Metal–Organic-Framework-Derived CuO–ZnO@CN Hollow Nanoreactors: Precise Structural Control and Efficient Catalytic Performance

Hollow carbon–nitrogen nanoreactors constitute a class of porous materials that have widespread application owing to their large inner cavities, low densities, core–shell interfaces, and enrichment effects. Direct carbonization of precursors is the simplest and most economical method to prepare porous carbon–nitrogen materials; however, this method requires high temperatures, thus yielding nonoxide structures. In this study, CuO–ZnO@CN (CN: carbon–nitrogen layers) is prepared using the two-step heating of zeolitic imidazolium skeleton-8 (ZIF-8) coated with CuO–ZnO precursors. During carbonization, the ZIF-8 nanoparticles are converted into carbon–nitrogen layers at high temperatures. Next, a heating process based on the autocatalytic effect of Cu can be used to etch the hollow structure prepared by the carbon–nitrogen layers. The CuO–ZnO@CN hollow composites fabricated using this method exhibit excellent catalytic properties for the ethynylation of formaldehyde. The proposed strategy can be used to develop techniques for syntheses of readily reducible carbon oxide claddings and their composites.