Biocompatible starch-halloysite hybrid: An efficient support for immobilizing Pd species and developing a heterogeneous catalyst for ligand and copper free coupling reactions

Abstract

Combining the exceptional features of halloysite and starch, a unique hybrid was synthesized based on conjugation of amine-functionalized starch with Cl-halloysite nanoclay followed by coordination of Pd (II) acetate. The resultant hybrid catalyst, Pd@Hal-SA, was used as a heterogeneous catalyst for promoting copper and ligand-free coupling reactions under mild reaction condition. The catalyst exhibited high catalytic activity and recyclability (up to 10 reaction runs) with slight loss of the catalytic activity that stemmed from slight Pd leaching. The comparison of the catalytic activity of Pd-Hal, Pd-SA and Pd@Hal-SA confirmed the superior performance of the latter, indicating the contribution of two components, SA and Hal to the catalysis. Moreover, the catalytic activity of Pd@Hal-SA was higher than that of Pd@Hal + SA, implying that the use of hybrid system was more efficient that use of individual components in a separated form, due to the synergism between SA and Hal.

Halloysite nanotubes filled with salicylic acid and sodium diclofenac: effects of vacuum pumping on loading and release properties

“…Consequently, this unique property can be exploited for the surface modification with organic molecules (e.g., polymers, biopolymers or surfactants), through both electrostatic and van der Waals interactions, thus leading to the design of hybrid and bio-hybrid systems that find applications in a broad range of applications [25][26][27][28][29][30][31][32][33][34]. In general, electrostatic interactions are convenient to target the interaction/adsorption site for halloysite nanotubes [35][36][37][38]. Most interestingly, halloysite nanotubes can be loaded with negatively charged active species, such as biological molecules, anti-corrosion compounds and antioxidants that can be protected inside the inner lumen of the nanotubes [39][40][41].…”

Study of the effect of the ligand structure on the catalytic activity of Pd@ ligand decorated halloysite: Combination of experimental and computational studies

“…In continuation of our research on the development of environmentally‐benign catalytic protocols for chemical transformations, including hydrogenation reaction, recently we have disclosed the outstanding performance of Hal as a catalyst support in its functionalized or hybrid forms . To shed light to the chemistry of Hal, we exploited both experimental and computational chemistry and attempted to find the relationship between the structural features and catalytic activities of Hal‐based catalysts .…”

Amperometric Oxygen Sensor Based on Bimetallic Pd-Cu/C Electrocatalysts

“…This is owing to the high activation energy of the Oads,Cu, further reducing the oxygen atoms. The adsorbed oxygen atom in Equation ( 4) had to migrate to the Pd sites, Oads,Pd, searching for low activation energy in Equation (5). The doped Cu atoms, besides breaking the O-O bond, could also weaken the Oads-Pd binding in terms of the electronic interaction in which the surface Cu lowered the d-band center of the Pd surface and decreased the interaction with the oxygen adsorbate [18].…”

“…However, the high cost of Pt metal and its CO poisoning compel researchers to pay attention to substituting Pt-based cathodes [2][3][4]. Pd is a potential alternative to replace the Pt electrode because of its inexpensive nature and high biocompatible activity [5]. To further reduce the costs of the electrode, researchers alloyed Pd matrix with transition metal in a Pd matrix, for example, Co, Ni, and Cu.…”