this invention provides non - spherical nanoparticle compositions that are the reaction product of a source of a group 12 , 13 , 14 , or 15 metal or metalloid ; a source of a group 15 or 16 element ; and a source of a quaternary ammonium compound or phosphonium compound ; wherein nanoparticle tetrapods comprise 75 - 100 number percent of the nanoparticle products .