Fiber-Optic Microfiber: Tracking Activity Enhancement and Suppression of Heterogeneous Photocatalysts

Abstract

Obtaining detailed insight into the photocatalytic performance of heterogeneous photocatalytic materials, is important for evaluating material properties as well as guiding material design. However, capture of the detailed matter changes on a photocatalyst surface in real time, and in situ during photocatalysis remains challenging. This work reports a promising optical microfiber sensor integrating a photocatalytic reaction monolayer on an optical microfiber surface to monitor reaction kinetics using Cu₂O-based heterogeneous photocatalysts, as an example. The evanescent field of microfiber is used to track the photocatalytic process in real time, through the interaction with the catalytic layer, by monitoring the surface refractive index changes caused by adsorption and degradation. Since the catalytic layer is less than 1 µm thick, the typical high-power light source can be replaced by low-power light irradiation. This method successfully reveals that relative to the pristine Cu₂O microspheres, the photocatalytic activity is enhanced by the incorporation of Ti₃C₂Tx MXene into Cu₂O, whereas incorporation of CdS into Cu₂O suppresses the activity. Compared with the existing methods used for photocatalysis evaluation, this optical microfiber can be directly employed in real matrices to track local photocatalytic performance. It can also provide details about the different adsorption/degradation kinetics of photocatalysts. It is suitable for most photocatalytic processes and is not limited to pollutants with characteristic UV–visible absorption spectra. This study provides important inspiration for the future development of in situ, real-time reaction assessment.

Funding

National Natural Science Foundation of China(U1701268); Natural Science Foundation of Guangdong Province(2019A1515011278); Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2019BT02X105); Special Funds for the Cultivation of Guangdong College Students' Scientific and Technological Innovation(pdjh2020a0061); Undergraduate Innovation and Entrepreneurship Program(202010559050)