Abstract
Pristine and electrochemically Pd-modified ZnO nanorods (ZnO NRs) were proposed as active sensing layers in chemiresistive gas sensors for hydrocarbon (HC) gas detection (e.g., CH4, C3H8, C4H10). The presence of Pd nanoparticles (NPs) on the surface of ZnO NRs, obtained after the thermal treatment at 550 °C, was revealed by morphological and surface chemical analyses, using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. The effect of the Pd catalyst on the performance of the ZnO-based gas sensor was evaluated by comparing the sensing results with those of pristine ZnO NRs, at an operating temperature of 300 °C and for various HC gas concentrations in the range of 30–1000 ppm. The Pd-modified ZnO NRs showed a higher selectivity and sensitivity compared to pristine ZnO NRs. The mean sensitivity of Pd-modified ZnO NRs towards the analyzed HCs gases increased with the length of the hydrocarbon chain of the target gas molecule. Finally, the evaluation of the selectivity revealed that the presence or the absence of metal nanoparticles on ZnO NRs improves the selectivity in the detection of specific HCs gaseous molecules.
Highlights
Hydrocarbons (HCs) are molecules consisting of carbon and hydrogen atoms, and the gaseous species can be present in the atmosphere depending on their volatility or vapor pressure
As volatile molecules in the atmosphere, they are classified as volatile organic compounds (VOCs)
We propose a one-step strategy based on sacrificial anode electrolysis (SAE) to synthesize stabilized Pd NPs [44], directly deposited on the surface of sol–gel pre-synthesized ZnO nanostructures
Summary
Hydrocarbons (HCs) are molecules consisting of carbon and hydrogen atoms, and the gaseous species can be present in the atmosphere depending on their volatility or vapor pressure. The prepared hybrid Pd@ZnO nanostructures are proposed as active layer in chemiresistive gas sensors for the detection of pollutant HCs. The effect of the Pd catalyst on the performance of ZnO-based gas sensors was investigated by the comparison of the gas sensing results of pristine and Pd-modified ZnO NRs, at an operating temperature of 300 °C, towards methane (CH4), propane (C3H8) and butane (C4H10) at a wide range of gas concentrations (30–1000 ppm).
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