Surface and spatial engineering of ZnAl hollow multi-shelled structures for photothermal synergistic catalysis of glycerol carbonate synthesis

The synthesis of glycerol carbonate (GC) under mild conditions, a process constrained by thermodynamics, requires the simultaneous and efficient activation of both urea and glycerol. In this study, we developed a hydroxyl-rich Zn-Al-based hollow multi-shelled structure (ZnAl HoMS) catalyst that significantly enhances the urea alcoholysis reaction. Through optimization of its surface properties and spatial structure, this catalyst achieved a remarkable GC yield of 94.4 % under photo-thermal synergistic catalysis. Notably, even at a lowered temperature of 130 °C, it maintained excellent photo-thermal performance, delivering a GC yield of 78.2 % (selectivity>98 %), significantly higher than the 37.3 % yield obtained by pure thermal catalysis, representing a substantial increase of 40.9 %. Combined characterization and theoretical simulations revealed that the exceptional catalytic activity originates from the synergistic effect between its surface chemical properties and unique HoMS architecture. The surface Lewis acid-base sites effectively activate the carbonyl group of urea and the hydroxyl groups of glycerol, while the surface hydroxyl groups drastically reduce the energy barrier for the intramolecular cyclization step from 0.62 eV to 0.1 eV. Furthermore, the HoMS structure enhances light harvesting and promotes charge separation efficiency, facilitating the generation of photo-induced active species. These species work in concert with the acid-base sites to promote C-N bond cleavage and O-H bond dissociation. The rational design of surface properties and spatial structure of the catalyst in this work enables effective coupling of thermal and photocatalytic pathways, leading to a dramatic enhancement in reaction efficiency. This study provides new insights into the design of multifunctional catalysts and opens novel avenues for developing sustainable organic synthesis routes.