Encapsuled nanoreactors (Au@SnO2): a new sensing material for chemical sensors

TLDR

The study proposes a growth model for Au@SnO2 yolk–shell nanospheres. Au@SnO2 yolk–shell nanospheres were synthesized via hydrothermal shell‑by‑shell deposition on Au@SiO2 templates, yielding 110‑nm spheres with 15‑nm shells, and their gas‑sensing behavior was compared to hollow SnO2. Au@SnO2 nanospheres exhibit superior gas‑sensing performance, achieving a 210 °C operating temperature, 5 ppm detection limit, 0.3 s response, and improved selectivity due to Au catalysis and surface electron depletion.

Abstract

New Au@SnO2 yolk–shell nanospheres have been successfully synthesized by using Au@SiO2 nanospheres as sacrificial templates. This process is environmentally friendly and is based on hydrothermal shell-by-shell deposition of polycrystalline SnO2 on spheriform Au@SiO2 nanotemplates. Au nanoparticles can be impregnated into the SnO2 nanospheres and the nanospheres show outer diameters of 110 nm and thicknesses of 15 nm. The possible growth model of the nanospheres is proposed. The gas sensing properties of the Au@SnO2 yolk–shell nanospheres were researched and compared with that of the hollow SnO2 nanospheres. The former shows lower operating temperature (210 °C), lower detection limit (5 ppm), faster response (0.3 s) and better selectivity. These improved sensing properties were attributed to the catalytic effect of Au, and enhanced electron depletion at the surface of the Au@SnO2 yolk–shell nanospheres.