Sonochemical CO2 Reduction to Acetamide and Liquid C2+ Oxygenates Using a Liquid Metal Gallium-Based Reductant

Carbon dioxide emission is a major cause of environmental concern, such as global warming and ocean acidification. Therefore, there is an ongoing search for feasible carbon dioxide reduction processes that utilize renewable energy to convert CO2 into a valuable product. Here, we report a versatile sonochemical process for the permanent removal and conversion of carbon dioxide into acetamide and liquid oxygenates using a Ga liquid metal-based reductant. Liquid metals are ideal for CO2 reduction due to their notable catalytic properties at low temperatures, nontoxicity, and relatively low cost. The process involves ultrasonication of water-suspended liquid Ga droplets, leading to the formation of GaOOH, which is further sonicated in the presence of an aqueous solution of NH4OH with a CO2 feed at a low temperature of 70 °C. Liquid C2 and C3 oxygenate products were formed including industry-relevant acetamide, ethanol, and acetone platform chemicals. In addition, solid-phase gallium nitride and oxynitride nanomaterials were formed, which could be utilized in various catalytic and electronic applications.