| 摘要 |
PROBLEM TO BE SOLVED: To stably control an electron emission characteristic to improve efficiency by disposing a catalyst for decomposing water molecules contained in a vacuum part by light irradition, inside a device with a plurality of electron emission elements arranged. SOLUTION: A catalyst 112 for decomposing water with light is disposed in a surface conductive electron emission element composed of an electron source substrate 102 with a plurality of electron emission elements arranged, and an emission display substrate 101 with a phosphor 111. The catalyst 112 is preferably formed of a semiconductor catalyst carrying noble metal such as Pt on semiconductor powder such as TiO2 or CdS, or an oxide catalyst of transition metal such as NiO2, with a band gap having a larger value than the decomposition energy 1.23 eV of water. In order to accelerate reaction with light, it is preferable to dispose the catalyst 112 between the phosphor 111 and a black body 110 adjacent to the phosphor 111, or between the phosphor 111 and a metal back 113. Light of 500 nm or less is irradiated to the catalyst 112 to decompose water contained in a vacuum part, into oxygen and hydrogen.
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