Synthesis of porous small-sized ZnO nanoparticles and their gas-sensing performance

Mao, Y.Z.; Ma, S.Y.; Li, W.Q.; Luo, J.; Cheng, Liang; Gengzang, D.J.; Xu, Xingtang

doi:10.1016/j.matlet.2015.05.028

“…The preparation of ZnO templates is not the limitation of the CVD synthesis in terms of its scalability. ZnO with adjustable particle sizes and nanostructures can be easily synthesized by using a variety of well‐established methods [40–43] …”

Section: Resultsmentioning

confidence: 99%

Chemical Vapor Deposition for Atomically Dispersed and Nitrogen Coordinated Single Metal Site Catalysts

Liu

¹

,

Wang

²

,

Yang

³

et al. 2020

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Atomically dispersed and nitrogen coordinated single metal sites (M-N-C,M= Fe,Co, Ni, Mn) are the popular platinum group-metal (PGM)-free catalysts for many electrochemical reactions.Traditional wet-chemistry catalyst synthesis often requires complex procedures with unsatisfied reproducibility and scalability.H ere,w er eport af acile chemical vapor deposition (CVD) strategy to synthesize the promising M-N-C catalysts.T he deposition of gaseous 2-methylimidazole onto M-doped ZnO substrates,f ollowed by an in situ thermal activation, effectively generated single metal sites well dispersed into porous carbon. In particular,a no ptimal CVDderived Fe-N-C catalyst exclusively contains atomically dispersed FeN 4 sites with increased Fe loading relative to other catalysts from wet-chemistry synthesis.T he catalyst exhibited outstanding oxygen-reduction activity in acidic electrolytes, which was further studied in proton-exchange membrane fuel cells with encouraging performance.

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“…The preparation of ZnO templates is not the limitation of the CVD synthesis in terms of its scalability.ZnO with adjustable particle sizes and nanostructures can be easily synthesized by using av ariety of well-established methods. [40][41][42][43] Then, 2-MeIm and the as-prepared Fe-ZnO nanosheets were placed in two separate alumina combustion boats in af urnace with two temperature zones,r espectively.T he temperatures for the up and downstream zones are heated to 280 and 350 8 8C, respectively.A sar esult, the evaporated gaseous 2-MeIm flows with the argon gas and subsequently deposits onto Fe-ZnO nanosheets.T he gas-solid reaction leads to the formation of Fe-Zn(MeIm) 2 intermediate according to the proposed reaction mechanism: [44] 2MeIm(g) + ZnO(s)!Zn(MeIm) 2 (s) + H 2 O(g). TheCVD growth temperature of the downstream is crucial in controlling the crystalline structure of the intermediates.…”

Section: Synthesis Principles and Catalyst Propertiesmentioning

confidence: 99%

Chemical Vapor Deposition for Atomically Dispersed and Nitrogen Coordinated Single Metal Site Catalysts

Liu

¹

,

Wang

²

,

Yang

³

et al. 2020

View full text Add to dashboard Cite

Atomically dispersed and nitrogen coordinated single metal sites (M-N-C,M= Fe,Co, Ni, Mn) are the popular platinum group-metal (PGM)-free catalysts for many electrochemical reactions.Traditional wet-chemistry catalyst synthesis often requires complex procedures with unsatisfied reproducibility and scalability.H ere,w er eport af acile chemical vapor deposition (CVD) strategy to synthesize the promising M-N-C catalysts.T he deposition of gaseous 2-methylimidazole onto M-doped ZnO substrates,f ollowed by an in situ thermal activation, effectively generated single metal sites well dispersed into porous carbon. In particular,a no ptimal CVDderived Fe-N-C catalyst exclusively contains atomically dispersed FeN 4 sites with increased Fe loading relative to other catalysts from wet-chemistry synthesis.T he catalyst exhibited outstanding oxygen-reduction activity in acidic electrolytes, which was further studied in proton-exchange membrane fuel cells with encouraging performance.

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“…Among these, ZnO, a wide band gap (~3.34-3.37 eV) [29] semiconductor, is widely used for applications such as varistors [30], memristors [31], solar cells [32], piezoelectric devices [33], and light emitting diodes [34]. Low resistivity, nontoxicity, large exciton binding energy, different nanostructured geometries, along with high surface-to-volume ratios make ZnO nanoparticles an excellent choice for optoelectronic and gas/vapor sensing applications [35,36]. ZnO is considered a "chemoresistive" sensing material, wherein the presence/absence of adsorbed oxygen species on its surface alters the amount of free carriers available to participate in charge transport [11,26], which can be used to sense, e.g., oxygen [27], hydrogen [20], ethanol [37], NO x [38], acetone [39], NH 3 [40], and CO [41].…”

Section: Introductionmentioning

confidence: 99%

Thin Film Gas Sensors Based on Planetary Ball-Milled Zinc Oxide Nanoinks: Effect of Milling Parameters on Sensing Performance

Sapkota

¹

,

Duan

²

,

Kumar

³

et al. 2021

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Planetary ball-milled zinc oxide (ZnO) nanoparticle suspensions (nanoinks) were used to produce thin film chemiresistive gas sensors that operate at room temperature. By varying milling or grinding parameters (speed, time, and solvent) different thin film gas sensors with tunable particle sizes and porosity were fabricated and tested with dry air/oxygen against hydrogen, argon, and methane target species, in addition to relative humidity, under ambient light conditions. Grinding speeds of up to 1000 rpm produced particle sizes and RMS thin film roughness below 100 nm, as measured by atomic force and scanning electron microscopy. Raman spectroscopy, photoluminescence, and X-ray analysis confirmed the purity and structure of the resulting ZnO nanoparticles. Gas sensor response at room temperature was found to peak for nanoinks milled at 400 rpm and for 30 min in ethylene glycol and deionized water, which could be correlated to an increased film porosity and enhanced variation in electron concentration resulting from adsorption/desorption of oxygen ions on the surfaces of ZnO nanoparticles. Sensor response and dynamic behavior was found to improve as the temperature was increased, peaking between 100 and 150 °C. This work demonstrates the use of low-cost PBM nanoinks as the active materials for solution-processed thin film gas/humidity sensors for use in environmental, medical, food packaging, laboratory, and industrial applications.

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Synthesis of porous small-sized ZnO nanoparticles and their gas-sensing performance

Cited by 14 publications

References 13 publications

Chemical Vapor Deposition for Atomically Dispersed and Nitrogen Coordinated Single Metal Site Catalysts

Chemical Vapor Deposition for Atomically Dispersed and Nitrogen Coordinated Single Metal Site Catalysts

Chemical Vapor Deposition for Atomically Dispersed and Nitrogen Coordinated Single Metal Site Catalysts

Thin Film Gas Sensors Based on Planetary Ball-Milled Zinc Oxide Nanoinks: Effect of Milling Parameters on Sensing Performance

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