Improvement of Photocatalytic Power and Dimensional Stability via In Situ Synthesis of Carbon Dot on Cellulose Nanofiber

Photocatalytic reaction is a fascinating technology for sustainable development, as it can effectively and simply degrade pollutants. Titanium oxide is a well-known material of powerful photocatalytic performance. However, large energy consumption and air pollutant are inevitable for the titanium oxide sintering process. To find an alternative photocatalytic material under green process is an arising issue. Carbon dot is one of the eco-friendly carbon nanomaterials as it can be prepared in mild conditions, from various organic materials. Owing to its unique optical properties, carbon dot can be applied for photocatalyst. However, carbon dot itself showed low photocatalytic performance without metal nanoparticles. Carbon dot needs to be fixed on the metal support to improve the photocatalytic performance and the dimensional stability. It is critical to find a suitable bulk matrix to replace metal nanoparticles. When carbon dot is embedded in a polymer matrix, the surface functional groups of the carbon dot are buried in the matrix, and the photocatalytic effect would be significantly suppressed.<br/>In this study, we solved those two problems by attaching carbon dot at surface of cellulose nanofiber. Via simple and mild <i>in-situ</i> synthesis, carbon dot was chemically linked to the cellulose nanofiber and the functional groups of the carbon dot were exposed to the composite surface. Beyond the role as a matrix, cellulose nanofiber changed the electron recombination pathway and synergetically helped to improve the photocatalytic performance of the carbon dot. The composite degraded 98% of methylene blue molecules within 25 min. The fibrous structure of cellulose nanofiber makes ease of converting the composite morphology into aerogel. Without sacrificing its photocatalytic performance, the aerogel had good re-usability.