Non-planar nanoscale p–p heterojunctions formation in Zn Cu1O  nanocrystals by mixed phases for enhanced sensors

Lupan, Oleg; Creţu, Vasilii; Postica, Vasile; Polonskyi, Oleksandr; Ababii, Nicolai; Schütt, Fabian; Kaidas, Victor; Faupel, Franz; Adelung, Rainer

doi:10.1016/j.snb.2016.02.089

Cited by 75 publications

(106 citation statements)

References 74 publications

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“…4 Due to specific surface conduction mechanism of p-type semiconducting oxides, the gas sensing mechanism is dominated by copper oxide. [12][13][14] It can be observed from Figure 5c, that the highest gas response of ZnO-T-ZnAl2O4…”

Section: Gas Sensing Properties Of 3-d Hybrid Ceramic Networkmentioning

confidence: 92%

“…[3][4][12][13][14] As above mentioned, before the integration of ZnO-T-MexOy and ZnO-TZnxMe1-xOy (Me = Fe, Cu, Al) hybrid networks into the sensor structure, the as-produced samples were subjected to thermal annealing in an electrical furnace at 1150 ºC for 5 h in air.…”

Section: Methodsmentioning

confidence: 99%

“…The gas sensing measurement procedures were realized following the same procedure described in previous reported works. 3,[12][13][14] Concentration of all tested gases (H2, ethanol vapour (EtOH), CO and CH4) was 100 ppm, as in previous works. 3,15 The relative humidity (RH) value during the measurements was set at normal ambient conditions of 30% RH, and was continuously measured by a standard hygrometer inside the test chamber.…”

Section: Methodsmentioning

confidence: 99%

“…The fabricated sensors were tested at a higher RH value of 70%, using a bubbling system as reported previously. 12,50 The obtained results are presented in Figure 6 and Table S3. A decrease in gas response for all sensors was observed with an increase of the RH value to 70%.…”

Section: Gas Sensing Properties Of 3-d Hybrid Ceramic Networkmentioning

confidence: 98%

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Hybridization of Zinc Oxide Tetrapods for Selective Gas Sensing Applications

Lupan

Postica

Gröttrup

et al. 2017

ACS Appl. Mater. Interfaces

135

111

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In this work, the exceptionally improved sensing capability of highly porous 3-D hybrid ceramic networks with respect to reducing gases is demonstrated for the first time. The 3-D hybrid ceramic networks are based on metal oxides Me= Fe, Cu, Al) doped and alloyed zinc oxide tetrapods (ZnO-T) forming numerous heterojunctions. A change in morphology of the samples and formation of different complex microstructures is achieved by mixing the metallic (Fe, Cu, Al) microparticles with ZnO tetrapods grown by flame transport synthesis (FTS) approach with different weight ratios (ZnO:Me, e.g., 20:1) and followed by subsequent thermal annealing them in air. The gas sensing studies reveal the possibility to control and change/tune the selectivity of the materials, depending on the elemental content ratio and the type of the added metal oxide in 3-D ZnO-T hybrid networks.While pristine ZnO-T networks showed a good response to H2 gas, a change/tune in selectivity to ethanol vapour with a decrease in optimal operating temperature was observed in the networks hybridized with Fe-oxide and Cu-oxide. In case of hybridization with ZnAl2O4 an improvement of H2 gas response (to ≈ 7.5) was reached at lower doping concentrations (20:1), whereas the increasing in concentration of ZnAl2O4 (10:1), the selectivity changes to methane CH4 gas (response ≈ 28). Selectivity tuning to different gases is attributed to the catalytic properties of the metal oxides after hybridization, while the sensitivity improvement is mainly associated with additional modulation of resistance by the built-in potential barriers between n-n and n-p heterojunctions, during adsorption and desorption of gaseous species. Density functional theory based calculations provided the mechanistic insights into the interactions between different hybrid networks and gas molecules supporting the experimentally observed results. The studied materials and sensor structures would provide particular advantages in the field of fundamental research, industrial and ecological applications.

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Section: Gas Sensing Properties Of 3-d Hybrid Ceramic Networkmentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Gas Sensing Properties Of 3-d Hybrid Ceramic Networkmentioning

confidence: 98%

See 2 more Smart Citations

Hybridization of Zinc Oxide Tetrapods for Selective Gas Sensing Applications

Lupan

Postica

Gröttrup

et al. 2017

ACS Appl. Mater. Interfaces

135

111

View full text Add to dashboard Cite

show abstract

“…[37] Also, the hydrogen-gas sensing characteristics were controlled by forming a hole-accumulation layer at the interface between CuO and the gas, which showed dramatic resistance changes between, with and without the hydrogen gas. [38] Furthermore, networked CuO nanowires were demonstrated to enhance the performance of the gas sensor greatly. [36] Copper oxide reacts with reduction gas and also oxidation gas at a suitable temperature.…”

Section: Communicationmentioning

confidence: 99%

Multifurcation Assembly of Charged Aerosols and Its Application to 3D Structured Gas Sensors

et al. 2016

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Multifunctional Materials: A Case Study of the Effects of Metal Doping on ZnO Tetrapods with Bismuth and Tin Oxides

Postica

Gröttrup

Adelung

et al. 2016

Adv Funct Materials

Self Cite

145

111

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Hybrid metal oxide nano-and microstructures exhibit novel properties, which make them promising candidates for a wide range of applications, including gas sensing. In this work, the characteristics of the hybrid ZnOBi 2 O 3 and ZnO-Zn 2 SnO 4 tetrapod (T) networks are investigated in detail. The gas sensing studies reveal improved performance of the hybrid networks compared to pure ZnO-T networks. For the ZnO-T-Bi 2 O 3 networks, an enhancement in H 2 gas response is obtained, although the observed p-type sensing behavior is attributed to the formed junctions between the arms of ZnO-T covered with Bi 2 O 3 and the modulation of the regions where holes accumulate under exposure to H 2 gas. In ZnO-T-Zn 2 SnO 4 networks, a change in selectivity to CO gas with high response is noted. The devices based on individual ZnO-T-Bi 2 O 3 and ZnO-T-Zn 2 SnO 4 structures showed an enhanced H 2 gas response, which is explained on the basis of interactions (electronic sensitization) between the ZnO-T arm and Bi 2 O 3 shell layer and single Schottky contact structure, respectively. Density functional theory-based calculations provide mechanistic insights into the interaction of H 2 and CO gas molecules with Bi-and Sn-doped ZnO(0001) surfaces, revealing changes in the Fermi energies, as well as charge transfer between the molecules and surface species, which facilitate gas sensing.

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Non-planar nanoscale p–p heterojunctions formation in Zn Cu1O nanocrystals by mixed phases for enhanced sensors

Cited by 75 publications

References 74 publications

Hybridization of Zinc Oxide Tetrapods for Selective Gas Sensing Applications

Hybridization of Zinc Oxide Tetrapods for Selective Gas Sensing Applications

Multifurcation Assembly of Charged Aerosols and Its Application to 3D Structured Gas Sensors

Multifunctional Materials: A Case Study of the Effects of Metal Doping on ZnO Tetrapods with Bismuth and Tin Oxides

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