Aminated Graphene Oxide Impregnated with Photocatalytic Polyoxometalate for Efficient Adsorption of Dye Pollutants and Its Facile and Complete Photoregeneration

Contamination of industrial sewage by organic dye pollutants is one of the most common challenges to the daily life. De-contamination can be achieved by adsorption and photodegradation of the pollutants. However, the former technique is generally limited by the poor loading capacity of the adsorbent and/ or the difficulty in its regeneration for reuse, while the latter often suffers from sluggish reaction kinetics and thus requires long reaction time and powerful light source to be successful. Herein, a solution to these challenges by creating nanocomposites featuring porous diamine-functionalized graphene oxide (FGO) impregnated with photocatalytically active polyoxometalates (POMs) is presented. Cross-linking of GO via diamination not only generates porous structures with positively charged interior that attracts and stabilizes the anionic POM guests, but also modulates the GO bandgap. The introduction of POMs improves loading capacity of FGO for cationic dyes and promotes effective separation of electron-hole pair by trapping and transferring photogenerated electron. Thus, the two components act in synergy to result in much improved adsorption of certain common organic dyes as well as enhanced oxidative degradation by both the GO host and the POMs that lead to complete regeneration of the adsorbents without compromising their performance in multiple rounds of reuse.