Effect of Electric Fields on the Radiation-Induced Reaction between Carbon Dioxide and Graphite

The effect of an electric field on the γ‐ray‐induced reaction of CO formation from CO₂ and graphite was investigated. The experiment was carried out at room temperature under an exposure dose rate of 1.5×10⁵ R/h using diodelike tubes with graphite and metal (tungsten or molybdenum) electrodes filled with CO₂ gas at 300 mm Hg. When a negative voltage was applied to the graphite to obtain a saturation current, the yield of CO was about 2.5 times as much as that in the absence of any field. However, on application of a positive field, the yield was not significantly different than the zero field case. The G value for CO formation was found to be 0.62∼1.01 in the absence of the field. The ionic reaction mechanisms $${\mathrm{CO}}_2^{+}+{\mathrm{C}}^{-}(\mathrm{graphite\; electrode}\text{)→2}\mathrm{CO}$$ and/or $${\mathrm{CO}}_2^{+}+{\mathrm{C}}^{-}(\mathrm{graphite\; electrode}\mathrm{)\to }\mathrm{C}(\mathrm{graphite})\mathrm{O}+\mathrm{CO}$$ are proposed for the increased yield of CO in the case of negative voltage application to the graphite.