Preparation And Performance Study Of Ternary Composite Photocatalyst Based On GC₃N₄

In the past decades,with the rapid development of industrial,food and other fields,water environmental pollution has bacome one of the most serious problems threatening the development of human society and environment.To prevent this situation from getting worse,semiconductor photocatalytic technology has been proposed by researchers with high expect.Semiconductor photocatalysis technology is an effective method to effectively convert solar energy into chemical energy and prevent environmental problems from worsening.Among a large number of semiconductor photocatalytic materials,the composite photocatalyst based on g-C₃N₄ began to widely enter the vision of researchers.In recent years,it has also been widely used in the fields of photocatalytic degradation and photocatalytic hydrogen evolution.Different from the traditional g-C₃N₄photocatalysts,the mesoporous g-C₃N₄（denoted as Meso-g-C₃N₄） photocatalysts formed by modification exist more surface active sites and have narrower energy band gaps,which are favorable for enhancing the photocatalytic performance in visible light.However,both the single g-C₃N₄ and mesoporous g-C₃N₄ photocatalytic materials are still limited the widely use in the field of photocatalysis due to their rapid charge recombination rate and narrow spectral absorption range.In this case,combining g-C₃N₄ and Meso-g-C₃N₄ photocatalytic materials with other semiconductor photocatalysts to form new heterostructure is an effective method to improve the photocatalytic performance.Therefore,in order to prepare a composite photocatalyst based on g-C₃N₄ with excellent performance,two ternary photocatalysts g-C₃N₄/Ni₂P/Ni（PO₃）₂ and ZnS/Bi₂S₃/Meso-g-C₃N₄ were prepared by calcination,hydrothermal and template calcination methods.Under the visible light irradiation the as-prepared ternary heterojunction materials can effectively degrade water both of them show excellent stability.（1）The ternary heterojunction photocatalyst g-C₃N₄/Ni₂P/Ni（PO₃）₂ was successfully prepared through calcination and hydrothermal method.The Ni₂P and Ni（PO₃）₂ composite nano materials are adhered to the surface of g-C₃N₄ nanosheets and effectively formed heterojunction structures.Under the condition of visible light irradiation,the degradation rate of methyl orange over the as-prepared composite photocatalysts are reached above 99%after 120 min,and the hydrolytic hydrogen production efficiency reached 508.3 mol h^-1g^-1.This mainly due to the synergistic effect between Ni₂P,Ni（PO₃）₂ and g-C₃N₄ and the specifical heterojunction structure,which can effectively increase the light absorption and accelerate the separation of photogenic carriers,thus to enhance the photocatalytic activity.（2）ZnS/Bi₂S₃/Meso-g-C₃N₄ ternary heterojunction photocatalyst was successfully prepared via the hydrothermal and template-calcination methods.ZnS and Bi₂S₃ spheres are obtained by simple hydrothermal synthesis and attached to the surface of g-C₃N₄ nanosheets to form heterojunction structures.Under the condition of visible light irradiation,the degradation rate of methyl orange in the prepared composite photocatalysts are reached 99% after 120 min,and the hydrogen production reached 663.3 mol h^-1g^-1.This is mainly due to the synergistic effect between ZnS,Bi₂S₃ and mesoporous g-C₃N₄ amd their heterojunction structure,which can effectively increase the absorption of light and accelerate the separation of photogenic carriers,thus to enhance the photocatalysis activity.