Metal–Organic-Framework-Derived\nCuO–ZnO@CN\nHollow Nanoreactors: Precise Structural Control and Efficient Catalytic\nPerformance

Hollow carbon–nitrogen nanoreactors\nconstitute\na class of\nporous materials that have widespread application owing to their large\ninner cavities, low densities, core–shell interfaces, and enrichment\neffects. Direct carbonization of precursors is the simplest and most\neconomical method to prepare porous carbon–nitrogen materials;\nhowever, this method requires high temperatures, thus yielding nonoxide\nstructures. In this study, CuO–ZnO@CN (CN: carbon–nitrogen\nlayers) is prepared using the two-step heating of zeolitic imidazolium\nskeleton-8 (ZIF-8) coated with CuO–ZnO precursors. During carbonization,\nthe ZIF-8 nanoparticles are converted into carbon–nitrogen\nlayers at high temperatures. Next, a heating process based on the\nautocatalytic effect of Cu can be used to etch the hollow structure\nprepared by the carbon–nitrogen layers. The CuO–ZnO@CN\nhollow composites fabricated using this method exhibit excellent catalytic\nproperties for the ethynylation of formaldehyde. The proposed strategy\ncan be used to develop techniques for syntheses of readily reducible\ncarbon oxide claddings and their composites.