Ultrathin Zn-Gallate Catalyst: A Remarkable Performer in CO₂ and Propylene Oxide Polymerization

Abstract

Zn-gallate, an innovative catalyst synthesized using cost-effective zinc salts and gallic acid without complicated synthetic procedures, has been successfully applied in the copolymerization of CO 2 and propylene oxide. Zn-gallate displays exceptionally thin sheets with a thickness of 1−2 nm, leading to remarkable catalytic activity, high carbonate linkage proportion, and minimal monomer formation (3.01 kg/g-cat, f COd 2 = 0.97, and selectivity 91%). Zn-gallate outperforms other heterogeneous catalysts for the polymerization of CO 2 and propylene oxide. Furthermore, the polycarbonates synthesized using Zn-gallate exhibit substantially high molecular weights. A comprehensive characterization of Zn-gallate has been undertaken, employing SEM, TEM, BET, AFM, PXRD, IR, CP-TOSS 13 C NMR, XPS, TGA, and ICP analyses, which provided valuable insights into the exceptional catalytic properties of this novel catalyst.

Zinc Gallate Nanoplates on Microporous Organic Hollow Nanoplatforms for Enhanced Reductive CO2 Fixation to Formamides

“…Powder XRD studies revealed that the ZnG is a crystalline material with main diffraction peaks at 2θ values of 9.8°, 20.0°, 27.6°, 32.7°, 34.7°, and 40.2°, corresponding to (100), (102/200), (221/130/212), (232/230), (004/302), and (330/204/400) crystalline planes of the ZnG reported in the literature (Figure f) . In comparison, H-MOP was amorphous, matching with conventional features of MOPs reported in the literature .…”

“…The solid-state 13 C NMR spectrum of H-MOP showed aromatic carbon peaks at 146.8, 137.6, 131.3, and 122.7 ppm, in addition to alkyne peaks at 87–95 ppm and a sp 3 carbon peak at 64.7 ppm (Figure c) . In comparison, the solid-state 13 C NMR spectrum of ZnG showed a carbonyl carbon peak of carboxylate groups at 174.9 ppm and aromatic carbon peaks at 147.3 (aromatic carbons adjacent to oxygens), 123.5, and 119.2 ppm . As the amounts of ZnG in H-MOP@ZnGs increased, intensities of the corresponding 13 C peaks of ZnG gradually increased.…”

“…In comparison, the IR spectra of H-MOP@ZnGs showed main peaks at 1540, 1403, and 1026 cm –1 , corresponding to the CO vibration of carboxylate groups and aromatic CC and C–O vibrations of gallates, respectively, matching well with those of ZnG (Figure a). In the XPS spectra of H-MOP@ZnGs and ZnG, Zn 2p 1/2 and 2p 3/2 orbital peaks were clearly observed at 1045.7 and 1022.4 eV, respectively, indicating that the Zn species in the materials have an oxidation state of +2 (Figure b) . The solid-state 13 C NMR spectrum of H-MOP showed aromatic carbon peaks at 146.8, 137.6, 131.3, and 122.7 ppm, in addition to alkyne peaks at 87–95 ppm and a sp 3 carbon peak at 64.7 ppm (Figure c) .…”

“…However, resultant Zn-based materials could not surpass the catalytic activity of ZnGA. Recently, our research group has discovered that zinc gallate (ZnG) having a thin morphology surpasses the catalytic activity of ZnGA, while maintaining the selectivity in the insertion of carbon dioxide . However, ZnG has two important drawbacks.…”