Preassembly Strategy to Single Cu-N3 Sites Inlaid Porous Hollow Carbonitride Spheres for Selective Oxidation of Benzene to Phenol.

Developing single-atom catalysts with porous micro-/nano-structures for high active-site accessibility is of great significance but still remains a challenge. Herein, we for the first time report a novel template-free preassembly strategy to fabricate the single Cu atoms mounted porous hollow graphitic carbonitride spheres via thermal polymerization of supramolecular preassemblies composed of melamine-Cu complex and cyanuric acid. Atomically dispersed Cu-N3 moieties were unambiguously confirmed by the spherical aberration correction electron microscopy and extended X-ray absorption fine structure spectroscopy. More importantly, it exhibits outstanding catalytic performance for selective oxidation of benzene to phenol at room temperature, especially shows extremely higher phenol selectivity (90.6 vs. 64.2%) and stability than the supported Cu nanoparticles, originating from the isolated unique Cu-N3 sites in the porous hollow structure. 86% of benzene conversion with 96.7% of unexpectedly high phenol selectivity at 60 o C for 12 h has been achieved, suggesting a great potential for practical application. This work paves a new way to fabricate variety of single-atom catalysts with diverse graphitic carbonitride architectures.