▎ 摘　　要

NOVELTY - NGQD/ferrous oxide/graphene foam composite film comprises a graphene foam substrate which is loaded with iron oxide nanospheres, where the iron oxide nanospheres are embedded with aminated graphene quantum point. USE - The NGQD/ferrous oxide/graphene foam composite film is used as a sensitive layer in butyraldehyde gas sensors. ADVANTAGE - The NGQD/ferrous oxide/graphene foam composite film has low working temperature, high sensitivity to gas, high selectivity to butyraldehyde, excelent repeatability, and excellent stability. The method is cost-effective and simple, and enables large-scale production. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a method for preparing NGQD/ferrous oxide/graphene foam composite film comprising (a) preparing graphene foam substrate, (b) adding aminated graphene quantum dots to the iron precursor solution, and stirring to prepare a sol solution, (c) immersing the graphene foam substrate in the sol solution for pulling up and coating, and taking it out to dry, (d) placing the dried sample in an airtight container and treating it by post-heating steaming method, and (e) placing the sample processed in step (d) under inert gas for heat treatment to obtain NGQD/ferrous oxide/graphene foam composite film; and (2) an application of the NGQD/ferrous oxide/graphene foam composite film as a sensitive layer in a butyraldehyde gas sensor, where the graphene foam substrate is welded on the sensor device.