Unravelling The Roles Of Fe-based Metal-Organic Frameworks In Visible-Light-Driven Hydrogen Evolution

Metal-organic frameworks(MOFs),a class of hybrid materials built from the coordination of limitless choice of metal ions or clusters with organic ligands,have exhibited intrinsically ordered three-dimensional(3D)structures that gave rise to a myriad of potential applications such as gas adsorption and storage,sensing,catalysis,separation,and nonlinear optical devices.One latest development is to utilize MOFs as precursors for the fabrication of other materials like metal oxides,which have found broad applications in the field of energy and catalysis.In this thesis,we have synthesized Fe based MOFs(Fe-MOFs)via microwave assisted method,and employed them as precursors for the fabrication of photo catalyst for visible-light-driven hydrogen evolution.We systematically investigated the factors influencing the efficiency of hydrogen production,such as the metal cluster center,the three-dimensional structure of MOFs and the co-catalyst,until eventually unraveled the roles of Fe-MOFs in photocatalytic water splitting.This work is composed of the following sections:1.Introduction to the background of MOFs and literature review on MOFs photocatalysis.2.The construction of a series of Fe(?)-based MOF structures(Fe-MOFs)with different morphologies and sizes via microwave assisted syntheses by controlling solvent constitution.TEM,SEM,XRD and various spectroscopic methods were applied to thoroughly characterize the as-synthesized products.3.We then explored the H2 evolution capability of these Fe-MOFs,which exhibited a rapid rate of 13000 ?mol/g and high quantum efficiency of 1.17%,significantly surpassing other MOF structures.We tentatively concluded the Fe-MOFs acted as precursors for the fabrication of water splitting photocatalyst through comparing the structural change of Fe-MOFs before and after photocatalysis,and a systematic investigation of the influence of the morphologies and sizes,the metal cluster centers,and the 3D structures of MOFs on H2 evolution efficiency.4.The structure and composition of the photocatalyst obtained via MOFs decomposition were thoroughly investigated.The catalyst turned out to be micro-nano materials consisting of Fe,C and other elements,with a tentatively deduced composition of FeO3.30 C0.24 H1.15.