A method of forming metal oxide nanotubes on a surface of a structure, the method comprising: centrally positioning a structure comprising a metal relative to at least three cathodes , wherein the at least three cathodes are positioned radially around the centrally positioned structure, wherein the metal is at least 0.1 weight percent of the structure and the structure is in contact with a central anode ; submerging at least a portion of the structure and the at least three cathodes in an electrolyte solution; and applying a constant voltage between the anode and the at least three cathodes for a period of time sufficient to form metal oxide nanotubes on the surface of the structure, wherein the anode and the at least three cathodes are positioned in a coating device comprising: a first plate comprising a central anode receiving opening and at least three cathode receiving openings positioned radially around the central anode receiving opening ; a second plate positioned in opposition to the first plate and comprising at least three cathode receiving openings ; a plurality of supports separating the first and second plates ; a centrally positioned receiving region between the first and second plates ; the at least three cathodes extending through the at least three cathode receiving openings of the first plate and into the at least three cathode receiving openings of the second plate ; and the anode extending through the central anode receiving opening and contacting the structure and positioning the structure in the centrally positioned receiving region , wherein the metal oxide nanotubes comprise an average length of from 200 nm to 600 μm and an average diameter of from 1 nm to 1000 nm. centrally positioning a structure comprising a metal relative to at least three cathodes , wherein the at least three cathodes are positioned radially around the centrally positioned structure, wherein the metal is at least 0.1 weight percent of the structure and the structure is in contact with a central anode ; submerging at least a portion of the structure and the at least three cathodes in an electrolyte solution; and applying a constant voltage between the anode and the at least three cathodes for a period of time sufficient to form metal oxide nanotubes on the surface of the structure, wherein the anode and the at least three cathodes are positioned in a coating device comprising: a first plate comprising a central anode receiving opening and at least three cathode receiving openings positioned radially around the central anode receiving opening ; a second plate positioned in opposition to the first plate and comprising at least three cathode receiving openings ; a plurality of supports separating the first and second plates ; a first plate comprising a central anode receiving opening and at least three cathode receiving openings positioned radially around the central anode receiving opening ; a second plate positioned in opposition to the first plate and comprising at least three cathode receiving openings ; a plurality of supports separating the first and second plates ; a centrally positioned receiving region between the first and second plates ; the at least three cathodes extending through the at least three cathode receiving openings of the first plate and into the at least three cathode receiving openings of the second plate ; and the anode extending through the central anode receiving opening and contacting the structure and positioning the structure in the centrally positioned receiving region , wherein the metal oxide nanotubes comprise an average length of from 200 nm to 600 μm and an average diameter of from 1 nm to 1000 nm. <EOS>