▎ 摘　　要

NOVELTY - A composite material comprises functional graphene and oxygen-containing vacancy-rich zinc oxide. The functionalized graphene is reduced graphene modified with an organic matter. The oxygen-containing vacancy-rich zinc oxide has an oxygen vacancy content of 40% or more. USE - Composite material is used for preparing light activated gas sensor for detecting trace formaldehyde detection (all claimed). ADVANTAGE - The composite material has good response value and recovery, ultra-low detection limit, good cycle stability and selectivity, can realize long-term stable detection at room temperature, and has important effect for environmental protection and safety. The raw material used by the composite material is simple and easy to obtain, low in cost, and environmentally-friendly. The composite material can be prepared by a simple method on a large scale. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following: (1) preparation of the composite, which involves adding a reducing agent to a mixture of aqueous solution containing organic matter and graphene oxide dispersion, heating and reacting to obtain functional graphene, and dispersing the oxygen-containing vacancy-rich zinc oxide in the functional graphene; (2) formaldehyde sensor; (3) preparation of the formaldehyde sensor; and (4) formaldehyde detection method.