Photoluminescence amplification of cerium incorporated graphene oxide nanoparticles by photoinduced reduction: A mechanistic study highlighting structural orderness

This work demonstrates a strategy to overcome the limitation of weakly luminescent graphene oxide (GO) based materials by using a simple one pot synthesis of enormously luminescent cerium ion incorporated graphene oxide nanoparticles (GO-Ce NPs). Apart from more than 100 fold amplification of photoluminescence intensity compared to graphene oxide, the origin of such enhancement of GO-Ce NPs is investigated by exploring binding interaction between cerium ions and GO NPs and the structural orderness of the GO NPs in presence of cerium. XPS confirms the existence of two oxidation states of cerium in GO-Ce NPs. Experimental observations enable us to conclude a mechanism involving photoinduced reduction of non emissive Ce (IV) to form luminescent Ce (III) accompanied with energy pumping of cerium by photoexcited GO NPs in the structurally ordered GO-Ce nanoparticles. Again, the interaction between the cerium ions and the oxygen containing functional groups of GO leads to decoupling of the functional groups and there by weakens the intensity of luminescence originated from disordered induced defect states which results a non radiative chanel to generate trivalent cerium via single electron transfer from the orbitals of the functional groups to the vacant 4f orbitals of tetravalent cerium.

Automated summary

This study demonstrates a strategy to enhance the luminescence of graphene oxide materials by synthesizing cerium ion incorporated graphene oxide nanoparticles. The origin of luminescence enhancement in GO-Ce NPs is attributed to the binding interaction between cerium ions and GO NPs as well as the structural orderness in the presence of cerium. Experimental observations suggest a mechanism involving photoinduced reduction of non emissive Ce(IV) to form luminescent Ce(III) accompanied with energy pumping of cerium by photoexcited GO NPs.