Construction of Hollow Ultrasmall Co₃O₄ Nanoparticles Immobilized in BN for CO₂ 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 Co₃O₄ nanoparticles (NPs) immobilized in boron nitride (denoted as Co₃O₄@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 Co₃O₄@BN not only possesses a hollow structure but also shows highly dispersed Co₃O₄ NPs and high loadings of up to 34.3 wt %. Owing to the ultrafine particle size and high dispersity, the optimized Co₃O₄@BN exhibits high catalytic activity for the cycloaddition of CO₂ to epoxides under mild conditions (i.e., 100 °C and CO₂ balloon), resulting in at least 4.5 times higher yields (99%) of styrene carbonate than that of Co₃O₄ synthesized by the pristine ZIF-67. This strategy sheds light on the rational design of hollow MO materials for various advanced applications.