Design of highly sensitive and selective Au@NiO yolk–shell nanoreactors for gas sensor applications

Abstract

Au@NiO yolk-shell nanoparticles (NPs) were synthesized by simple solution route and applied for efficient gas sensor towards H₂S gas. Carbon encapsulated Au (Au@C core-shell) NPs were synthesized by glucose-assisted hydrothermal method, whereas Au@NiO yolk-shell NPs were synthesized by precipitation method using Au@C core-shell NPs as a template. Sub-micrometer Au@NiO yolk-shell NPs were formed having 50-70 nm Au NPs at the periphery of NiO shell (10-20 nm), which was composed of 6-12 nm primary NiO particles. Au@NiO yolk-shell NPs showed higher response for H2S compared to other interfering gases (ethanol, p-xylene, NH₃, CO and H₂). The maximum response was 108.92 for 5 ppm of H₂S gas at 300 °C, which was approximately 19 times higher than that for the interfering gases. The response of Au@NiO yolk-shell NPs to H₂S was approximately 4 times higher than that of bare NiO hollow nanospheres. Improved performance of Au@NiO yolk-shell NPs was attributed to hollow spaces that allowed the accessibility of Au NPs to gas molecules. It was suggested that adsorption of H₂S on Au NPs resulted in the formation of sulfide layer, which possibly lowered its work function, and therefore tuned the electron transfer from Au to NiO rather NiO to Au, which leaded to increase in resistance and therefore response.

Preparation of Pd nanoparticle-decorated hollow SnO 2 nanofibers and their enhanced formaldehyde sensing properties

“…Among the latest studies, metallic catalysts such as Ag [21], Au [20], Pd [22], and Pt [23] nanoparticles loaded onto the surfaces of the oxide supports serve as sensitizers or promoters, dramatically improving the sensing response, recovery time, and sensitivity. For example, Tong Zhang etc [24] prepared Ring-like PdO-decorated NiO by hydrothermal method.…”

“…In recent years, many researchers have made tremendous effort towards the development on the semiconductor gas sensors in various ways [19,20]. Among the latest studies, metallic catalysts such as Ag [21], Au [20], Pd [22], and Pt [23] nanoparticles loaded onto the surfaces of the oxide supports serve as sensitizers or promoters, dramatically improving the sensing response, recovery time, and sensitivity.…”

Highly stabilized and rapid sensing acetone sensor based on Au nanoparticle-decorated flower-like ZnO microstructures

“…On the other hand, noble metals, well known as active catalysts, have been confirmed to possess the promoting effects on many semiconductor gas sensors [27,28]. Au nanoparticles have attracted considerable attention.…”

Tuning SnO 2 architectures with unitary or composite microstructure for the application of gas sensors

“…There are many approaches we can choose to rational design and construct the morphology and surface state. Various techniques have been developed for the controlled synthesis of functional materials with special morphology, such as hydrothermal method [8,9], electrochemical method [10], template method [11] and magnetron sputtering method [12]. Materials with special morphology can also be achieved by tuning the reaction condition, i.e., the concentration of precursors [8,13], reaction temperature [9] and reaction time [14].…”