Synergistic MnHCF/Biomass-Derived Carbon Asymmetric Electrodes for High-Performance Capacitive Deionization

With increasing water scarcity, capacitive deionization (CDI) has emerged as a promising desalination technology due to its cost-effectiveness and environmental friendliness. However, electrode materials significantly influence the CDI performance. To address the poor cycling stability of manganese-based Prussian blue analogs (MnHCF), this study synthesized biomass-derived porous carbon (FSB850) from the bark of Firmiana simplex (commonly known as Chinese parasol tree, synonymous with Firmiana platanifolia) via KOH activation for use as an anode, paired with MnHCF as a cathode. Electrochemical and desalination tests revealed a synergistic effect between the two materials, achieving a high salt adsorption capacity (SAC) of 25.80 mg·g^-1 in 500 mg·L^-1 NaCl solution and 83.72% cycling stability over 100 cycles. The results demonstrate the potential of biomass-derived carbon for enhancing CDI performance and provide insights into sustainable electrode design. Moreover, we observed that the asymmetric device demonstrated superior SAC under a constant current of 0.053 mA compared to that at a constant voltage of 1.4 V, indicating a potential pathway toward achieving lower energy consumption in capacitive deionization operations.