Co-Zn bimetallic oxide & hydroxyfluoride nanowires: highly active catalyst for catalytic transfer hydrogenation of furfural

Abstract

Co-Zn bimetallic hydroxyfluoride nanorods (CoZnF) were synthesized at room temperature in an aqueous solution. After calcination at 330 °C in air, CoZnF was partially decomposed to form CoZn bimetallic oxide & hydroxyfluoride (CoZnO&CoZnF) nanowires. The higher electronegativity of fluorine compared to oxygen reduces the valence electron density of oxygen in CoZnF, thereby weakening the metal‑oxygen bonds, and generating abundant oxygen vacancy sites in CoZnO&CoZnF. Electron transfer between cobalt and zinc maintains cobalt in the Co(II) oxidation state. Catalytic results demonstrate the potential of CoZnO&CoZnF for selective hydrogenation of furfural to furfuryl alcohol (FA). Lewis acid-base pairs (Co²⁺/Zn²⁺-O²⁻) and oxygen vacancy sites act as active sites for catalytic transfer hydrogenation (CTH). The nanowire structure and highly accessible active sites enhance catalytic activity. CoZnO&CoZnF exhibits an excellent catalytic activity, achieving 98.1 % yield of furfuryl alcohol (FA) with a selectivity of 99.2 %. Mechanistic insights from ¹HNMR analysis and kinetic studies elucidate the reaction pathway, including activation energy determination.