Enhancing CO₂ Reduction: Insights from In-Liquid Microwave Plasma Chemical Vapor Deposition

Fossil fuels have played a vital role in human progress; however, their combustion comes at a considerable environmental expense, releasing substantial CO2 emissions and contributing to global warming. Thus, there is an urgent need to replace fossil fuels with environmentally friendly, carbon-neutral alternatives. To address this challenge, the study employed a novel in-liquid microwave plasma chemical vapor deposition method to convert CO2 into valuable gases, such as CO, H2, CH4, and O2, and fuels, like methanol. The effect of the conductivity of the solution on CO2 conversion was studied using ultrapure water and aqueous KCl solution. It is observed that a higher CO2 conversion rate into CO and methanol was detected in the aqueous KCl solution than in ultrapure water. Also, the effect of different electrode shapes, like cylindrical and conical, with and without a tungsten substrate was studied. The maximum CO2 conversion rate of 22.4% to CO is achieved using a conical-shaped electrode and KCl solution. Higher CO2 conversion efficiency into methanol is found in the conical-shaped electrode than in the cylindrical-shaped electrode. The mechanism involving the reduction of CO2 into CO and CH3OH is also discussed.