A cylindrical dielectric barrier discharge (DBD) reactor has been developed for the conversion of undiluted CO2 into CO and O2 at atmospheric pressure and low temperatures. Both the physical and chemical effects on reaction performance have been investigated for the addition of BaTiO3 and glass beads into the discharge gap. The presence of these packing materials in the DBD reactor changes the physical characteristics of the discharge and leads to a shift of the discharge mode from a typical filamentary discharge with no packing to a combination of filamentary discharge and surface discharge with packing. Highest CO2 conversion and energy efficiency are achieved when the BaTiO3 beads are fully packed into the discharge gap. It is found that adding the BaTiO3 beads into the plasma system enhances the average electric field and mean electron energy of the CO2 discharge by a factor of 2, which significantly contributes to the enhancement of CO2 conversion, CO yield and energy efficiency of the plasma process. In addition, highly energetic electrons (> 3.0 eV) generated by the discharge could activate BaTiO3 photocatalyst to form electron-hole pairs on its surface, which contributes to the enhanced conversion of CO2.

A coaxial dielectric barrier discharge (DBD) reactor has been developed for plasma-catalytic conversion of CO2 into value-added chemicals at low temperatures (<150 o C) and atmospheric pressure. The effect of specific energy density (SED) on the performance of the plasma process has been investigated. In the absence of a catalyst in the plasma, the maximum conversion of CO2 reaches 21.7 %. The synergistic effect from the combination of plasma with photocatalysts (BaTiO3 and TiO2) at low temperatures contributes to a significant enhancement of both CO2 conversion and energy efficiency by up to 250%. The synergy of plasma-catalysis for CO2 conversion can be attributed to both the physical effect induced by the presence of catalyst pellets in the discharge and the photocatalytic surface reaction driven by the plasma.

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