Construction of Hollow Ultrasmall Co₃O₄ Nanoparticles Immobilized in BN for CO₂ Conversion

Abstract

Rational design and fabrication of metal−organic framework-derived metal oxide (MO) materials featuring a hollow structure and active support can significantly enhance their catalytic activity for specific reactions. Herein, a series of Co 3 O 4 nanoparticles (NPs) immobilized in boron nitride (denoted as Co 3 O 4 @BN) with highly open and precisely controllable structures were constructed by an in situ self-assembly method combined with a controlled annealing process. The obtained Co 3 O 4 @BN not only possesses a hollow structure but also shows highly dispersed Co 3 O 4 NPs and high loadings of up to 34.3 wt %. Owing to the ultrafine particle size and high dispersity, the optimized Co 3 O 4 @BN exhibits high catalytic activity for the cycloaddition of CO 2 to epoxides under mild conditions (i.e., 100 °C and CO 2 balloon), resulting in at least 4.5 times higher yields (99%) of styrene carbonate than that of Co 3 O 4 synthesized by the pristine ZIF-67. This strategy sheds light on the rational design of hollow MO materials for various advanced applications.

In Situ Pyrolysis of ZIF-67 to Construct Co2N0.67@ZIF-67 for Photocatalytic CO2 Cycloaddition Reaction

“…Increasing the catalyst dosage to 10 mg improved the yield to 95% (Figure b). However, when the dosage of Co 2 N 0.67 @ZIF-67­(450,2) is further increased to 15 mg, the yield of the target product drops to 85%, which can be attributed to the limiting mass transfer (Figure b). − Therefore, the optimal cycloaddition reaction of CO 2 and epichlorohydrin is conducted with 10 mg of Co 2 N 0.67 @ZIF-67­(450,2) at 1 bar of CO 2 pressure under visible light irradiation for 3 h.…”