A family of two-dimensional salen-type lanthanide complexes was synthesized through a facile solution diffusion method. The two-dimensional lanthanide complexes were characterized by single-crystal X-ray diffraction (SCXRD) and X-ray photoelectron spectroscopy (XPS) analytical techniques. The SCXRD and XPS analyses reveal that the obtained two-dimensional structures are rich in uncoordinated imine (-CH═N-) groups located on the skeleton of the salen-type organic ligand, which retain strong coordination ability with metal ions. On the basis of this unique feature, a highly dispersed CeO-supported Ni catalyst (Ni/CeO-CAS) with highly strong metal-support interaction was first synthesized via a coordination-assisted synthesis (CAS) method, which exhibits a much better catalytic activity in the hydrogenation of nitrobenzene than the traditional Ni/CeO-IWI catalyst prepared by incipient wetness impregnation (IWI). The origin of the improved catalytic activity of Ni/CeO-CAS as well as the role of Ni@Ce-Hsalen was revealed by using diverse characterizations. On the basis of the comparative characterization results, the superior catalytic performance of Ni/CeO-CAS to Ni/CeO-IWI could have resulted from the smaller and highly dispersed Ni nanoparticulates, the intensified Ni-CeO interaction, the enhanced NiO reducibility, and the higher concentration of oxygen vacancies, favoring the H dissociation and adsorption of the nitrobenzene reactant. The Ni/CeO-CAS catalyst also exhibits high catalytic performance for reduction of diverse nitroarenes to their corresponding functionalized arylamines. We anticipated that this coordination-assisted strategy may provide a new way for preparing other highly oxide-supported catalysts with potential applications in various catalytic reactions.

No abstract

No abstract