Composite waste-corn-stalk-derived carbon aerogel and sea-urchins γ-MnO2 structure for high-performance pseudo-capacitance deionization

This study reported the synthesis, characterization, and electrochemical performance of sea-urchins gamma-MnO2 structure and its composites with carbon aerogel (CA) derived from Waste-corn-stalk for capacitive deionization (CDI) application. Scanning electron microscopy revealed distinct sea-urchin morphologies where gamma-MnO2 exhibited a fibrous, porous structure, and its integration with CA resulted in composites with varied porosity and particle size distributions; X-ray diffraction analysis confirmed the crystalline nature of gamma-MnO2. It indicated a successful composite formation with CA, which was observed to enhance the electrochemical performance via the synergistic charge storage effect. Cyclic voltammetry and charge-discharge tests showed that the composites, particularly CA/gamma-MnO2-30, had superior electrochemical performance compared to gamma-MnO2 pristine, with improved capacitance and rate capabilities. CDI performance assessments demonstrated that the composite CA/gamma-MnO2-30 significantly outperformed in salt adsorption capacity of 32.7 mg/g, highlighting the potential of these materials for efficient water desalination. The electrosorption kinetic process of CA/gamma-MnO2 composites is suitable for the pseudo-second-order (PSO) model by combining the double-layer adsorption and the pseudo-capacitance process.