Green synthesis of crystalline silicon nanoparticles (SiNPs) via magnesiothermic reduction of mesoporous silica extracted from sugarcane bagasse ash (SCBA)

Abstract

In this study, crystalline silicon nanoparticles (SiNPs) were successfully produced utilising a low-temperature magnesiothermic reduction method of mesoporous silica nanoparticles (SiO2NPs). Silicon nanoparticles (SiNPs) have gained attention in recent years due to their range of applications and specific properties. However, producing high-purity SiNPs necessitates high-energy production, such as carbothermic reduction at >2000 °C, in addition to the significant pollutants and CO2 emissions generated throughout the process. Thus, there has been an increase in research on extracting SiNPs from various agricultural wastes as a cost-effective source. This study investigates the extraction of SiO2NPs using sol-gel synthesis from sugarcane bagasse ash (SCBA) and resulted in a purity of 94.8% utilising XRF. After magnesiothermic reduction of SiO2NPs at 650 °C, XRD and Raman confirmed the resulting crystalline SiNPs. Furthermore, SEM and TEM were used to investigate the morphology along with BET to determine specific surface area, pore volume, and pore diameter, which resulted in 57.85 m2/g, 0.18 cm3/g, and 12.4 nm, respectively, for the produced SiNPs. Additionally, this study includes the use of a green-sustainable synthesis method to decrease energy usage and attempts to replace toxic counterparts with reagents such as the use of L-cysteine hydrochloride monohydrate and citric acid, while obtaining high-purity SiNPs. SiNPs have a variety of possible applications in new advancements, including energy production like solar photovoltaic cells and energy storage devices, which contribute towards the UN's sustainable development goals (SDG), particularly SDG 7 (Affordable and clean energy) and SDG 13 (Climate Action), as this study exhibits sustainability and increases the potential to reduce biomass waste production.