Synthesis And Properties Of Carbon Nitride-based Nano Catalysts

This article mainly aims to modify the photoelectrochemical performance of layered graphitic carbon nitride materials by adjusting the ratio of carbon to nitrogen,constructing a heterogeneous structure,and adjusting the microscopic morphology.The main contents are as follows:Controllable synthesis and photocatalytic properties of ultra-thin carbon nitride(g-C₃N₄)nanosheets.The thickness of the g-C₃N₄ nanosheets can be optimized by adjusting the precursors used in the preparation process and the polymerization temperature.Furthermore,the prepared nanosheets were subjected to thermal stripping and ultrasonic thinning treatments,the influence of parameter changes such as processing time on the properties of the product was studied,and a photocatalytic material with excellent properties was obtained,and the relationship between the microstructure and the properties was discussed.The results of atomic force microscopy test shows that increasing the polymerization temperature during the synthesis of carbon nitride can achieve thermal peeling,effectively reducing its thickness to few nanometers.Through further thinning,ultra-thin g-C₃N₄ with a thickness of 1 nm,nearly 3layers of molecules can be obtained.The experimental results of photocatalytic degradation of rhodamine B and photocatalytic water splitting to produce hydrogen show that the reduction of the number of carbon nitride layers is beneficial to the acceleration of the photocatalytic reaction.The degradation rate of sample 750DCN reached 93%in 15 minutes,and the catalytic rate of this sample to hydrogen can reach 1136?mol·g^-1·h^-1.Controllable synthesis and photocatalytic properties of graphitic carbon nitride and crystalline/amorphous g-C₃N₄ homojunctions(H-LCN)with different ratio of carbon to nitrogen.In order to adjust the degree of crystallization,and then adjust the carbon to nitrogen ratio,controlling the polymerization temperature,selected the optimal polymerized temperature,and finally obtained a crystalline/amorphous g-C₃N₄ homojunction.The experimental results proved that the effect of photocatalytic degradation was hugely improved.Taking this structure as a substrate and iron and nickel oxides was loaded.The HER performance of the sample is improved,the overpotential is 672 mV when the current density reaches 50 mV cm^-2,and the Tafel slope is 74 mV/dec.By compared the differences in electrochemical performance,combined high-resolution transmission electron microscopy and band gap analysis,the principle of structural evolution was discussed.Study on controllable synthesis and electrochemical performance of Co-doped carbon nitride nanotubes.Carbon nitride-based precursors will decompose at high temperatures,while carbon and nitrogen elements will be enriched and rearranged on the surface of transition metals when the transition metals such as iron,cobalt and nickel,exist.Subsequently,the displacement occurs under stress to form nanotubes.This process was discussed in conjunction with scanning electron microscope images.Furthermore,taking the nitrogen element on the nanotube as an anchor point,molybdenum disulfide(MoS₂)nanosheets were anchored and epitaxially grown to obtain a one-dimensional MoS₂/N-CNTs composite material.This structure has good electrocatalytic hydrogen production performance(?=468 mV,b=52 mV/dec).A series of electrochemical tests had proved the unique role of nitrogen in the process of oxygen reduction reaction and hydrogen reaction.In addition,an attempt was made by doping sulfur during the preparation of nanotubes,and a one-dimensional structure of Co S₂/Co/N-CNTs was obtained.Experimental results shown that this structure greatly improves the activity of the sample for hydrogen production by electrolysis of water in alkaline solution(?=280 mV,b=57 mV/dec).These results further enrich the research and application prospects of carbon nitride-based nanomaterials.Study on synthesis and properties of g-C₃N₄ nanocomposites supported by h-BN quantum dots.A hexagonal boron nitride(h-BN)quantum dots modified g-C₃N₄ nanocomposite material was obtained by adjusted the environmental composition of the g-C₃N₄ nanosheet suspension.At the same time,g-C₃N₄ was modified with large-size h-BN nanosheets.Tests show that carbon nitride modified by boron nitride quantum dots exhibits high activity in degrading antibiotics,and the degradation rate can reach 50.2%after 90 minutes of photocatalytic reaction.The main active substances are photogenerated holes and superoxide radicals.Comparing its degradation effects on antibiotics,combining a series of photochemical test and analysis methods such as scanning electron microscopy images,specific surface area and reaction kinetics,the reasons for the improvement of its performance are discussed.