The Investigation Of Optoelectronic Properties Of Graphitic Carbon Nitride And Its Application

Graphite-like carbon nitride?g-C₃N₄?,a two-dimensional polymeric semiconductor material with outstanding semiconductor characteristics,suitable electronic energy band structure and excellent physicochemical stability,has been attracted widespread attention recently as a novel inorganic photoelectron material in the fields of photo?electric?-catalysis,photoelectric conversion,analytical sensing,fluorescent marking,light emitting devices and so on.Upon the visible light,g-C₃N₄ has the prominent advantages of high-efficiency photocatalytic hydrogen evolution,which has promoted the development of tremendous functionalization strategies for further improvement of its photoelectric properties,aiming at an affordable clean energy future.Besides,these functionalization methods are expected to explore the newly disclosed properties of g-C₃N₄ for other potential application fields,which also benefit for the systematic study on its electronic structure and optical properties.Based on the conceptions mentioned above,the purpose of this dissertation is to explore the new functionalization methods to realize the systematically manipulation of its electronic structure and photoelectric performance,enhancing the efficiency in energy conversation and broadening its applications in other fields,which could enrich the research of the g-C₃N₄ related materials.Controlled morphology modulation of graphene carbon nitride is successfully realized from bulk to 3D loose foam architecture via the bubble template method.The photocatalytic performance of the products toward RhB decomposition and hydrogen evolution is significantly enhanced with the morphology optimization while its excellent optoelectronic properties are maintained simultaneously.The 3D loose foam g-C₃N₄ produced by blowing effect is comprised by spatially scaffolded few-atom-layer interconnected flakes with the large specifc surface area,as supporters to prevent agglomeration and provide a pathway for electron/phonon transports.The ultrathin g-C₃N₄ interconnected flakes with layer controlled by heating rate could be facilely obtained by this method,thus overcoming the drawbacks?low efficiency and time-consuming?of a traditional top-down approach.Additionally,the layer control mechanism of 3D hierarchical structure has been explored by means of bubble growth kinetics analysis and the density functional theory calculations?DFT?.In addition,polymeric g-C₃N₄ with controllable photoluminescence emission wavelength in the whole visible light range?450-650 nm?have been synthesized through the one-step molecular doping during the thermal condensation process of g-C₃N₄ conjugated framework,which open up its application beyond the conventional catalysis scopes.By adjusting the doped content of hetero-molecules,the modified g-C₃N₄ in which the optical properties could be controlled according to the demand of practical applications,could be facilely and largely obtained.It overcomes the limitation of the narrow adjusting range of conventional g-C₃N₄ on optical properties and makes it more promising for applications in solid-state photoconductive devices,illumination displays,biological probes and so on.This work has systematically studied the effect of doped molecule on the?-conjugated system of g-C₃N₄,and the tunable luminescence mechanism has been proposed.At last,full-color LED device have successfully fabricated using g-C₃N₄-based materials,and white-light-emitting diodes?WLED?of g-C₃N₄have firstly reported in our work.