Confined pyrolysis transformation of ZIF-8 to hierarchically ordered porous Zn-N-C nanoreactor for efficient CO2 photoconversion under mild conditions

Rational design and fabrication of metal–organic framework (MOF)-derived ordered hierarchical macro-/meso-/microporous N-doped carbon materials featured with the atomically dispersed metal atoms can effectively enhance their catalytic performance. Herein we develop a template-assisted strategy, namely the confined growth and pyrolysis of single-crystalline zeolite imidazolate framework-8 (ZIF-8) in three-dimensional ordered template voids, to create hierarchical porosity in MOFs-derived N-doped carbon materials. The as-synthesized single-atom Zn on N-doped hierarchically ordered porous carbon polyhedrons (Zn-N-HOPCPs) show integrated Lewis acid (single-atom Zn) and base sites (pyridinic N), high surface area (1128 m2·g−1), large pore volume (0.90 cm3·g−1), periodically interconnected open windows (~55 nm), highly accessible micro/mesopore channels (0.55, 0.8, 1.2, and 4 nm), and abundant Zn content (5.8 wt%). The hierarchical nanoarchitecture (macro-/meso-/micropores) significantly facilitates mass transfer for bulky-molecule-involved reactions and exposes inside active sites, resulting in satisfactory CO2 photoconversion under mild conditions. The strategy presented here sheds light on the design and fabrication of various hierarchically ordered porous carbon decorated with atomically dispersed metal atoms for other important applications.