Boosting Fenton-like Catalysis via Electron Tunneling-Based C-Co Charge-Transfer Bridge in Nitrogen-Doped Cobalt@Carbon Nanotube-Grafted Carbon Polyhedron

Transition metal@carbon heterostructures are an emerging material paradigm for enhancing Fenton-like catalysis, and the synthesis of this heterostructure with designed functionality derived from metal-organic frameworks (MOFs) is interesting and challenging. Herein, we developed MOF-on-MOF nanoarchitectures to construct a selectively functionalized nitrogen-doped cobalt@ carbon nanotube-grafted carbon (Co@NCNT/NC) polyhedron via the thermal treatment of elaborately designed ZIF-8@ZIF-67 core- shell precursors for water decontamination. Strikingly, the Co@ NCNT/NC heterojunction is more conducive to transporting electrons to adjacent Co atoms than Co@NC, because of its high d-band center, strong conductivity, and the formation of multiple C-Co bonds for electron tunneling. Deliberate material design and theoretical simulations unveil that the dual reaction centers in C-Co bonds significantly alter the electronic structure of Co atoms, which creates the electron-rich Co centers further enhancing the specific adsorption/activation of H2O2. Simultaneously, the loss of electrons in Co species reduces the surrounding energy levels, resulting in the electrons of pollutants adsorbed on the surface of Co@NCNT/NC entering Co species through C-Co charge -transfer bridges, thus maintaining the redox cycle of Co2+-* Co3+-* Co2+, and realizing the efficient and stable removal of pollutants. This work highlights the importance of the transition metal@carbon heterostructures to advanced catalytic oxidation and the MOF-on-MOF nanoarchitectures on nanomaterials synthetic chemistry.