The Synthesis Of Basic Bismuth Nitrates Photocatalysts And Studies Of Their Photocatalytic Activities

It is one of the most important technologies to solve the environmental pollution and energy crisis via photocatalysis to degrade pollutants and product hydrogen.Bismuth compounds have received intensive attention due to their rich raw materials,non-toxicity or hypotoxicity and good response to visible light.In recent years,basic bismuth nitrates have been used as photocatalysts due to their variety and toxicity.In this work,basic bismuth nitrates were synthesized via hydrothermal method or room temperature hydrolysis method by using Bi?NO₃?3·5H₂O as the bismuth source.The photocatalytic performance and adsorption properties of as-prepared basic bismuth nitrates also had been studied.The major contents are as follows:?1?Unique flowerlike Bi₂O₂?OH??NO₃??denoted as BION?hierarchical microstructures assembled by ultrathin nanosheets were hydrothermally synthesized from incomplete hydrolysis of anhydrous bismuth nitrate?Bi?NO₃?₃?after adsorption of glacial acetic acid?HAc?.HAc-adsorbed Bi?NO₃?₃,used as a precursor,plays a crucial role in the formation of the unique flowerlike BION hierarchical microstructures.The hydrothermal temperature and reaction time also had great influence on the morphology of the products.The morphology of the sample prepared at 150 ? for 5 h was most uniform and it exhibited superior photocatalytic activity for rhodamine B?RhB?and crystal violet?CV?degradation.?2?Bi₂S₃/Bi₂O₂?OH??NO₃??denoted as BS-BION?composite was prepared by an in-situ ion exchange reaction between BION and aqueous sulfur sources solution such as Na₂S,thiacetamide and thiourea by adjusting the solution pH value with HCl.The BS-BION which was obtained by using thiourea?pH= 3?exhibited superior photocatalytic performance for RhB degradation under visible light irradiation.?3?Two basic bismuth nitrate,[Bi₆O₅?OH?₃]?NO₃?5·3H₂O?denoted as BION-5N?and[Bi6O6?OH?2]?NO3?4-2H2O?denoted as BION-4N?,were obtained at room temperature in the existence of 2-methoxyethanol?2ME?with a pH control.The composition and morphology of basic bismuth nitrate could be easily tailored by changing the variety and amount of bases like urea,hexamethylenetetramine?HMTA?,NaOH and NH3_·H₂O.Among those,BION-4N obtained with 40 mmol of HMTA exhibited superior photocatalytic activity for RhB degradation under UV light irradiation due to higher surface area.BION-5N obtained with 10 mmol of urea exhibited excellent adsorption performance for MO due to highly positively charged surface.