CuO Nanoparticles Supported on NiFe2O4 Nanorods as a Visible-Light Photocatalyst for the Click Reaction

Abstract Embedding different metal oxide nanoparticles on calcined metal-organic frameworks (MOFs) with bimetallic structures is a smart strategy for the architecture of heterogeneous nanostructures. Herein, the organization of CuO nanoparticles on NiFe2O4 nanorods, which themselves are calcined by MIL-88B(Fe2/Ni) as a bimetallic MOF, was utilized for the click reaction under visible-light irradiation (λ > 420 nm). In the first step, MIL-88B(Fe2/Ni) nanorods were prepared as a host bimetallic MOF by a solvothermal method. The NiFe2O4 nanorods were obtained via the calcination of MOFs. Then, CuO was organized on the NiFe2O4 nanorods to obtain a type of magnetic heterogeneous NiFe2O4@CuO photocatalyst with an S-scheme heterojunction system. Under visible-light irradiation, this heterogeneous nanostructure acts as a highly efficient photocatalyst for the formation of triazole rings via a click reaction, which can compete with the best reported photocatalyst systems. The obtained results showed that the presence of Ni and Fe metals in the presence of CuO nanoparticles can significantly enhance the separation of photo-generated electron-hole pairs and then enhance their photocatalytic performance. Consistent with the results of photoelectrochemical findings such as electron paramagnetic resonance, Mott-Schottky, and UV-visible diffuse-reflectance spectra spectrum, the appropriate band gap structures of this nanorod structure ensure the generation of electrons required for the reaction under visible-light irradiation. The present study can provide insights into the calcination of MOFs to create heterogeneous structures as well as develop S-scheme heterojunction materials for click reactions and other organic reactions under visible-light irradiation.