Toward a New Understanding of Graphene Oxide Photolysis: The Role of Photoreduction in Degradation Pathway.

Graphene oxide (GO) is developed in various applications owing to its fascinating physicochemical properties. However, the weak photostability always leads to inevitable photolysis of GO during the use, storage, and application. Indirect photolysis has a significant impact on the structure of GO via causing fragmentation and degradation, while the pathway can be divided into two stages. In the early stage, photoreduction is the dominant reaction to generate porous reduction GO (PrGO). Then HO breaks PrGO into fragments, and eventually, the fragmented GO is converted into CO by OH radicals. The generation of porous structures in early photoreduction is a crucial premise for the subsequent photodegradation, while GO flakes without porous structure cannot be broken by HO and OH. In this work, a deep insight into the indirect photolysis pathway and the committed step is provided, which may bring some advanced ideas for enhancing GO stability in practical application.