基于超疏水表面的氧化亚铜光催化稳定性研究

Cuprous oxide, as a green and environment-friendly semiconductor that can be generated by visible light, is a promising material in catalytic industry. However, the application of the catalyst is limited extremely by its poor photo-stability. The project presents a strategy to improve the photo-stability of cuprous oxide in photo-catalytic reactions. The strategy involves the introduction of a superhydrophobic substrate to support cuprous oxide, in which large amount of oxygen is trapped. Since oxygen serves as an electron trapper in the photo-catalytic reaction, the photo-electrons could be captured immediately as soon as the electron-hole pairs are generated. Thus the possibility for the cuprous ions to combine with photo-electrons is reduced and the photo-stability of the catalyst is improved. Furthermore, by capturing the photo-electrons efficiently, the electron trapper could also prevent the holes from being recombined by the electrons and thus improves the catalytic efficiency. The project will be performed by the electrochemical deposition of cuprous oxide on a superhydrophobic surface and the photo-corrosion of the catalyst will be investigated in detail. Since the procedure of electro-chemical deposition is highly-developed and the equipments required for the material characterization and catalysis measurement are all available in the lab, the project is highly performable. Besides, the research experiences of the proposer in the field of microstructure preparation and wettability will also benefits the performance of the project. It could be expected that, the problem of the photo-stability of cuprous oxide would be resolved by the proposal and an effective new way to improve the catalytic efficiency would be developed.

氧化亚铜是一种绿色环保的可见光催化剂，但由于光稳定性较差使得其应用大为受限。本项目拟从超浸润界面调控的角度出发来解决氧化亚铜光稳定性问题。具体思路是：由于氧气是光催化过程中非常有效的电子捕获剂，而超疏水界面可富集大量氧气，因此，可通过借助超疏水表面增大富氧量的方式来提高光催化体系中电子捕获剂浓度，进而降低由于电子过多聚集而导致的一价铜被还原的几率，最终达到抑制光腐蚀、提高光稳定性的目的。此外，氧气含量的增加还有利于提高电子-空穴的分离效率，进而提高光催化效率。项目拟采用电化学沉积工艺在超疏水表面上沉积氧化亚铜，并对其光腐蚀行为展开研究，所用制备工艺成熟、所需检测表征易于实现，可保证研究路线的可行性；同时，项目申请人对氧化物半导体材料制备及浸润性研究非常熟悉，具有良好的前期工作积累。可以预期，项目提出的方案将成为提高氧化亚铜催化剂光稳定性的有效途径。

项目通过构建基于超疏水基底的三相光催化模型，研究了该模型在提高催化剂光稳定性、光催化效率、入射光利用率、耐受性等方面的作用。通过以最具代表性的光催化剂氧化钛为例进行的研究结果表明，基于超疏水基底的三相光催化模型可有效提高光催化剂的光稳定性、避免光腐蚀；同时可将光降解率提高至两相光催化体系的9.1倍，并可将降解速率随入射光强增强而线性增大的范围从~10 mW·cm-2提升至~70 mW·cm-2，大大提高了入射光强的选择范围和利用率；不仅如此，三相光催化体系还表现出优异的稳定性和耐受性，经20次循环使用后，仍保持初始光催化性能的95%；而相应的两相光催化体系则在第1次使用之后光催化降解率就衰减为原来的50%。在此基础上，我们进一步构筑石墨烯掺杂氧化钛的三相光催化体系，并对其光催化性能进行研究。结果表明，对掺杂后的三相光催化体系，其降解率约为相应两相体系的30倍，进一步证实了三相光催化体系对于提高光催化降解率的重要作用；反应动力学研究表明，经石墨烯掺杂后，氧化钛三相光催化体系的降解速率常数可提高至原来的2倍。这为进一步提高三相光催化体系的光催化效率提供了便捷途径。总的研究结果表明，我们提出的通过构建三相光催化模型来提高光稳定性的思路是可行的；由于三相界面的存在，该模型不仅可以有效避免光腐蚀，同时还可大大提高光降解效率及稳定性，且其光催化效率还可通过掺杂等技术得到进一步提高。这一研究结果不仅有助于突破传统技术瓶颈提高催化剂光稳定性，同时也为我们开发新型高效光催化模式提供了新思路。