Synergistic Effects of Carbon Dots and Palladium Nanoparticles Enhances the Sonocatalytic Performance for Rhodamine B Degradation in the Absence of Light

Carbon dot (CD) and palladium nanoparticles (Pd NPs) composites are semiconducting materials having tremendous applications in catalysis with suitable bandgap. However, their combination with suitable polymer matrix in sono-photo-catalysis has not been explored. Herein, we have synthesized and characterized a new nano-hybrid catalyst from polyamide cross-linked CD-polymer and subsequent deposition of Pd NPs. Sonocatalytic activity of 99% rhodamine B dye-degradation was achieved in mere 5 minutes (min) under dark. Model catalyst replacing CD with benzene and other control studies revealed that synergistic effects of CD and Pd NPs enhances the sonocatalytic activity of nano-hybrid catalyst. Interestingly, visible light did not influence the activity significantly. While mechanistic investigations suggest that generation of reactive oxygen species on the surface of CD-polymer initiated by ultrasound which further facilitated by Pd NPs is the key for remarkable catalytic activity (rate constant 0.99 min^-1). Recyclable heterogeneous catalyst under ambient conditions are promising for the utility of exploring sono-assisted dark-catalysis for several avenues.