单斜BiVO_4可见光催化降解甲基橙的形貌效应

Morphology-Dependent Photocatalytic Performance of Monoclinic BiVO_4 for Methyl Orange Degradation under Visible-Light Irradiation

以硝酸铋和偏钒酸铵为无机源,NaOH为pH值调节剂,三嵌段共聚物P123为表面活性剂,采用醇-水热法制备了多种形貌的单斜BiVO4.利用X射线衍射、N2吸脱附、扫描电子显微镜、X射线光电子能谱和紫外可见光漫反射等技术表征了其物化性质,并考察了这些BiVO4样品在可见光照射下降解甲基橙的催化活性.结果表明,表面活性剂和溶液pH值对所得BiVO4产物的粒子形貌影响很大.在醇-水热温度为180oC,pH值为2,7或10时,可分别制得多孔球状、花状和片状BiVO4;而采用P123作表面活性剂,在醇-水热温度为180oC且pH为2时可制得棒状BiVO4.BiVO4样品粒子形貌的不同导致它们的比表面积、表面氧空位密度和(040)晶面暴露率不同,其中以棒状BiVO4样品具有最高的比表面积、氧空位密度和(040)晶面暴露率以及最低的带隙能,使其对甲基橙降解表现出最好的光催化活性.可以认为,BiVO4样品对甲基橙的光催化降解反应活性存在形貌效应,棒状形貌有利于提高BiVO4的光催化性能.

Monoclinic BiVO4 with multiple morphologies were fabricated using the alcoho-hydrothermal strategy with bismuth nitrate and ammonium metavanadate as inorganic sources,NaOH for pH adjustment,and the triblock copolymer P123 as a surfactant.The materials were characterized by X-ray diffraction,nitrogen adsorption-desorption,scanning electron microscopy,X-ray photoelectron spectroscopy,and ultraviolet-visible diffuse reflectance spectroscopy.The photocatalytic performance of the BiVO4 samples was evaluated for the degradation of methyl orange （MO） under visible-light irradiation condition.The results showed that the surfactant and pH had a significant influence on the particle morphology of the BiVO4 product.Porous spherical,flower-like,and sheet-like BiVO4 were fabricated at an alcoho-hydrothermal temperature of 180 °C and at a pH of 2,7,or 10,respectively,whereas rod-like BiVO4 was obtained in the presence of P123 at an alcoho-hydrothermal temperature of 180 °C and at a pH of 2.The difference in BiVO4 particle morphology led to differences in surface area,surface oxygen vacancy density,and （040） crystal plane exposure.Among the four BiVO4 samples,the rod-like sample had the highest surface area,surface oxygen vacancy density,and （040） crystal plane exposure,and the lowest bandgap energy resulting in it having the best photocatalytic activity for MO photodegradation.It can be concluded that a morphological effect is responsible for the photocatalytic performance and the rod-like morphology seems to favor an enhancement in the photocatalytic performance of the BiVO4 material.