N-rich MOFs Derived N-doped Carbon Nanotubes Encapsulating Cobalt Nanoparticles as Efficient and Magnetic Recoverable Catalysts for Nitro Aromatics Reduction

Abstract A rational and convenient strategy was designed to synthesize high level N-doped Co@NCNTs composites derived from adenine-based AD-MOF-1 and Bio-MOF-11 via one-step pyrolysis method. Adenine can be used as an endogenous nitrogen source to apparently increase the N content of the materials. N-rich CNTs form a protecting layer for Co nanoparticles to avoid the aggregation of metal nanoparticles. The abundant nitrogen content can enhance electronic conductivity and bring additional active sites. The prepared Co@NCNTs display high catalytic efficiency for various nitro aromatics reduction in aqueous solution. The Co@NCNT-1-800 implies outstanding catalytic efficiency of 96% for the reduction of 4-NP. A mechanistic analysis revealed the abundant Co catalytic sites on the surface of catalysts to promote electron transfer efficiency and improve catalytic performance significantly. Moreover, the magnetic Co-based catalysts remained excellent catalytic activity and reusability even after five cycles.