Preparation of Graphene Using Rice Husk via Pyrolysis Technique for CO<sub>2</sub> Adsorption

Graphene is the only carbon allotrope in which every carbon atom is densely connected to its neighbours by an electronic cloud, raising various quantum physics concerns. In recent years, many researchers have focused their efforts on developing more efficient methods for synthesizing graphene. However, only few methods can simultaneously synthesize mass-produced, cost-effective, and high-quality graphene. In this study, we are emphasizing the use of rice husk (RH) as the raw material to prepare graphene by using two-step pyrolysis. Zinc chloride (ZnCl 2 ) is an example of an activating agent that is used to improve the efficiency of the synthesis of graphene from rice husk. After conducting pre-treatment of rice husk, the first stage of pyrolysis was conducted by varying the ratio of ZnCl 2 to the RH (1:1, 2:1, 3:1) at a carbonization temperature of 500 °C for 1 hour, followed by second-stage pyrolysis under 900 °C for 90 minutes and post-treatment. The findings of the characterizations, which included yield analysis, scanning electron microscopy (SEM) and Raman spectroscopy, Brunauer-Emmett-Teller (BET), and CO 2 adsorption analysis, revealed the impacts of the ZnCl 2 as activating agent, on the yield and graphitic structure of graphene and the potential application of graphene as a CO 2 adsorbent. Raman spectroscopy confirmed the graphitic properties of graphene synthesized in all samples with RH1:1 produced the best quality of graphene due to its low I D /I G intensity ratio (0.8913) and the highest I 2D /I G intensity at 0.24. In addition, RH1:1 exhibited the highest surface area, whereby the highest total pore and micropore volume is contributing to the highest CO 2 adsorption capacity of 8.73 mmol/g. This proves that the activating agent ratio has significant effects on the graphene quality produced from rice husk as well as the adsorption performance.