The disclosed technology generally relates to energy storage devices, and more particularly to energy storage devices comprising frustules. According to an aspect, a supercapacitor comprises a pair of electrodes and an electrolyte, wherein at least one of the electrodes comprises a plurality of frustules having formed thereon a surface active material. The surface active material can include nanostructures. The surface active material can include one or more of a zinc oxide, a manganese oxide and a carbon nanotube.