Calix[4]pyrrole Stabilized PdNPs as an Efficient Heterogeneous Catalyst for Enhanced Degradation of Water-Soluble Carcinogenic Azo Dyes

One-pot synthesis of palladium nanoparticles (PdNPs) has been achieved using calix[4]pyrrole hydrazide (MCPTH) as both reducing as well as capping agent. The synthetic procedure involves the use of environmentally benign water as solvent media. MCPTH-PdNPs have been characterized by using various analytical techniques. Transmission electron microscope analysis visualized the presence of well-dispersed and spherical Pd nanoparticles with an average dimension of 3–4 nm. Powder X-ray diffraction pattern portrayed the presence of face-centered cubic crystal structured PdNPs. A zeta potential value of − 26.2 mV suggests better stability of the nanoparticles. The heterogeneous catalytic activity of MCPTH-PdNPs was studied by probing the reduction of two carcinogenic azo dyes, namely, methylene blue and methyl orange in the presence of sodium borohydride. A remedial pathway for the process of dye degradation is proposed where the catalytic activity of Pd is faciled by the transfer of electrons from MCPTH to the metal centre. The mechanism for dye degradation is further substantiated by Density Functional Theory (DFT) calculations. The results of this work provide not only insight into fabrication of nanoparticles using calixarene platforms but also open new vistas to environmental remediation. Graphic Abstract: [Figure not available: see fulltext.]