Radiolytic approach for efficient, selective and catalyst‐free CO2 conversion at room temperature

Abstract : The present study proposes a new approach for direct CO$_2$ conversion using primary radicals from water irradiation. In order to ensure reduction of CO$_2$ into CO$_2^{-•}$ by all the hydrated electrons, we use formate ions to scavenge simultaneously the parent oxidizing radicals H$^•$ and OH$^•$ producing the same transient CO$_2^{-•}$ radicals. Conditions are optimized to obtain the highest conversion yield of CO$_2$. The goal is achieved under mild conditions of room temperature, neutral pH and 1 atm of CO$_2$ pressure. All the available radicals are exploited for selectively converting CO$_2$ into oxalate that is accompanied by H$_2$ evolution. The mechanism presented accounts for the results and also sheds light on the data in the literature. The radiolytic approach is a mild and scalable route of direct CO$_2$ capture at the source in industry and the products, oxalate salt and H$_2$, can be easily separated.