▎ 摘　　要

NOVELTY - Near-infrared light gain gas sensing film comprises gas-sensitive sensing material layer and an up-conversion nano particle layer which are arranged in a laminated manner. The material of the up-conversion nanoparticle layer is polyelectrolyte-modified up-conversion nanoparticles. The material of the gas-sensitive sensing material layer is a gas-sensitive sensing material with photocatalytic activity. The exciting light with photocatalytic activity is one of ultraviolet light and visible light. USE - Near-infrared light gain gas sensing film used in gas-sensitive electrode for sensor (all claimed). ADVANTAGE - The near-infrared photocatalytic activated gas sensor has large penetrating ability and harmless to the body, and reduces the detection limit and significantly improves the sensitivity. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for follwoing: (1) a method for preparing a near-infrared light gain gas sensing thin film, which involves preparing polyelectrolyte-modified upconversion nanoparticles, spin-coating polyelectrolyte-modified upconversion nanoparticles on a substrate to prepare an upconversion nanoparticle layer and arranging a gas-sensitive sensing material layer on the up-conversion nano particle layer. (2) A gas-sensitive electrode, which comprises a base electrode, and the near-infrared light gain gas sensor film is provided on a surface of the base electrode.