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

[Image: see text] Carbon dot (CD) and palladium nanoparticle (Pd NP) composites are semiconducting materials having tremendous applications in catalysis with suitable band gaps. However, their combination with a suitable polymer matrix in sonophotocatalysis has not been explored. Herein, we have synthesized and characterized a new nanohybrid catalyst from a polyamide cross-linked CD-polymer and subsequent deposition of Pd NPs. A sonocatalytic activity of 99% rhodamine B dye degradation was achieved in mere 5 min in the dark. A model catalyst replacing CDs with benzene and other control studies revealed that the synergistic effects of CDs and Pd NPs enhance the sonocatalytic activity of the nanohybrid catalyst. Interestingly, visible light did not influence the activity significantly. Mechanistic investigations suggest that generation of reactive oxygen species on the surface of the CD–polymer initiated by ultrasound, which is further facilitated by Pd NPs, is the key for remarkable catalytic activity (a rate constant of 0.99 min(–1)). Recyclable heterogeneous catalysts under ambient conditions are promising for exploring sono-assisted dark catalysis for several avenues.