Piezoelectric catalysis for efficient reduction of CO₂ using lead-free ferroelectric particulates

The increase in global energy demand, together with a rise in carbon dioxide (CO₂) levels have encouraged research into the reduction of CO₂ into useful chemicals and fuels. In this paper, we demonstrate the piezo-catalytic reduction of CO₂ using lead-free lithium-doped potassium sodium niobate (KNN) ferroelectric ceramic particulates. The application of acoustic waves generated by ultrasound to a suspension of the ceramics particles creates pressure waves result in a large change in the spontaneous polarisation of the KNN particles via the piezoelectric effect, which in turn creates surfaces charges for CO₂ reduction. The effect of CO₂ gas concentration, the presence of dissolved species, and catalyst loading on piezo-catalytic performance are explored. By optimization of the piezo-catalytic effect, a promising piezo-catalytic CO₂ reduction rate of 438 μmol g⁻¹ h⁻¹ is achieved, which is much larger than the those obtained from pyro-catalytic effects. This efficient and polarisation tuneable piezo-catalytic route has potential to promote the development of CO₂ reduction via the utilisation of vibrational energy for environmental benefit.