Electric field-induced amplification of graphene oxide's visible light photocatalytic activity†

A static external electric field (EEF) is for the first time successfully applied to enhance the photocatalytic activity of graphene oxide (GO) photocatalysts functionalized by either zinc porphyrins or perylene diimide. The applied 4 kV EEF increases the reaction rate of the hybrid-assisted photodestruction of a model organic pollutant, 1,5-dihydroxynaphthalene (DHN), in water by 2.2–2.3 times in a contactless transparent static electric cell. A control material presenting zinc porphyrins on the non-polarizable MoS₂ nanosheets does not change its activity in EEF. Ultrafast time-resolved photoluminescence spectroscopy, photoluminescent hydroxyl radical probing, and the GC-MS analysis of the supernatant solutions are used to confirm no effect of EEF on photochemical properties of the porphyrins as well as on the pathway of photodestruction of DHN. The DFT calculations show that the dielectric properties and polarizability of GO play a key role in the EEF-induced enhancement of photocatalysis due to the decrease in electron energy facilitating its transfer from GO into water or substrate. Our finding may provide a basis for an affordable alternative for conventional electrophotocatalysis schemes to advance this field towards more effective green-chemistry technologies and to encourage the rational design of new carbon-based photocatalysts, which can be applied for EEF-facilitated photocatalysis.