Mn-Containing N-Doped Monolithic Carbon Aerogels with Enhanced Macroporosity as Electrodes for Capacitive Deionization

We propose the use of siliceous diatomite as an antishrinkage additive for the synthesis of monolithic carbon aerogel electrodes with enhanced electrochemical response for capacitive deionization of NaCl solutions. Hybrid N- and Mn-doped carbon aerogels with improved electrical conductivity and wettability in the aqueous electrolyte are prepared by introducing modifications in the synthesis (carbon black and/or diatomite loading before the polymerization sol–gel polycondensation of the monomers, followed by manganese infiltration). The textural and morphological characterizations of the materials reveal that the presence of the additives does not impede the cross-linking of the monomers to form branched clusters and colloidal aggregates leading to a highly porous structure. Furthermore, the aerogel materials display an open macroporous network inherited by the diatomite, even after its lixiviation. As a result, the monolithic carbon aerogel electrodes present good electrochemical performance in terms of low polarization resistance, high capacitance, and fast electroadsorption.
The authors are indebted to the MINECO (Contract IPT-2011-1450-310000 (ADECAR) and FEDER cofunding, and CTM2014-56770-R) for the financial support. We also thank the fruitful collaboration of Isolux Ingeniería, S.A., Fundación Imdea Energía and Proingesa.University of Cordoba thanks to SCAI and IUIQFN for technical support and Junta de Andalucía (FQM-288) for financial support.