A visual validation of the combined effect of pH and dilution on the porosity of carbon xerogels

The hypothesis about the formation of the porous structure of carbon xerogels when the pH and the dilution ratio of the precursor solution are simultaneously modified has been validated by means of scanning electron microscope analysis. The morphology of the carbon xerogels showed that the size and number of the clusters produced during the sol–gel reaction is not only influenced by the pH but also by the dilution ratio. As with a decrease in the pH value, an increase in the dilution ratio caused the formation of a small number of large clusters, leading to materials with large pores. However, depending on the values selected the effect of the pH and dilution ratio was enhanced or diminished by the effect of the other. Hence, an appropriate adjustment of these two variables allowed microporous, micro-mesoporous and micro-macroporous materials to be obtained with pore volumes that could not be achieved by modifying the pH or the dilution ratio separately.Financial support from the Ministerio de Economía y Competitividad of Spain MINECO (under Projects MAT2011-23733 and IPT-2012-0689-420000, (BES-2012-052676)) is greatly acknowledged. NRR is also grateful to MINECO for her predoctoral research grant.Peer reviewe