Synthesis Of Iron-based Nanocatalysts For Photocatalytic Water Oxidation

Inspired by the natural photosynthesis of green plants and some other microorganisms, the using and development of solar energy, which is recognized as the most promising solution to address the environmental and energy crisis. The water oxidation, which is half reaction of photocatalytic water splitting process, has been considered the most challenging step. In the oxygen evolution reaction?OER?, the production using solar energy input has largely been limited by sluggish kinetics. Therefore, the fast, efficient and cheap water oxidation catalysts have been developed with the intention of lowering the energy barrier to generate oxygen efficiently. So far, Fe-based nanomaterials have received considerable attention. Not only iron is an important member of the transition metal, but also it possesses of unique character. For instance, it is abundant, cost effectiveness, and has metal active sites. By virtue of their inherent physicochemical properties, Fe-based nanomaterials are widely used in a variety of applications such as catalysis, chemical sensors, and water treatment. In this paper, firstly, flower-like FeS₂ nanomaterials are synthesized by a two-phase solvothermal method. Secondly, three types of Fe-based metal organic frameworks?MOFs? and their aminofunctionalized derivatives have been fabricated by solvothermal method and hydrothermal method. Thirdly, spindle-like Fe₂ C nanomaterials are prepared from nanoscale MIL-88B-NH₂?Fe? template. At last, these Fe-based nanomaterials are developed as water oxidation catalysts.Firstly, by employing FeSO₄?7H₂O as the precursor and S as sulfur source, flower-like pyrite FeS₂ nanomaterials were successfully obtained by a facile twophase solvothermal method. The phase composition and morphology of the asobtained products were influenced by various NaOH concentrations and the sulfur dosage. Moreover, FeS₂ have been directly applied to photocatalytic oxygen evolution reaction under visible light irradiation and the catalysts possessed excellent water oxidation activity in the third runs.Secondly, three types of Fe-based MOFs and their aminofunctionalized derivatives were explored as water oxidation catalysts. MOFs have emerged as a promising class of porous materials with very large specific surface area and ultrahigh porosity. Among the as-obtained MOFs, MIL-101?Fe? possesses a higher current density and earlier onset potential and exhibits excellent visible light-driven oxygen evolution activity than the other Fe-based catalysts.At last, we develop carbonized nanomaterials?Fe₂C? derived from nanoscale MOFs?MIL-88B-NH₂?Fe??, as water oxidation catalysts. This Fe₂ C nanomaterials show greatly enhanced performance of O₂ evolution. In addition, the magnetic nanomaterials are simply and efficiently removed from reaction mixtures with an external magnetic field. The results showed that the as-prepared Fe₂ C magnetic nanomaterials have emerged as ideal catalysts.