Preparation And Photocatalytic Performance Of Bismuth Halide Oxide And Its Composites

With the rapid development of the world economy and industry,environmental pollution and energy crisis have seriously threatened the living environment and sustainable development of living organisms.Visible light driven semiconductor photocatalysis technology is a very potential technology,which has been widely paid attention to solve environmental pollution and alleviating energy crisis.The development of environmentally friendly,cheap and efficient visible light catalytic photocatalysts remains one of the major challenges in the field of photocatalysis.Bismuth halide BiOX(X=Cl,Br,I)is a visible light catalyst capable of degrading organic pollutants.It has been widely studied for its unique layered structure,excellent photoelectric propertie and high chemical stability.However,the photocatalytic efficiency of pure BiOX is not optimistic due to its defects of easy recombination of photogenerated electron holes.In this work,some different methods were used to prepare bismuth halide oxide and composites to improve the photocatalytic performance of bismuth halide oxide.(1)Biomass waste(withered typha grass)was used to fabricate nitrogen-doped hierarchical carbon(NHC)by an one-step carbonization route.Then NHC provided a good carrier to load the BiOl semiconductor materials by a green simple co-precipitation method,after adding NaOH solution,the irregular microspheres BiOI/NHC was gradually etched by OH-to form the tremella-like Bi4O5I2/NHC.The well-defined tremella-like Bi405I2/NHC invested adequate interface and high particular surface range(SHET:66 m2 g-1),which is higher than pure BiOI(22 m2 g-1)and Bi4O5I2(17 m2 g-1).Multiple synergistic effects,such as high SBET can give more dynamic destinations,the special tremella-like structure can assimilate more reflected occurrence light of other nanosheets,low I content can increase the conduction/valence band gap of semiconductor materials and NHC can act as an electron acceptor,making as-prepared Bi4O5I2/NHC composite ideal candidates for photocatalysis.The degradation rate of Bi4O5I2/NHC reaches up to 87.4%of methyl orange in 2 hours,which is about 2 times higher than BiOI and Bi4O5I2.(2)It is usually to prepare bismuth oxide and its derived composites by liquid phase strategy,which will produce waste liquid and may pollute the environment.In this work,bismuth nitrate pentahydrate,potassium chloride,graphene process,the BH4K can reduce GO to RGO,which has boxide(GO)and BH4K were mixed and ground without solvent to synthesize BiOCl/reduced graphene oxide(RGO)composite in a very short time(15 min).During the synthesis etter electrical conductivity to transfer the photogenerated electrons timely and improves the separation of the photoelectric carrier effectively.Meanwhile,oxygen vacancy were introduced due to the reduction of BH4K.Therefore,the photocatalytic property of BiOCl/RGO has been greatly improved,which has 6 times degradation rate than pure BiOCl.Mechanism studies have shown that h+,·O2-and ·OH work simultaneously in the process of degrading pollutants.(3)A high-efficiency photocatalytic BiOC1 material with visible light absorption range was successfully prepared by one-pot molecular self-assembly and particle recrystallization method at room temperature.In the process of crystal growth,tartaric acid,as a structure control agent,gradually transforms the repacked two-dimensional nano-sheet-like BiOC1 into a hierarchical structure composed of petal-like nano-sheets through hydrogen bonding.Besides,the acid etching of organic carboxylic acid on the crystal surface increases the number of micropores and mesopores,thereby the reaction interface.The thioureav(TU)molecules adsorbed on the BiOC1 surface with strong electronic effect introduce oxygen vacancies(OVs)under the condition of low oxygen content.The synergistic effect of hierarchical structure and OVs reduces the recombination of photogenerated carriers,butabsorbs more O2 and OH-to generate a large number of superoxide radicals(·O2-)and hydroxyl radicals(·OH)effectively.The photocatalytic performance of the synthesized BiOC1 material has been significantly improved,and it can effectively degrade 94.15%of rhodamine B(RhB)within 20 minutes.At the same time,it also has good degradation ability to tetracycline,ciprofloxacin and methyl orange.