▎ 摘　　要

NOVELTY - Air-cleaning device comprises: an air inlet for intaking air from the outside; an ozone generating unit in which at least one ozone generator of corona discharge ozone generator or cold plasma ozone generator is located; an ozone decomposition unit for removing ozone generated in ozone generating unit, in which support and an ozone decomposition catalyst structure including nano manganese oxide are located; and an air outlet for outflowing internal air to outside, where nano manganese oxide (3) is located on at least a portion of inside (2) and surface of the support, the nano manganese oxide includes at least one of alpha -manganese oxide, beta -manganese oxide, gamma -manganese oxide, delta -manganese oxide, or amorphous manganese oxide, and nano manganese oxide has shape comprising e.g. nanorod shape, a nanofiber shape, and a nano sea-urchin shape. The nano manganese oxide further comprises e.g. metal oxide, silicon oxide, and graphene oxide. The support is ceramic material, and/or metal material. USE - The device is useful for reducing harmful gases including ethylene and harmful microorganisms, where the harmful gas comprises an organic-inorganic harmful gas including ethylene, ammonia, and/or acetaldehyde and the harmful microorganisms comprises fungi, Escherichia coli, Pseudomonas aeruginosa, and/or Staphylococcus (all claimed). ADVANTAGE - The device: enables the inflow and outflow of air in one direction; effectively reduces or removes harmful gas including ethylene, harmful microorganism, and ozone, without exchanging filters; and maintains the freshness of fruits and vegetables in a closed space e.g. a reservoir. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) reducing harmful gases including ethylene and harmful microorganisms; and (2) air-cleaning system. DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram showing an ozone decomposition catalyst structure. Support (1) Inside of support (2) Nano manganese oxide (3)