doi:10.1038/nindia.2016.36 Published online 14 March 2016
By using extracts of mango leaf and potato, researchers have converted graphene oxide into reduced graphene oxide sheets that show excellent thermal stability and electrical conductivity1. This method offers an eco-friendly way to synthesize reduced graphene oxide, which is potentially useful for fabricating electronic devices.
Current techniques for producing reduced graphene oxide sheets require harmful synthetic chemicals that contaminate graphene sheets and may induce irreversible aggregation.
To overcome this problem, the researchers separately added extracts of mango leaf and potato to graphene oxide solutions. On heating, the graphene oxide solutions changed from brownish yellow to dark black, indicating the formation of sheets consisting of a few layers of reduced graphene oxide.
Both extracts contain polyphenols, such as caffeic acid, chlorogenic acid, gallic acid, protocatechuic acid, salicylic acid and vanillic acid, which converted graphene oxide into reduced graphene oxide.
The plant polyphenols increased the negative charge density of the graphene sheets by partially removing oxygen-containing functional groups from the graphene oxide. The negative charges repulsed each other, preventing aggregation and facilitating dispersion of the graphene sheets in water.
The plant polyphenols imparted stability to the graphene sheets so that they could withstand high temperatures. In addition, the graphene sheets exhibited a higher electrical conductivity than graphene oxide, suggesting that they could be used in devices.
1. Sadhukhan, S. et al. Studies on synthesis of reduced graphene oxide (RGO) via green route and its electrical property. Mater. Res. Bull. 79, 41–51 (2016)