Synthesis Of Graphite-like Carbonitride Based Materials And The Photocatalytic Activity For Nitrogen Oxides

In recent years,rapid industrialization and civilized processes have brought serious environmental problems,especially air pollution caused by excessive emissions of NOx,SOx,VOCs and PM2.5,which seriously affected the natural ecological environment and human health and safety.To improve this situation,people have devoted to finding effective solutions,among which the photocatalytic technology has attracted more and more people's attention because of its high efficiency,and low risk of secondary pollution,and durability.This technology can effectively convert solar energy into highly oxidative radicals,which can oxidize nitrogen oxides in the air to nitrate,.Graphite-like carbon nitride polymer?PCN,which also known as g-C₃N₄?due to its easy synthesis,environmental friendliness,high specific surface area,good chemical stability,layered structure and it is favored by a narrow band gap excited by visible light.Although significant progress has been made in the development of carbon nitride-based photocatalysts,there are still some challenges that limits their application,such as the high recombination rate of electron-hole pairs,and lower utilization of visible light.To address these issues,theresearchers have then developed series of modification methods on carbon nitride,such as the heteroatom doping and morphology structure regulation to narrow band gap or form a new energy level in band gap.In this paper,carbon nitride is used as the substrate,and two new methods are used to modify it.The first uses it to build heterojunctions with other semiconductors and maximizes the interaction of the two phases.The second method utilizes a one-step method to simultaneously introduce defects and surface acid modification,which fully reduces the recombination rate of electron-hole pairs in the photocatalyst,prolongs the lifetime of photogenerated carriers,and improves the activity of photocatalytic degradation of NO by visible light.The first method achieves uniform distribution of N-TiO₂ nanoparticles on the carbon nitride layer and controllable number of heterojunctions.The second method with the treatment of sodium borohydride can produce N defects as well as borate modifications,and the number of defects and borate is also controllable.Finally,we analyzed the phase structure of the catalyst by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,UV-visible diffuse reflectance spectroscopy?UV?,photoluminescence spectroscopy?PL?and other conventional analytical instruments.In addition,we used in situ diffuse reflectance infrared Fourier transform spectroscopy to detect the transfer path of intermediates and final products during the reaction,and explained the oxidation mechanism of NO.In general,our work can effectively optimize the photocatalytic performance of PCN-based materials and have the potential to be scaled up for air pollution control.