In-situ graphene oxide reduction via inkjet printing using natural reducing inks

The development of eco-friendly alkali lignin-assisted water-based stable graphene oxide (GO) ink presents an innovative approach with the potential to revolutionize the manufacturing of printed and flexible electronics through scalable inkjet printing. However, GO lacks conductivity, necessitating an additional reduction step to restore its electrical properties. Traditional reduction methods using toxic agents or high temperatures are not suitable for large-scale manufacturing due to environmental hazards. In-situ reduction techniques using natural substances offer a promising, cost-effective, and continuous solution for precise reduction of GO-printed patterns via inkjet printing. However, limited research has been conducted on natural-based inkjet printable reducing inks. In this work, in-situ inkjet printable natural reducing inks were produced and printed on top of GO-printed patterns to carry out the reduction process. The reduced printed patterns were investigated for structural, functional groups, morphology, and electrical resistance. The ascorbic acid reduced sample showed an increase in the I (D)/I (G) ratio from 1.058 to 1.15, and the interlayer distance decreased from 0.395 to 0.385 nm. The atomic force microscope surface analysis showed a significant increase in the mean roughness by three times for the ascorbic acid-reduced sample, indicating success in the reduction process. The ascorbic acid reduced patterns also showed an electrical conductivity of 1250 S m(-1) compared to 0.43 S m(-1) for unreduced GO printed patterns, indicating restoration of the sp(2) hybridised conductive networks.