Catalytic ultrasound-driven synthesis of syngas from CO2 saturated water

Conventional catalytic CO₂ reduction into value-added products often encounters challenges such as high energy barriers and complex operational setups. Here, we introduce a sonocatalysis approach to CO₂ reduction in water under ambient conditions. In an acoustic cavitation-induced high-energy local environment, the Cu nanoparticles incorporated on the ZnAl-layered double oxide create a favorable energy barrier for CO₂ reduction in water, a CO production rate of 23.8 μmol_CO g⁻¹ h⁻¹ with over 85% selectivity was achieved by ultrasonic irradiation of a CO₂-saturated aqueous solution at room temperature. Furthermore, more acoustic cavitation was produced with 5% CO₂ in argon dissolved in water, resulting in a higher CO productivity of 252.7 μmol_CO g⁻¹ h⁻¹, 11 times larger than pure CO₂. Hydrogen production also increased with acoustic cavitation, creating a syngas mixture with a CO to H₂ ratio of 1.2 to 2.2. This approach produces a high sonochemical efficiency of 211.1 μmol kJ⁻¹ g⁻¹ L⁻¹ for the ultrasound-driven fuel production from CO₂ and water. These results highlight the use of cavitation to provide an alternative approach to CO₂ conversion.