晶面协同NaF–TiO_(2)/rGO的制备及其光催化性能

Preparation and photocatalytic performance of NaF–TiO_(2)/rGO with facet synergy

为解决二氧化钛(TiO_(2))光生载流子寿命短的问题,以钛酸四丁酯、氟化钠和石墨粉为原料,采用水热法制备了NaF-TiO_(2)/rGO复合材料,通过透射电镜(TEM)、X射线能谱分析(EDS)、X射线衍射(XRD)、光致发光光谱(PL)、紫外漫反射光谱(UV-Vis)对复合材料的微观形貌、物相组成、晶型、荧光强度等特性进行了表征,并以降解罗丹明B(RhB)测试其光催化活性及降解机理.实验结果表明,制备得到的产物主要为{001}、{101}晶面协同的锐钛矿相TiO_(2)并均匀分布于rGO表面,NaF与rGO的加入可有效降低其电子-空穴对的复合速率以及带隙宽度从而提高光催化活性.在最佳制备条件下,催化反应80 min后对1×10^(-5)mol·L^(-1)罗丹明B(RhB)溶液的降解率可达99.8%,降解速率常数(0.0448 min^(-1))是NaF-TiO_(2)的1.67倍,且复合材料的催化性能随其投加量的增大先加强后保持稳定,pH适用范围为3~11;自由基猝灭实验结果表明,在光催化降解过程中,起主要作用的活性物质是·OH和h^(+).

TiO_(2)has been widely studied because of its excellent photocatalytic properties but still has defects,such as the short lifetime of the photogenerated carrier.To solve these problems,a novel NaF-TiO_(2)/rGO composite has been successfully synthesized using the hydrothermal method.The photocatalyst complexes were characterized using transmission electron microscope(TEM),energy dispersive spectrometer(EDS),diffraction of X-rays(XRD),photoluminescence spectroscopy(PL),and ultraviolet-visible spectroscopy(UV-Vis).This paper investigates the effects of hydrothermal temperature,hydrothermal time,rGO content,and NaF content on the photocatalytic activity of the NaF-TiO_(2)/rGO composite,and the photocatalytic activity is evaluated using the photocatalytic degradation of RhB under fluorescent lamp illumination for approximately 80 min.The TEM analysis and identification results indicate that rGO can be incorporated into TiO_(2)to form a heterogeneous structure.The XRD results show that no heterophase formation occurs in the prepared NaF-TiO_(2)/rGO composite,and the NaF-TiO_(2)/rGO composite on the rGO surface does not cause the crystal shape change of the anatase phase.The PL results indicate that the main products are TiO_(2)with{001}and{101}facet synergy,and adding rGO effectively reduces the electron-hole pair recombination rate.The UV-Vis results show that the band gap energy of TiO_(2)is reduced by introducing NaF and further reduced after rGO is combined,thereby enhancing the photocatalytic activity and efficiency of TiO_(2).Compare and analyze RhB degradation using different factor systems and determine the best synthesis process for preparing composite materials at a hydrothermal temperature of 100℃,a hydrothermal time of 10 h,an rGO content of 0.3%,and a NaF content of 30%.The composite material had the best photocatalytic activity.The photocatalytic test results indicate that NaF-TiO_(2)/rGO synthesized using the hydrothermal method has a better light absorption efficiency.The samples have a better RhB degradation rate under simulated solar irradiation.The RhB degradation followed pseudo-first-order reaction kinetics with a rate constant of 0.0448 min^(-1),which is 1.67 times that of NaF-TiO_(2).The RhB degradation rate over 80 min reached 99.8%,increasing first and then remaining constant with increasing NaF-TiO_(2)/rGO dosage.Additionally,NaF-TiO_(2)/rGO has good catalytic activity in the pH range of 3-11.The results of free radical capture showed that all three kinds of free radicals participated in RhB photocatalytic degradation,and the main active species in the reaction system should be·OH and h^(+).