Organic and inorganic gels, and gel-derivatives such as aerogels and xerogels, find numerous applications in areas such as batteries, fuel cells, photoelectrochemical solar cells, photocatalytic devices, supercapacitors, control-release drug delivery systems, separation techniques, and others.  Modern microscopic and electrochemical techniques offer the possibility of understanding structural properties of these systems down to almost atomic level.  Most of the applications involve solid-liquid interfaces that occupy a significant fraction of the volume of these materials.