(271a) Synthesis of Graphene from Mango Biomass Via PECVD

In the year 2004, a wonder material only one atom thick was discovered. The materials is an allotrope of carbon known as Graphene. The carbon atoms are arranged in hexagonal shapes with sp² hybridization state. Graphene has found numerous applications in catalysis, Li-ion batteries, water purification, gas separation, super capacitors, quantum computing, building materials, composites and several others. Graphene has been synthesized by several methods such as mechanical exfoliation, hydrothermal treatment and chemical vapor deposition.

In traditional CVD process, the reaction time is in the order hours, if not days. Also, the use of non-conventional sources of carbon like biomass, plastic waste, etc takes even more time with growth temperature of > 900 ℃. Recently, with the advancements in plasma technology, the traditional CVD process has been modified to Plasma Enhanced Chemical Vapor Deposition. A carbon source is usually required to form graphene, traditionally methane and copper is used as a substrate.

Materials and Methods:

Mango peels are a waste in the food industry but rich in carbon. Biomass derived from mango peel has been used as the carbon source in this study. The biomass is placed on a copper substrate in a Quartz tube used as a the PECVD reactor. The plasma gas used was 10% Hydrogen and 90% Argon. The PECVD reactor operates at a temperature of 750 ℃. The plasma chamber was under vacuum and a power of 300 W was used. A 15 minute annealing time was used for all synthesis.

Results:

The synthesis was carried out for 5-60 minutes growth period to monitor the effect on quality and elucidate a possible mechanism fo the synthesis. Monolayer graphene was obtained at synthesis time of 60 minutes with least defects. At lower synthesis time either the defects were too high or multilayer graphene was obtained. Plasma treatment was essential for synthesis of graphene. With only thermal annealing, graphene was not obtained.