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Abstract This paper develops a simple and green process of synthesizing palladium nanoclusters (PdNCs) capped on the hybrid nanocomposite based on biodegradable polysaccharides, 2-hydroxypropyl-β-cyclodextrin (HPCD) and alginate (Alg) through an ionotropic gelation mechanism. PdNCs were biosynthesized from aqueous extract of Burdock root (BR), Arctium lappa. The nanocomposite PdNCs/HPCD/Alg was characterized by techniques like UV–Vis, FTIR, EDX, FESEM, TEM, HR-TEM and TG-DTA. The crystal palladium nanoparticles were found to distribute in cluster shape with a size of 4–10 nm. EDX data showed that average amount of palladium capped on the hybrid nanocomposite was approx. 4.7% (w/w). PdNCs/HPCD/Alg exhibited highly catalytic activity for degradation of pollutants including 4-nitrophenol, methyl orange and rhodamine B in wastewater and leaching mechanism of the nanocatalyst was showed. In particular, the nanocomposite showed excellent aqueous-phase catalytic performance for free-triphenylphosphine Sonogashira cross-coupling reaction. The nanocatalyst could be efficiently reused without much compromising with its activity. Graphical abstract Unlabelled Image Highlights • Biogenic PdNCs/HPCD/Alg first synthesized by aqueous extract of Arctium lappa • Characterization of the nanocomposite determined by modern analytic technology • Recyclable catalytic activity of PdNCs performed for degradation of pollutants • Recyclable catalytic activity of PdNCs performed for Sonogashira reaction in water [ABSTRACT FROM AUTHOR]

[Display omitted] • Small size Pd nanocluters (2–5 nm) can accelerate the reaction kinetics and have superior catalytic effect. • The Pd nanoclusters and the sulfur vacancy on the substrate have synergistic effect to enhance the catalytic ability for HER. • The catalyst in the form of metal-supported achieves low overpotential (25 mV vs. RHE) at 10 mA cm−2 and high stability. Hydrogen energy is regarded as the clean energy alternative for fossil energy. Hydrogen evolution reaction (HER) is a sustainable way for the production of hydrogen energy. However, commercial platinum (Pt) catalysts for HER are expensive and scarce, which will not fully meet the demand of the future market. Therefore, scientists have been actively exploring alternatives to Pt-based catalysts. Studies have shown that palladium (Pd) and Pt have similar catalytic activity in HER. Small molecular Pd nanoclusters can be used as a perfect HER activity center. Herein, anchoring of Pd nanoclusters (Pd NCs) on sulfur-vacancy-enriched ZnIn 2 S 4 nanosheets (Pd/ZIS-T) has been successfully achieved. The zeta potential value for ZnIn 2 S 4 is −59.9 mV, indicating that the surface of ZnIn 2 S 4 is abundant negatively charged in deionized water, thus providing plentiful anchoring sites to absorb Pd2+. The results show that the synergistic effect of Pd NCs and sulfur vacancies will endow the obtained catalyst with excellent electrocatalytic activity and stability. It also managed to reducing costs by reducing noble metal content. In particular, the Pd/ZIS-T electrocatalyst with excellent performance delivered low overpotential of 25 mV at 10 mA cm−2 and small Tafel slope of 33 mV dec-1 in acidic electrolyte. [ABSTRACT FROM AUTHOR]

Hydroxy-CNT were modified with optically active α-amino acids. The resulting chiral derivatives were directly palladated with Pddba and used to catalyze the hydrogenation of α-acetamidostyrene and α-phenylcinnamic acid as well as the hydroarylation of norbornene with iodoarenes. All the catalytic reactions afforded products containing a new chiral carbon center in high yields, though as racemates. Apparently, asymmetric induction is precluded because the palladium sites on the CNT surface are spatially apart from the chiral carbon centers in amino acid groups. [ABSTRACT FROM AUTHOR]