Abstract
Novel Ni-doped wurtzite ZnS nanospheres decorated with Au nanoparticles (Au NPs–ZnS NSs) have been successfully fabricated using a simple method involving vacuum evaporation followed by an annealing process. This transition metal-doped gas sensor had high responsivity, extremely fast response and recovery time, and excellent selectivity to formaldehyde at room temperature. The response and recovery time are only 29 s and 2 s, respectively. Since ZnS is transformed into ZnO at a high temperature, superior room temperature-sensing performance can improve the stability and service life of the sensor. The improvement in sensing performance could be attributed to the reduced charge-transfer distance resulting from the creation of a local charge reservoir layer, and the catalytic and spillover effect of Au nanoparticles. The rough and porous spherical structure can also facilitate the detection and diffusion of gases. The as-prepared Au NPs–ZnS NSs are considered to be an extremely promising candidate material for gas sensors, and are expected to have other potential applications in the future.
Highlights
Formaldehyde is a gas that is harmful to human health
A gold thin film was optionally deposited on the surfaces of the as-synthesized Ni-doped Zinc sulfide (ZnS) nanospheres by using a DC sputtering technique
In the samples with Au decoration after annealing, some sharp diffraction peaks corresponding to (100), (002), (110), (112), (202), and (203) planes are well matched with the standard hexagonal wurtzite phase of ZnS in JCPDS file No 75-1547
Summary
Formaldehyde is a gas that is harmful to human health. The World Health Organization (WHO)states that exposure to formaldehyde for 30 min in an environment with a concentration greater than 0.08 ppm will harm human health [1]. Formaldehyde is a gas that is harmful to human health. States that exposure to formaldehyde for 30 min in an environment with a concentration greater than 0.08 ppm will harm human health [1]. Formaldehyde is widely found in building materials, such as chemical adhesives. It has become one of the main pollutant gases in the indoor environment. A previous study has shown that the formaldehyde concentration in the exhaled gas of lung cancer patients reaches 83 ppb, while it is 48 ppb for healthy counterparts [2]. It is highly desirable to monitor the environmental formaldehyde concentration in real time by using high-precision and high-sensitivity portable gas sensors
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