In-situ Intercalation To Prepare Sheet-layer Iron-based Metal Oxide/C₃N₄ And Photocatalytic Performance

The continued growth of the world population has greatly increased the demand for agricultural and industrial products,which has inevitably led to a rapid increase in the emission of organic pollutants into the environment.Photocatalytic degradation of pollutants is considered one of the most economical and environmentally friendly strategies.It uses photocatalysts to convert light energy into chemical energy,generate free radicals,and then oxidize organic wastewater into harmless substrates.The typical photocatalyst carbon nitride（C₃N₄）is a layered,non-toxic polymer,it has good energy band structure,high stability and low cost.However,in practical applications,it is often restricted by small specific surface area,low light utilization,poor electrical conductivity,and fast photoinduced electron-hole recombination.Combining it with a semiconductor to construct a heterojunction can effectively improve these problems.In this paper,a simple intercalation and exfoliation strategy is developed,in which iron series metal oxides and C₃N₄ are combined to construct heterogeneous structures,which can be used as efficient photocatalysts for degradation of organic pollutants.The specific research contents are as follows:1.Layered C₃N₄ precursor was synthesized by melamine water heat treatment,and Co²⁺ions were inserted into the interlayer of the precursor by vacuum assisted interlayer process.Subsequently,the C₃N₄ precursor was dissected into nanosheets,and Co₃O₄ nanoparticles with a size of about 15 nm were formed at the same time of in-situ thermal condensation to obtain the heterostructure of Co₃O₄/C₃N₄.Its high specific surface area exposes more active sites on the surface.The specific surface area of the heterojunction is about 21 times that of the bulk C₃N₄,which exposes more active sites on the surface.The Type-II transfer mechanism between Co₃O₄ nanoparticles with oxygen vacancy and C₃N₄ can effectively separate photogenic electron-hole pairs and improve electron mobility.The photocatalytic degradation rate of methylene blue by heterojunction reached 99.5%,and it had excellent cycling stability.Studies have shown that·O₂^-is the main active oxidant in the degradation process.2.The Fe₂O₃/C₃N₄ heterojunction photocatalyst was prepared using the same strategy,in which the size of Fe₂O₃ nanoparticle was about 8 nm.Compared with the lamellar structure C₃N₄,the visible light range of the heterojunction increases and the charge transfer resistance decreases,and the Type-II photogenic charge transfer mechanism can efficiently separate the photogenic electron-hole pairs.The degradation rate of heterojunction nitrobenzene was 69%.After the introduction of H₂O₂ into the reaction system,the degradation rate of nitrobenzene was increased to 93%by photocatalysis-Fenton.Different scavengers were further added to the reaction to prove that the active substances were·OH and·O₂^-.