The present invention has a first substrate having a high thermal conduction portion which has a thermal conductivity higher than that of other regions in a plane direction, a thermoelectric conversion layer which is formed on the first substrate, consists of an organic material, and has a thermoelectric conversion material having a positive Seebeck coefficient, a second substrate which is formed on the thermoelectric conversion layer and has a high thermal conduction portion having a thermal conductivity higher than that of other regions in the plane direction and in which the high thermal conduction portion does not completely overlap the high thermal conduction portion of the first substrate in the plane direction, and a pair of electrodes which are connected to the thermoelectric conversion layer and consist of a metal material having a negative Seebeck coefficient. As a result, there are provided a thermoelectric conversion element and a thermoelectric conversion module which can generate heat with excellent efficiency by using a thermoelectric conversion material consisting of an organic material.

A thermally and electrically conductive structure comprises a carbon nanotube (110) having an outer surface (111) and a carbon coating (120) covering at least a portion of the outer surface of the carbon nanotube. The carbon coating may be applied to the carbon nanotube by providing a nitrile-containing polymer, coating the carbon nanotube with the nitrile-containing polymer, and pyrolyzing the nitrile-containing polymer in order to form the carbon coating on the carbon nanotube. The carbon nanotube may further be coated with a low contact resistance layer (130) exterior to the carbon coating and a metal layer (140) exterior to the low contact resistance layer.

A carbon nanotube aggregate includes a plurality of carbon nanotubes, a metal compound added to inside and/or outside of each of the carbon nanotubes, and an oxide film that is made of an oxide of the metal compound, and covers an outer periphery of the plurality of carbon nanotubes to define an outer surface of the carbon nanotube aggregate. Since the metal compound is shielded from the atmosphere by the oxide film, separation of the metal compound and reaction of the metal compound with oxygen or water in the atmosphere are suppressed, increasing heat resistance of the carbon nanotube aggregate.

Provided is an oxidized carbon nanotube assembly having excellent dispersibility in a polar solvent. The oxidized carbon nanotube assembly includes oxidized single-walled carbon nanotubes, has a ratio of the number of oxidized single-walled carbon nanotubes relative to the total number of oxidized carbon nanotubes in the oxidized carbon nanotube assembly of 51% or more, and has a heat of immersion per unit area in water of not less than 1,500 mJ/m.sup.2 and not more than 10,000 mJ/m.sup.2.

A multifunctional end cap catalyst is provided, comprising a multi-wall carbon nanotube with a multi-metal catalyst at the end cap. The catalyst contributes preferentially to growing a multi-wall carbon nanotube through a methane pyrolysis process at a lower temperature, and then infuses the nanotube into a host material, such as concrete, asphalt, polymer, or steel, improving functional parameters including thermal conductivity, electrical conductivity, wettability, flexural strength, tensile strength, or interfacial bonding strength. The catalyst can also increase the host material's decrease phonon scattering or interfacial resistance, and lower the final defect density of the multi-wall carbon nanotube. The multifunctional end cap catalyst can be composed of various metals, including copper, nickel, and manganese, and can achieve specific functional states, such as oxidized or functionalized metal states, without increasing the final defect density.