固相烧结法制备硫掺杂单斜晶型WO3及其光催化活性研究

Preparation and photocatalytic activity of sulfur-doped monoclinic WO3 by solid phase sintering

以硫脲为掺杂剂,采用固相烧结法将硫元素引入单斜晶型WO3光催化剂,克服了传统固相烧结法制备WO3粒径较大、光催化活性较低的问题,研究了硫掺杂比例对WO3光催化活性的影响.通过X射线衍射、扫描电子显微镜、紫外可见吸收光谱、X射线光电子能谱对催化剂进行分析,探究了硫元素提升WO3光催化活性的机理.光催化降解实验结果表明,不同硫掺杂WO3样品光催化降解罗丹明B的反应符合一级反应动力学方程,当ms∶mWO3为1.5%时,罗丹明B的降解效率达到90%,与未掺杂硫的WO3相比,其降解效率提高30%,第3次循环利用时降解效果依然可观,罗丹明B降解率达到82%,表明S-WO3具有较高的稳定性.综合表征结果表明,硫对WO3有显著地细化作用;硫能够降低禁带宽度,使低能量的电子发生跃迁;并能同步增加WO3中的氧空位,进一步促进电子-空穴的分离,从而提高光催化效率.但当ms∶mWO3超过1.5%时,过多的氧空位形成了新的复合中心,影响了电子空穴的分离,导致WO3催化活性降低.

Sulfur was doped into the monoclinic WO3,which overcomed the problem of large particle size and low photocatalytic activity of WO3 prepared by conventional the solid phase sintering method using thiourea as the dopant.The influence of sulfur doping on the photocatalytic activity of S-WO3 was investigated.The catalysts were characterized by XRD,SEM,UV-Vis and XPS method,and the amelioration effect of sulfur element on WO3 was discussed in detail.The results of Rhodamine B degradation experiments indicate that photocatalytic degradation of Rhodamine B in different sulfur-doped WO3 samples correspords to the first-order reaction kinetic equation.The degradation efficiency of 90%can be obtained under the sulfur doping ratio of 1.5%,which is improved by 30%compared to that using undoped WO3.And the degradation effect is still considerable in the third recycling,while the degradation rate of Rhodamine B reaches 82%,indicating that S-WO3 has the high stability.In addition,the analysis results show that sulfur element has a significant refinement effect on WO3 and sulfur doping can reduce band gap energy,which will lead the transitions of low energy electrons,growth of oxygen vacancies in WO3 and promotions on electron-hole separation,the photocatalytic efficiency is improved as a result.However,the degradation efficiency of Rhodamine B decreases when the sulfur doping ratio of S-WO3 exceeds 1.5%,for the reason that excessive oxygen vacancies form new recombination centers,which affect the process of electron hole separation negatively.