor interfaces enabling the reversible physisorption of these gases using electric fields in the lower V and mA range. The adsorptive/desorptive swing effect depends on the polarizabilities of the gases in particular their dipoles and to an even larger extent on the field induced quadrupole moments of the probe gases Ar, N₂ and CO₂.