Abstract
Noble metals addition on nanostructured metal oxides is an attractive way to enhance gas sensing properties. Herein, hierarchical zinc oxide (ZnO) porous microspheres decorated with cubic gold particles (Au particles) were synthesized using a facile hydrothermal method. The as-prepared Au-decorated ZnO was then utilized as the sensing film of a gas sensor based on a quartz crystal microbalance (QCM). This fabricated sensor was applied to detect dibutyl phthalate (DBP), which is a widely used plasticizer, and its coating load was optimized. When tested at room temperature, the sensor exhibited a high sensitivity of 38.10 Hz/ppb to DBP in a low concentration range from 2 ppb to 30 ppb and the calculated theoretical detection limit is below 1 ppb. It maintains good repeatability as well as long-term stability. Compared with the undecorated ZnO based QCM, the Au-decorated one achieved a 1.62-time enhancement in sensitivity to DBP, and the selectivity was also improved. According to the experimental results, Au-functionalized ZnO porous microspheres displayed superior sensing performance towards DBP, indicating its potential use in monitoring plasticizers in the gaseous state. Moreover, Au decoration of porous metal oxide nanostructures is proved to be an effective approach for enhancing the gas sensing properties and the corresponding mechanism was investigated.
Highlights
Phthalates are multifunctional chemicals that have been widely used for decades and are widely found in the environment and in humans
Concentration over the range from 2 to 30 ppb and achieved a sensitivity of 23.51 Hz/ppb. Both sensors were highly sensitive to low concentrations of dibutyl phthalate (DBP), which was mainly attributed to the hierarchical nanostructure of the zinc oxide (ZnO) porous microspheres
Using a simple hydrothermal process followed by calcination, self-assembled hierarchical ZnO
Summary
Phthalates are multifunctional chemicals that have been widely used for decades and are widely found in the environment and in humans. When the application conditions change, corresponding modifications to the equation are needed [18] Based on this principle, nanogram-level mass changes can be determined by measuring the frequency shift (Δf) caused by the adsorption of target analytes onto the coated-QCM. ZnO is a typical n-type semiconductor which displays distinctive electrical, optical and electrochemical properties and has various applications such as transparent electrodes [29], solar cells [30], photocatalysts [31] and gas sensors [32,33] It is abundant in nature and low-cost, it retains high sensitivity, excellent stability, non-toxicity and suitability for doping, especially for gas sensing applications [34]. The obtained Au-decorated ZnO was used as the sensing film to fabricate a highly sensitive QCM for DBP detection at room temperature. The corresponding mechanisms responsible for the high sensitivity, selectivity and the enhancement caused by Au decoration were investigated
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