Nanoparticle Enhancement of Plasma-driven CO₂ reduction to Higher-order Hydrocarbons

By discharging ns high voltage pulses across an insulating substrate containing metal nanoparticles, we observe a significant enhancement in the generation of plasma through local field enhancement on the surface of the nanoparticles. Electromagnetic simulation shows local field enhancement on the order of 10X. Since the plasma is initiated by field emission of electrons, which depends exponentially on the electric field, we believe that this 10-fold increase can result in several orders of magnitude increases in the generation of plasma. By discharging ns high voltage pulses in CO₂-saturated water, we observe CO₂ reduction to higher-order hydrocarbons. Here, the plasma emission spectra exhibit Swan bands, which correspond to C₂ species, indicating that, in addition to reducing CO₂, C₂-species are formed, presenting the exciting possibility of converting a notorious greenhouse gas into an energy dense hydrocarbon fuel. We have also performed cryogenic NMR spectroscopy of various products in water and liquid ion chromatography(IC) ex-situ. Here, we observe clear peaks corresponding to formic acid, and acetic acid, which corresponds to a C₂-hydrocarbon species. We have also observed the presence of oxalates (i.e., C₂O₄²⁻), which is C₂ species, at approximately 150g/L using IC.