Facile synthesis of spherical porphyrin polymer-supported cobalt nanoparticles for the efficient catalytic hydrogenation of 4-NP†

Abstract

A spherical porphyrin polymer-supported cobalt nano-catalyst P-TPP-Co(II) was synthesized using a simple method that does not require additional reduction or pyrolysis steps, where P-TPP is tetraphenyl porphyrin polymer. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses demonstrated that Co ions were reduced in situ on the surface of the porphyrin polymer microspheres during the reduction experiment, and nanoflower structures were grown. The catalyst exhibited high catalytic activity for the hydrogenation of 4-nitrophenol under mild conditions, with a first-order reaction rate constant of 0.274 min⁻¹. Experimental results confirmed that Co played a crucial role in the catalytic reaction. The high performance observed can be attributed to the unique properties of the Co nanoflower catalyst structure and the synergistic effects between Co elements and porphyrin polymers. This includes the strong adsorption capability of the spherical porphyrin polymer carrier for organic molecules and the excellent electrical conductivity of the porphyrin molecules to the Co nanoflower. Furthermore, the cobalt-based catalyst is relatively inexpensive and can be recycled up to six times, facilitating low-cost hydrogenation of 4-nitrophenol to 4-aminophenol. Additionally, in the catalytic degradation of Rhodamine B, the catalyst demonstrated good catalytic performance.