Bioderived Reduced Graphene Oxide from <i>Sterculia foetida</i> for Efficient Adsorptive Dye Removal and Electrochemical Characterization

Pervasive use of dyes in industries leads to contamination of water, which results in potential hazards to humans and the environment. In contrast to photodegradation method, adsorption-based dye removal is considered an efficient and cost-effective way with no secondary environmental hazardous by-product. In the present study, environmentally benign method was used for preparation of reduced graphene oxide (rGO), an efficient adsorbent. A low-cost and facile method starting from biochar of Sterculia foetida was used for obtaining rGO nanosheet. Morphological, vibrational and structural transformation suggest possible transformation of biochar to rGO. Adsorption capacity studies of rGO using methylene blue (MB) reveal that rGO is a promising adsorbent. 0.2 mg mL^-1 of rGO marks 94.04% dye removal of 2.5 ppm MB solution. It follows pseudo-second-order kinetics depicting both physisorption and chemisorption. Further studies were also performed to investigate the electrochemical behavior of rGO for supercapacitor applications. The double-layer capacitance obtained for rGO (2.08 × 10^-4 mF cm^-2) is ∼1.5 times higher as compared to that of bare glassy carbon electrode (GCE: 1.37 × 10^-4 mF cm^-2). The higher adsorption of ions is the main reason for the enhanced double-layer capacitance of rGO.