Hierarchical MOF-74/Cu2O/Cu composite derived from metal–organic frameworks for the degradation of 4-nitrophenol

Abstract

Metal–organic frameworks (MOFs) are recognized as advanced functional materials and ideal sacrificial templates due to their high specific surface area, abundant active sites, well-organized framework structure, and diverse morphologies. However, single-component MOFs have been unable to meet the increasing application requirements. Herein, MOF-74 was used as a sacrificial template to synthesize a composite material, MOF-74/Cu₂O/Cu, by calcining hierarchical MOF-74 at 250 °C. A series of characterization techniques were employed to analyse the morphology, chemical components, and valence state of Cu in MOF-74/Cu₂O/Cu. The results revealed that MOF-74/Cu₂O/Cu inherits the hierarchical structure of the parent MOF-74, which is composed of nanosheets. Furthermore, some of the Cu²⁺ nodes were transformed into Cu₂O and Cu during the pyrolysis process of MOF-74, resulting in the formation of the multicomponent composite material MOF-74/Cu₂O/Cu. Considering its multicomponent and hierarchical structure, the catalytic performance of the MOF-based composite material was evaluated for degrading 4-NP in the presence of NaBH₄. Additionally, the presence of Cu₂O and Cu was found to effectively shorten the induction period for reducing 4-NP and enhance the catalytic rate. Moreover, MOF-74/Cu₂O/Cu presented improved catalytic performance in the degradation of the dyes MO and MB. This study proposes a facile approach for synthesizing multi-phase composites based on the incomplete pyrolysis of MOFs, aiming to advance the development of functional materials.