Graphitized cornstarch as a high-performance biomass-derived electrode for sustainable capacitive deionization

Abstract

The use of graphitized cornstarch, a biomass-derived carbon material, was explored as a high-performance electrode for capacitive deionization (CDI). Cornstarch was thermally treated at 1000 °C to produce a graphitic carbon structure with a high surface area (332.28 m² g⁻¹, BET), excellent electrical conductivity, and residual functional groups. The electrochemical performance of the graphitized cornstarch electrode was evaluated using cyclic voltammetry (CV), chronoamperometry, and electrosorption capacity measurements in NaCl solutions. The results demonstrate a specific capacitance of 1088.7 F g⁻¹ at 1 mV s⁻¹, significantly higher than that of conventional activated carbon (73.5 F g⁻¹). The CDI cell assembled with graphitized cornstarch electrodes achieved an electrosorption capacity of 11.3 mg g⁻¹ at 1.2 V in 0.03 M NaCl, compared to only 0.3 mg g⁻¹ for activated carbon. Furthermore, the graphitized cornstarch electrode exhibited excellent stability and reversibility, with a consistent performance over multiple adsorption–desorption cycles. The presence of residual functional groups, as confirmed by FTIR analysis, contributed to pseudocapacitive behavior, enhancing the overall ion adsorption capacity. These findings highlight the potential of biomass-based electrodes, such as graphitized cornstarch, to address the challenges of water scarcity through sustainable and efficient CDI technology. This study provides valuable insights into the design and optimization of biomass-derived carbon materials for next-generation desalination systems.