NH3冷等离子体制备高稳定性Au-NHx-TiO2-y可见光催化剂及反应性能研究

Au/TiO2 is one of the most promising visible-light photocatalysts, due to its high visible-light response and good catalytic activity. However, Au/TiO2 is of poor stability, and there are obvious deactivation phenomena during storage and reaction, which hinders its popularization in practical applications. In order to solve this problem, in this study, NHx-TiO2-y support was prepared by NH3 cold plasma. Then Au was anchored to NHx groups of NHx-TiO2-y by plasma or impregnation. Thus, the Au-NHx-TiO2-y visible-light catalyst with high stability was obtained. Based on the results of optical emission spectra, experimental characterization and DFT calculation, the mechanism of TiO2 modified by NH3 cold plasma was revealed. Finally, Au-NHx-TiO2-y was used for visible-light catalytic oxidation of formaldehyde, and the intrinsic relationship between the structure and stability of Au-NHx-TiO2-y was ascertained by an in-situ catalyst characterization technique. The results of this project can provide important theoretical basis and practical reference for the preparation and application of high stability Au/TiO2 visible-light catalysts.

Au/TiO2催化剂具有可见光响应程度高和催化活性好的特点，是最有望商业化的可见光催化剂之一。然而，Au/TiO2的稳定性较差，在储存和反应过程中都存在着明显的失活现象，这阻碍了其在实际应用中的推广。针对这一问题，本研究拟采用NH3冷等离子体制备NHx-TiO2-y载体，进而通过等离子体法和浸渍法将Au锚定于NHx基团，获得具有高稳定性的Au-NHx-TiO2-y可见光催化剂。结合发射光谱原位诊断技术、催化剂表征和密度泛函理论计算，揭示NH3冷等离子体改性TiO2的机制。最后，将Au-NHx-TiO2-y用于可见光催化氧化甲醛反应，通过原位催化剂表征技术，探明催化剂结构与稳定性之间的内在联系。本项目的研究结果可以为高稳定性Au/TiO2可见光催化剂的制备与应用提供重要的理论依据和现实参考。

研究和制备一种高活性和高稳定性的纳米Au可见光催化剂，可极大地推动和拓展光催化技术的实际应用。纳米Au颗粒由于其高表面能，在储存和反应过程中易团聚失活，如何抑制Au颗粒的迁移是提高催化剂稳定性的关键。本研究采用NH3冷等离子体制备NHx-TiO2-y载体，通过浸渍氯金酸将Au锚定于NHx基团，制备了结构为Au-NHx-TiO2-y的可见光催化剂，进而通过CO氧化反应验证了Au-NHx-TiO2-y的高稳定性。以此为基础，系统研究了冷等离子体处理纳米Au催化剂的活化机制，具体研究结果包括：（1）通过板-板介质阻挡放电，采用NH3冷等离子体掺杂改性TiO2，得到以间隙掺杂为主的NHx-TiO2-y。N的掺入拓展了TiO2的可见光吸收，提高了其可见光活性；（2）以卟啉铁为Fe和N源，通过NH3冷等离子体一步实现了氧化石墨烯的还原和Fe，N的共掺杂，制备的催化剂保留了石墨烯的片层结构，表面富含高活性位点的Fe-N-C和吡啶氮；（3）采用不同放电气体活化Au/TiO2，O2等离子体活化的催化剂上纳米Au颗粒粒径较小，且具有良好的抗烧结能力，其表面含有大量氧物种，有利于CO氧化反应的进行；（4）以HAuCl4∙4H2O为Au源，O2/Ar为放电气体，制备得到结构为Au-NHx-TiO2-y的可见光催化剂，通过连续实验以及不同放置时长对照，确定了该催化剂具有良好的稳定性。本项目完成了预期研究内容，所获得的结果可为高稳定性Au/TiO2可见光催化剂的制备与应用提供重要的理论依据和现实参考。