Construction of Hollow Ultrasmall Co 3 O 4 Nanoparticles Immobilized in BN for CO 2 Conversion.

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.