Synthesis Of Iron-based Material Their Application In Electrocatalytic N₂ Reduction Reaction

As a crucial activated nitrogen feedstock for agricultural fertilizers,NH₃ play a key role of the growth of the human population and the ecology of the planet.As the dominant route for industrial-scale NH₃ production from N₂ and H₂,the Haber-Bosch（H-B）process suffers from large energy consumption and heavy serious greenhouse gas emission.Electrochemical N₂ reduction in aqueous media is considered as a promising alternative for carbon-free and but NH₃ production at ambient conditions.Although it tackles the energy-and H₂-intensive operations by the H-B process,this method is still challenged with N₂ activation and effective electrocatalysts for the N₂ reduction reaction（NRR）are a prerequisite.In this dissertation,we focused on the preparation of iron-based nanoarray material and their application in electrocatalytic N₂ reduction reaction（NRR）.The main points of research results are as follows:1.F-doped FeOOH nanorod（β-FeO（OH,F））were prepared by one-step hydrothermal method.When tested in 0.5 M LiClO₄,suchβ-Fe O（OH,F）nanorod obtains optimal NH₃ yield(42.38μg h^–1 mg^–1_cat.)and FE（9.02%）,much higher that those of pristineβ-FeOOH(10.01μg h^–1 mg^–1_cat.,2.16%).Density functional theory calculations reveal that the enhancement in activity originates from the lower reaction energy barrier（0.24 eV）than that ofβ-FeOOH（0.59 eV）.2.We report that FeOOH quantum dots decorated graphene sheet acts as a superior catalyst toward enhanced electrocatalytic N₂ reduction to NH₃ under ambient conditions.The NRR activity of FeOOH QDs-GS was studied.In 0.1 M LiClO₄,this hybrid attains a large NH₃ yield rate and a high Faradaic efficiency of 27.3μg h^–1 mg^–1_cat.and 14.6%,respectively.It also shows strong durability during the electrolytic process.3.We obtained two kinds of phosphates by controlling the content of phosphorus:FeP₂ nanoparticles-reduced graphene oxide hybrid（FeP₂-rGO）and FeP-rGO.It is found that phosphorus plays an important role in regulating NRR activity of iron-based catalysts.FeP₂-rGO attains large NH₃ yield of 35.26μg h^–1 mg^–1_cat.and a high Faradaic efficiency of 21.99%in 0.5 M LiClO₄,outperforming FeP-rGO hybrid(17.13μg h^–1 mg^–1cat.;8.57%).Theoretical calculations reveal that FeP2 possesses decreased catalytic activity for hydrogen evolution reaction,higher N₂ adsorption energy,and larger number of active sites than FeP.