Synthesis, characterization and energy gap of silica quantum dots from rice husk

This study aimed to reveal roles of KOH and HCl in a synthesis process of Silica Quantum Dots (Si-QDs) from environmentally friendly rice husk waste, the morphological characteristics, size and crystal structure of particles as well as the energy gap of Si-QDs. The results showed that High Energy Milling (HEM) caused electron excitation, delocalized bonding, nanocrack and fracture. KOH played a role in producing Si-QDs sizes around 0.386–2.5 nm. The most efficient hexagonal crystal structure absorbed the peak wavelength of about 250–400 nm and glowed a purplish-blue color. The Si-QDs produced Si and O content was 97 % with 3 % of K, Fe, and Ca impurities. The obtained energy gap 1.59–2.36 eV and HOMO-LUMO 127 99.5 kcal/mol. The smaller size of Si QDs, the higher energy gap which was associated with the quantum confinement effect.