Photoinduced superhydrophilicity and high photocatalytic activity of ZnO–reduced graphene oxide nanocomposite films for self-cleaning applications

A series of ZnO–reduced graphene oxide (ZnO–rGO) nanocomposite films were developed on glass substrate by a sol–gel technique. The deposited films were highly transparent and showed enhanced photocatalytic activity with increasing rGO content. Significantly, the films showed surface hydrophilicity and photoinduced superhydrophilicity that enhanced with the increase of rGO/ZnO ratio. The enhancement of photocatalytic activity of ZnO–rGO films with increasing rGO/ZnO ratio is attributed to the enhancement of their efficient charge separation owing to electrons injection from the conduction band of ZnO to graphene, the decrease of average particle size, and the increase of superhydrophilicity. The promising characteristics (inexpensive, transparent, photoinduced superhydrophilic, and highly photocatalytically active) make the ZnO–rGO films have the potential use in self-cleaning and various indoor applications.