摘要
二氧化铈(CeO_(2))材料因其独特的光、磁、电性能而备受关注,尤其在光催化降解环境污染物方面展现出了高效、无毒、低成本的显著优势。以硝酸铈和硝酸钐为原料,采用无模板一步水热法成功制备了具有类扫帚状形貌的钐离子掺杂二氧化铈(Sm-CeO_(2))光催化剂,详细研究了不同掺杂浓度对其光催化性能的影响,同时确定了最佳掺杂比为Ce/Sm摩尔比=1.00:0.15(0.15-SC)。紫外–可见吸收光谱表明Sm掺杂后的样品与未掺杂CeO_(2)相比带隙值(Eg)明显减小,最佳掺杂比时0.15-SC样品的Eg最小仅为2.88 e V。以环境污染物双酚A(BPA)为降解实验的模型,发现Sm掺杂后的CeO_(2)样品光催化降解效率均有一定程度的提升,且0.15-SC样品降解效率最高达99.83%,是未掺杂CeO_(2)(28.31%)的3.52倍。活性物质的猝灭实验可以判断出,羟基自由基(·OH)和空穴(h+)在0.15-SC样品光催化降解BPA过程中起到很大的作用。且在4次的性能循环性实验后,0.15-SC样品仍保持89.53%的降解率,表明其可循环利用性良好。本工作中钐离子掺杂后二氧化铈材料展现出较高的光催化净化环境污染物活性,充分证实了离子掺杂是一种有效提高光催化性能的方法,可为以后同类金属氧化物材料设计离子掺杂体系提供有效的思路。
Introduction Ceria (CeO_(2)) is an important rare earth metal oxide abundant in nature. Due to the easy conversion of the oxidationvalence between cerium ions, CeO_(2) has a high oxygen storage capacity. The band gap value of ceria is similar to that of othertraditional semiconductor photocatalyst of TiO2, so it has the potential to be a suitable and efficient photocatalyst. Specifically, iondoping can introduce new energy levels into the band structure of ceria, reduce its band gap width, and enable more visible light to beabsorbed, thereby ultimately improving the photocatalytic efficiency. Secondly, when other cations enter the CeO_(2) lattice, they formoxygen vacancies (oxygen defects) under structural deformation and charge compensation mechanisms. The oxygen vacancy formedin this process can act as an effective trapping point for photogenerated electrons, effectively reduce the recombination rate ofelectrons and holes, and significantly improve the photocatalytic efficiency of the material. In addition, ion doping can also changethe electronic structure of cerium oxide, making it have better conductivity and charge transport performance, which is conducive tothe separation and transport of photogenic carriers. Generally speaking, it is very difficult to introduce ions into the CeO_(2) lattice. Theauthor focuses on designing the synthesis system of CeO_(2) photocatalyst doped with Sm ions and systematically studying andsummarizing the reaction ratio relationship of raw materials, so as to elucidate the influence of ion doping on photocatalyticperformance from the perspective of photocatalytic mechanism.Methods Firstly, 5.88g C6H5Na3O7·2H2O and 60 ml deionized water were stirred magnetically together at room temperature for 30minutes. Then, 2.40 g urea was added and mixed for 30 minutes continually (solution 1). At the same time, 1.00 g Ce(NO3)3·6H2Oand different molar ratios of Sm(NO3)3·6H2O were dissolved in 20 ml deionized water and stirred for 30 minutes, respectively(solution 2). Next, solution 2 was added into solution 1 and continue to stir for 30 minutes until the solution shows a light-yellowcolor. Then, the mixed reaction liquid was transferred to a 100 ml hydrothermal reactor, and cooled naturally after the hydrothermalreaction at 120℃ for 36 hours. After used deionized water and ethanol to clean at least three times, and finally dried for 12 hours at70 ℃ and calcined at 500℃ for 4 hours to obtain the target product. At the same time, CeO_(2) product without addingSm(NO3)3·6H2O precursor were used as a comparison sample.Results and discussion The influence of different doping concentrations on the photocatalytic performance of ceria was studied indetail, and the optimal doping ratio of Ce and Sm was determined to be 1:0.15 (0.15-SC). SEM images indicated that Sm-dopedmaterial still maintained a broom-like morphology, but the surface smoothness, average diameter and length of the nanorods showedslight changes. From XRD analysis, all the samples exhibited sharp diffraction peaks, indicating high crystallinity, and no impuritypeaks are detected, meaning that the doping process does not affect the crystal purity of the final product. UV-vis absorption spectrumshows that the bandgap value (Eg) of these Sm-doped samples is significantly reduced compared to that of pure CeO_(2), and the Eg ofthe 0.15-SC sample is the smallest at only 2.88 eV. The factors that lead to the reduction of the band gap can be attributed to twopoints: First, the nanoscale CeO_(2) composed grains can induce the quantum limiting effect, which leads to the spectral redshift;Second, the decrease of particle size will increase the Ce3+ content at the edge of CeO_(2). With the decrease of Ce3+ content, the UV-visspectra will also show a redshift phenomenon.Compared with other Sm-CeO_(2) samples, pure phase CeO_(2) showed the strongest characteristic peak strength and the lowest peakstrength when the doping ratio was 1:0.15, indicating that Sm-CeO_(2) samples had the best effect on promoting the separation ofphotogenerated holes and electron pairs and photocatalytic performance at this ratio. The environmental pollutant bisphenol A (BPA)was used as a photocatalytic degradation model, and it was found that the efficiency of all the Sm-doped CeO_(2) samples was improved,and the degradation efficiency of the 0.15-SC sample was the highest, reaching 99.83%, which was 3.52-times superior than that ofthe pure CeO_(2) (28.31%). The capture experiment of the active substances can be judged that both hydroxyl radicals (•OH) and holes(h+) played very important roles in the photocatalytic degradation of BPA on the 0.15-SC sample. And after four performance cyclingexperiments, the degradation rate of the 0.15-SC sample was still maintained 89.53%, indicating that it has good recyclability.Conclusions In summary, the Sm-doped ceria material exhibits high photocatalytic purification activity for environmentalpollutants, fully proving that ion’s doping can act as an effective method to efficiently improve photocatalytic performance, and canfurther provide effective ideas for designing ion-doping systems for similar metal oxide materials in the future.
作者
王一帆
钱文轩
徐冬
侯建华
杨慧
WANG Yifan;QIAN Wenxuan;XU Dong;HOU Jianhua;YANG Hui(College of Environmental Science and Engineering,Yangzhou University,Yangzhou 225127,Jiangsu,China)
出处
《硅酸盐学报》
北大核心
2025年第5期1057-1065,共9页
Journal of The Chinese Ceramic Society
基金
国家自然科学基金青年项目(22406161)
扬州市“绿杨金凤”优秀博士项目(137013435)
扬州大学“高端人才支持计划”。
关键词
二氧化铈
离子掺杂
光催化降解
双酚A
ceria
ion’s doping
photocatalytic degradation
bisphenol A
作者简介
第一作者:王一帆(2005-),女,本科;通信作者:杨慧(1994-),女,博士,讲师。
