Preparation And Photocatalytic Performance Of Carbon Nitride Composites

Currently,with the rapid development of global industrialization,environmental pollution and energy crisis are impacting on people's production and life,as well as the harmonious development of human and nature.Ever since 1972,when Fujishima and Honda had reported the water splitting breakthrough,photocatalytic technology came into people's visions.Photocatalyst could decompose the environmental pollutants or convert light into chemical energy through a series of the REDOX reaction under solar light.This opens up a new way for solving environmental and energy problems.Carbon nitride?g-C₃N₄?,an innovative visible light driven photocatalysts,with an adjustable band gap structure,high thermal stability,high chemical stability,interesting electronic properties,and environmental protection,energy-saving,has become one of the hot points in the field of photocatalysis.However,g-C₃N₄ is suffered from small specic surface area and high recombination efficiency of photoinduced electron-hole pairs,which results in low photocatalytic efficiency,and thus limiting the large-scale application of g-C₃N₄.In this work,the g-C₃N₄ has been stripped into a single-layer structure of 2D GL-C₃N₄,in order to obtain a large specific surface area and good performance.And using 0D,2D materials combining with that forming 0D/2D,2D/2D structure materials,in order to obtain more surface area and high coupling heterointerfaces extent,in which could effectively facilitate separation/transfer of photoinduced electron-hole pairs,and thus improve the catalytic performance of GL-C₃N₄ further.The main content of this paper is as follows:?1?PbS/GL-C₃N₄ composite was obtained by combining PbS quantum dot with GL-C₃N₄ by agitation.The chemical composition,structural information,microstructure and optical properties of the synthesiszed photocatalysts were analyzed by XRD,FT-IR,XPS and so on.And the visible-light-driven photocatalytic activities of PbS/GL-C₃N₄ composites were evaluated by the degradation of RhB.The 1%PbS/GL-C₃N₄ composite showed higher photocatalytic degradation efficiency under visible light irridation than GL-C₃N₄,it was about 1.85 times of GL-C₃N₄.At the same time,the possible photocatalytic mechanism of RhB degradation over PbS/GL-C₃N₄ composite materials was also proposed.It confirmed that O₂^·-,·OH and holes played important role for the photocatalytic degradation of RhB.?2?The SnO₂/GL-C₃N₄ photocatalysts were synthesiszed via the in situ growth of GL-C₃N₄ in the presence of SnO₂ nanosheets.The chemical state of elements,microstructure and grain morphology of the samples were analyzed by XRD,XPS,TEM and others.The visible-light-driven photocatalytic activities of SnO₂/GL-C₃N₄composites were evaluated by the degradation of RhB.It has been found that the optimal photocatalytic activity over 25%SnO₂/GL-C₃N₄ was almost 8 times higher than that of SnO₂ precursor,and 2.5 times as high as that of GL-C₃N₄ precursor,respectively.At the same time,the possible photocatalytic mechanism of RhB degradation over SnO₂/GL-C₃N₄ composite materials was also proposed.It confirmed that O₂^·-was the main active specie.?3?The MoO₂/GL-C₃N₄ composite was synthesiszed by an environmentally friendly solvothermal method.The crystal structure,microstructure and photoelectric property of samples were analyzed by XRD,XPS,TEM,EIS and so on.And the visible-light-driven photocatalytic activities of MoO₂/GL-C₃N₄ composites were evaluated by the degradation of RhB.It has been found that 2%MoO₂/GL-C₃N₄composite showed the optimal photocatalytic activity,it was about 2.55 times of GL-C₃N₄.At the same time,the possible photocatalytic mechanism of RhB degradation over MoO₂/GL-C₃N₄ composite was also proposed.It confirmed that both holes and O₂^·-were main active species in RhB photocatalytic degradation.