A novel method for metal oxide deposition on carbon aerogels with potential application in capacitive deionization of saline water

Carbon aerogels doped with manganese or iron oxides were prepared by the resorcinol-formaldehyde method as potential electrodes for the capacitive deionization of sodium chloride from saline water. The solution containing the metal precursors was mixed with the hydrogel before the supercritical drying step ensuring a highly homogeneous dispersion of the nanometric metal oxides as determined by X-ray diffraction and electron microscopy. XPS spectra revealed the increased contribution of hydroxyl and carboxylic groups after the activation process. Also, an enhanced metal oxidation at the outer particle surface was observed. Nitrogen isotherms have revealed a decrease of the pore volume in doped samples ascribed to the partial blocking of the pore structure by the embedded nanometric metal oxide particles. Capacitance values as large as 99 F/g and 91 F/g were respectively recorded for CAGDFeAct and CAGDMnAct by cyclic voltammetry. The large capacitance detected for the iron containing activated aerogel was confirmed by deionization experiments. An electrosorption capacity of 0.133 mmol/g was recorded for CAGDFeAct in a 0.025 M NaCl solution when 1.5 V were applied during the charge period. The study of the kinetic response of the electrodes showed a poor behavior for CAGDMnAct and was correlated to the partial blocking of pore structure exerted by the embedded nanometric metal oxide particles.The authors are indebted to the MICINN (Contract IPT-2011-1450-310000 (ADECAR) and CTM2011-23378) and Junta de Andalucía (Research group FQM-288) for the financial support. We also thank the fruitful collaboration of Isolux Ingeniería, S.A., Fundación Imdea Energia and Proingesa.Peer reviewe

A novel method for metal oxide deposition on carbon aerogels with potential application in capacitive deionization of saline water

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