Microwaves (MW) and radio frequency (RF) dielectric heating were used to facilitate the regeneration of CO 2rich amine solutions, and the mechanism of the rate enhancement by dielectric heating was discussed. Dielectric measurements of aqueous solutions of monoethanolamine (primary amine), 2-(ethylamino)ethanol (secondary amine), and N-methyl diethanolamine (tertiary amine) revealed that the formation of carbamate and bicarbonate ions by CO 2 absorption improves the dielectric loss tangent. Dielectric heating by MWs (2.45 GHz, 915 MHz) and RF (200 MHz) was compared to facilitate regeneration of the CO 2 -rich amine solution at a constant power of 40 W. The CO 2 release rate was the highest at 2.45 GHz in all aqueous amine solutions, which was 1.47 to 1.74 times that of conventional heating by an oil bath operated at 120 °C. However, the CO 2 release rate decreased as the frequency decreased to 915 and 200 MHz. Electromagnetic field simulation suggested that CO 2 release was enhanced owing to the generation of a more intense electric field at 2.45 GHz than at lower frequencies.

Microwaves (MWs) with a frequency of sub–gigahertz or multi–gigahertz can promote a rotation of polar molecules and a vibration of electric charges through an interaction with the alternating electric fields which comprise the MWs. The MWs can also promote the rotation of dipoles formed at the interface of Schottky junctions and semiconductor heterojunctions (e.g. p–n junction), leading us to expect that photoinduced electron transfer reaction at the interface can be perturbed by the dipole rotation induced by MWs. In this paper, we successfully demonstrated that 2.45 GHz MWs can boost the photocurrents of FTO/TiO2 and FTO/TiO2/CdS electrodes, which are typically used electrode structures in quantum dot- or dye-sensitized solar cells. From photoelectrochemical analysis using precisely controlled MW power and illuminant wavelength, a model is proposed in which the tunneling electron transfer reactions occurring in photoelectrodes are accelerated by MW-induced perturbations of the interfacial dipoles at the tunneling interfaces. The model proposed here would open the way for novel applications of MWs in the fields of photo-, electro-, and photoelectrocatalysis with the aim of solar energy conversion.