Synthesis of carbon dots (C-dots) from rice pit coal (Oryza sativa.l) by microwave method.

This study aims to determine how to synthesize and determine the physical, optical, and chemical characteristics of C-dots made from rice husk charcoal. The research stages include sample preparation, synthesis of C-dots using the microwave method, preparation of C-dots solution and characterization. Synthesis of C-dots was carried out by mixing ricehusk charcoal precursor with a NaOH 1M. The resulting C-dots glow green when exposed with UV light at range of wavelengths 453-525 nm, and brown when exposed with sunlight. The results showed that variations in the volume of NaOH solvent and microwave time resulted indifferent characteristics of C-dots. PSA test result showed the average particle size of C-dots 219.9 nm, 271.3 nm, and 305.9 nm. XRD test results show 3 types of crystalline phases possessed by C-dots made from rice husk charcoal, namelygraphite-2H (002) at 2θ = 26.37°, graphite-3R (003) at 2θ = 26.56°, and diamondsyn (111) at 2θ = 43.88°. Based on the tauc plot method, we known that the C-dots with the volume variation of the solvent NaOH 5; 7; 10 mL has a band gap of 4.7129 eV; 4.5074 eV; 3.4279 eV and the C-dots with microwave time variations 5; 7; 10 minutes has a band gap of 4.7129 eV; 5.2152 eV; 5,2990 eV. The results of the FTIR analysis showed that C-dots made from rice husk charcoal have functional groups C=C in the core area and C-O and O-H in the surface area. Based on these data, it can be stated that thesynthesized C-dots have physical characteristics is a chocolate liquid with a particle size of 219.9 nm; 271.3 nm; and 305.9 nm and have semi-crystalline properties. The C-dots crystal phase consists of 2-H graphite, 3-R graphite, and diamond. [ABSTRACT FROM AUTHOR]