基于杉木模板的Zn2+掺杂TiO2的光催化性能研究

  目的  针对木材加工行业带来的加工剩余物浪费问题，本研究以杉木为模板，通过浸渍–煅烧的方法，制备具有木材分级多孔结构的Zn2+掺杂TiO₂复合光催化剂，利用木材加工剩余物的高值化利用的方式提高光催化材料的性能。  方法  以亚甲基蓝溶液为降解对象，探讨了不同的Zn2+掺杂对木材模板TiO₂的光催化活性的影响，并结合XRD、SEM、XPS、BET、TEM和UV-vis等表征分析探讨模板二氧化钛的光催化降解机制。  结果  以杉木为模板的Zn-TiO₂具有良好的孔隙结构，其晶型为锐钛矿型和少量的金红石型的混晶结构，平均晶粒尺寸为22.0 nm。掺杂的Zn2+取代了Ti4+的晶格的位置，使TiO₂吸收波长在可见光区发生红移。在紫外光照射条件下，杉木模板1.0%Zn-TiO₂对亚甲基蓝的降解效率最高，达到了99.31%，相比无模板TiO₂提升了27%，同时其禁带宽度相比于无模板TiO₂从3.08 eV减小至2.41 eV。在循环降解亚甲基蓝的实验中，5次降解效率均达到90%以上。  结论  采用木材模板法制备的Zn-TiO₂光催化降解有机污染物性能优异，具有良好的稳定性。木材独特的孔隙结构有利于光的吸收和传质，较高的比表面积为光催化提供了更多的活性位点。Zn2+与被替代的Ti4+由于半径和价态差异使晶格内产生晶格缺陷，抑制了光生电子–空穴的复合，增加了载流子的运输，从而提高光催化性能。将木材剩余物的加工与多孔无机材料领域相结合，对木材加工剩余物的功能化转变具有潜在的应用前景。 

Photocatalytic activity of Zn2+ doped TiO2 based on Chinese fir template

Objective]In view of the waste of processing residues in wood processing industry,Zn²⁺doped TiO₂composite photocatalyst with hierarchical porous structure of wood was prepared by impregnation calcination method.Chinese fir was used as template to improve the photocatalytic performance.Method]Taking methylene blue solution as the target degradation object,the effects of different concentrations of Zn²⁺doping on the photocatalytic activity of wood template TiO₂were discussed.The photocatalytic degradation mechanism of wood template TiO₂was analyzed by XRD,SEM,XPS,BET,TEM and UV-Vis.Result]The Zn²⁺doped wood template TiO₂presents good pore structure that hierarches from wood.It is a mixed crystal structure of anatase and rutile TiO₂.The average grain size was 22.0 nm.The Zn²⁺replaced the lattice position of Ti4+,which made the absorption wavelength of TiO₂presenting red shift in the visible region.Under UV irradiation,the degradation efficiency of methylene blue solution with 1.0%Zn-TiO₂reached 99.31%.Compared with the TiO₂without template,its degradation efficiency increased by 27%.Compared with the templated TiO₂,the band gap decreased from 3.08 to 2.41 ev.The degradation efficiency can be retained 90%after five repeated experiments.Conclusion]Zn²⁺doped TiO₂prepared with wood template shows excellent photocatalytic degradation performance and stability.The unique pore structure is conducive to light absorption and mass transfer,and the higher specific surface area provides more active sites for photocatalysis.Due to the difference of radius and valence state between Zn²⁺and Ti4+,lattice defects will appear in the lattice,which can inhibit the recombination of photogenerated electrons and holes,increase the carrier transport and improve the photocatalytic performance.Thus,wood residues utilization with functional inorganic materials can present a promising prospect in industrial applicaion.