Primary voltaic sources including nanofiber Schottky barrier arrays and methods of forming same

A method for producing a primary voltaic source, comprising:

• reacting at least one carbon oxide and a reducing agent in the presence of a substrate comprising a catalyst to form a solid carbon product over the substrate;
• disposing a material over at least a portion of the solid carbon product to form a Schottky barrier array comprising a semiconductor component and a metallic coating over the semiconductor component, the semiconductor component comprising at least one selected from the group consisting of a semiconductor carbon nanotube and a carbon nanofiber, the semiconductor component and the metallic coating joined at a metal-semiconductor junction, the Schottky barrier array defining a plurality of voids therein;
• and
• disposing a radioactive source comprising at least one radioactive element configured to emit radioactive particles proximate to the Schottky barrier array such that the radioactive source occupies at least a portion of the plurality of voids and such that at least a portion of radioactive particles leaving the radioactive source impinge on the Schottky barrier array to produce a flow of electron across the metal-semiconductor junction.