Functionalized Metal-Organic Frameworks for Catalytic Applications

Abstract

The development and design of efficient catalysts are essential for catalytic energy technologies, accompanied with the fundamental understanding of structure-property relationships of these catalysts. Metal-organic frameworks (MOFs), as the new class of promising catalysts, have been intensively investigated primarily in their fundamental electrochemistry and the broad spectrum of catalytic applications due to their structural flexibility, tailorable crystalline, and multi-functionality. In this work, we combine experiments and mechanism investigation to gain a fundamental understanding of how the surface property and the structure of MOFs affect their catalytic performance. With the aim of material design for MOFs catalysts, we developed two novel superhydrophilic and aerophobic metal-organic frameworks (AlFFIVE-1-Ni MOFs and FeFFIVE-1-Ni MOFs) used as electrocatalysts for the first time during oxygen evolution reactions (OER). Under the facilitation of hydrophilicity and aerophobicity, developed FeFFIVE-1-Ni MOFs electrocatalysts deliver optimal OER performance, better than that of the state-of-art RuO2 and referred NiFe-BDC MOFs electrocatalysts. Most importantly, the practical strategy demonstrated that the hydrophilic and aerophobic structure of MOFs does indeed deliver the optimal electrocatalytic performance.

With the aim of investigating the structural transformation process of metal-organic framework, we used a series of advanced characterization techniques to monitor the structure evolution and defects presence for post-heating treated UiO-66 MOFs. The structural and electronic features of UiO-66 MOFs were intensely studied in their hydroxylated, dehydroxylated, defected, and pyrolytic forms. Meanwhile, one concept about the framework situation, quasi-MOF (like a transition state, defined high activation along the structure evolution corresponding to the presence of many defects), was presented and demonstrated. Compared with pristine UiO-66 MOF, the Quasi-MOF with the presence of active defects showed enhanced catalytic activity on the Meerwein-Ponndorf-Verley reduction reaction, which offers an opportunity to understand the structure-property relationship along with the structure evolution process of UiO-66 MOFs.