▎ 摘　　要

Three-dimension (3D) hierarchical SnO2@rGO nanocomposites (SRGNC) of layered SnO2 nanorods arrays anchored on reduced graphene oxide were fabricated by a hydrothermal approach. The layered SnO2 nanomds arrays were employed in-situ growth mechanism via a straightforward nanocrystal-seeds-directing on reduced graphene oxide. The 3D hierarchical structure of the SRGNC demonstrated a unique brush-like SnO2 arrayed nanorods with a diameter of approximately 7 nm and a length of several hundred nanometers. Applied as a gas sensing material, the SnO2@2.5 %rGO nanocomposite demonstrated ultra-high performance for formaldehyde gas that the gas response toward 50 ppm formaldehyde is up to 5437 at the lower optimal operating temperature of 50 degrees C. Not only that, the sensor based on SnO2@2.5 %rGO nanocomposite exhibited good selectivity, reproducibility, long term stability, and ultralow-limit gas detection (as low as 500 ppb). The perfect sensing performances could be attributed to the electronic coupling effect, the enlarged specific surface with abundant active sites and the special array structure of SnO2 nanomds.