NH3 Gas Sensor Research Articles

Multifunctional sodium alginate fabric based on reduced graphene oxide and polypyrrole for wearable closed-loop point-of-care application

Sodium alginate (SA) fabrics decorated with reduced graphene oxide (rGO) and polypyrrole (PPy) serving as multifunctional materials are prepared by thermal-press reduction and in-situ polymerization. The superior conductivity (0.17 kΩ·sq−1) of SA/rGO/PPy composite fabric is optimized through L9(34) orthogonal experimental design. Microstructures of the resultant SA/rGO/PPy composite fabric are investigated by field emission -scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction measurement, respectively. It is found that SA/rGO/PPy composite fabric possesses not only excellent thermal stability but also mechanical durability. The results of NH3 gas experiments indicate that SA/rGO/PPy composite fabric exhibits reliable linearity of concentration (2–16 ppm) dependency, unique repeatability, a high sensing response (10.7%) at low detection limit of 2 ppm and admirable selectivity. Moreover, SA/rGO/PPy composite fabric acting as a heater can reach to approximately 40–90 ℃ at low voltage of 3 V to 9 V. Hence, the optimum SA/rGO/PPy composite fabric is supposed to be used as ultrasensitive NH3 gas sensor and wearable heater for nephropathy diagnosis purpose and thermo-responsive drug deliver in point-of-care (POC) application to develop a closed-loop treatment.

High performance Cr doped ZnO by UV for NH3 gas sensor

In this work, Cr doped ZnO nanoparticles were synthesized by a hydrothermal method. Ammonia gas (NH3) sensing was tested under UV illumination at room temperature. The irradiation returned the sensor after detecting the NH3 molecules back to their initial states. More importantly, it created the electrons needed to ionize the oxygen molecules absorbed on the surface of the Cr:ZnO nanoparticles. This increase is necessary for the creation of more active surface sites which are necessary for the detection of the NH3 molecular in air. It was found that the increase in the output of doped ZnO nanoparticles sensor is due both to the Cr doping and to the UV irradiation. For a NH3 concentration of 50 ppm, the increase in the signal was 9 %. The results showed that the irradiated Cr doped ZnO nanoparticles have a higher sensitivity for detecting the presence of NH3 gas at room temperature than the undoped and unirradiated ZnO nanoparticles.

High-performance chemiresistor-type NH3 gas sensor based on three-dimensional reduced graphene oxide/polyaniline hybrid

In this study, a novel gas sensor is proposed based on a three-dimensional reduced graphene oxide/polyaniline (3D RGO/PANI) hybrid, which is synthesized by a hydrothermal method for detecting NH3 gas at room temperature. The 3D RGO/PANI hybrid is characterized by field emission-scanning electron microscopy, Fourier transform infrared and x-ray diffraction. The specific surface area is analyzed using the Brunauer–Emmett–Teller (BET) equation. The as-synthesized sensing materials with an appropriate amount of polyaniline nanowires (PANI-NWs) can effectively prevent aggregation of the neighboring graphene sheets and directly act as adsorption sites for NH3 molecules. In comparison with its pure 3D RGO counterpart, the 3D RGO/PANI (1:1) hybrid exhibits 44.7 times enhanced response to 100 ppm NH3, suggesting the remarkable effect of PANI-NWs in improving the sensitivity. This work gives new insights into boosting the sensitivity and selectivity of detecting NH3 gas by incorporating PANI-NWs into 3D RGO.

Anti-biofouling NH3 gas sensor based on reentrant thorny ZnO/graphene hybrid nanowalls

Since toxic gas leakage may cause ecological environmental problems and even life-threatening damage, effective monitoring of toxic gas is of great importance and subject to increasing demand. However, complicated environmental factors, as well as various coexisting interferences can easily affect the sensitivity and selectivity of gas sensors, hindering their performance. Recent reports have successfully demonstrated the development of hierarchical nanostructures with desirable self-cleaning properties, yet gas sensors that can resist contamination have rarely been realized. Here, we developed a reentrant thorny ZnO/graphene hybrid nanowall structure that simultaneously repels liquid contamination and possesses NH3 gas sensing properties. The unique reentrant and hierarchical structure, featuring an interconnected vertical graphene nanowall framework with numerous ZnO nanospikes branched on the top nanowall, is highly repellent to liquids, even biofluids with low surface tension. The hierarchical structure consisting of gas sensing graphene and ZnO can be successfully applied as an NH3 gas sensor at room temperature, exhibiting not only excellent sensitivity, selectivity, and repeatability, but also outstanding stability even after bacterial contamination. This study provides a versatile method for fabricating reentrant and hierarchical structures with excellent liquid repellency, and offers a promising method for designing reliable gas sensors with anti-biofouling properties.

Effect of LiF on the ion conductivity and sinterability of (Al0.2Zr0.8)20/19Nb(PO4)3 solid electrolyte

The (Al0.2Zr0.8)20/19Nb(PO4)3 was fabricated by high temperature solid reaction method, and the sintering property and electrochemical property of the electrolyte were improved by adding LiF as a sintering aid. The phase composition, microstructure and electrical conduction property of the (Al0.2Zr0.8)20/19Nb(PO4)3 were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The results show that the compactness of electrolyte was improved by LiF addition. When the addition amount of sintering aid LiF is 4 wt%, the electrolyte has the highest density and conductivity, and its conductivity reaches 2.45 × 10−3 S.cm−1 at 500 °C, which is 11.1 times as high as that of sample without LiF addition. The ionic transfer numbers of the electrolyte measured by DC polarization method are above 0.999, indicating that the solid electrolyte nearly is pure Al3+ ion conduction and the electronic conduction may be ignored. On the basis of (Al0.2Zr0.8)20/19Nb(PO4)3 with 4 wt% LiF electrolyte and CrVO4 sensing material, a mixed potential type of NH3 gas sensor was prepared and tested. The NH3 gas sensor displays excellent sensing performance with a sensitivity of 90.2 mV/decade at 300 °C.

High performance ammonia gas sensor based on GaN honeycomb nanonetwork

In this work, we have demonstrated a FET-like ammonia (NH3) gas sensor fabricated on a unique structure namely GaN honeycomb nanonetwork (GaN-HN) which is in-plane electrically conductive together with large surface-to-volume ratio. Utilizing ohmic contact Ti/Al/Ti/Au multilayers as the source and the drain terminals and Pt nanonetwork layer as the gate terminal, the FET-like NH3 gas sensors were fabricated by a two-mask photolithography process. The fabricated NH3 gas sensors have high selectivity, fast response/recovery, and a wide detection range up to 5000 ppm. The response and recovery time for 5 ppm NH3 gas are 23 s and 101 s at a moderate operating temperature of 120 °C. Interestingly, this sensor is capable to detect trace NH3 gas and the low limit of detection (LOD) is as small as 0.31 ppm. Its absorption activation energy Ea is also investigated by the transient-state study.

NiCo2O4 functionalized with rGO catalyst as an active layer for ammonia sensing

Spinel NiCo2O4 material has received considerable attention as an excellent gas sensing material. In this study, we report facile and hydrothermal method synthesis for preparing mesoporous NiCo2O4 and its composite with reduced graphene oxide (rGO) by wet impregnation method. The as-prepared samples were subjected to structural and morphological investigations. The constructed NiCo2O4-rGO composite gas sensor shows superior NH3 gas sensing performance at room temperature and the response for 100 ppm NH3 is 1.068 at room temperature. Moreover, this sensor shows better gas sensing performances with fast response times, recovery times, and good repeatability for a test period of 10 cycles along with high selectivity for NH3 gas sensor. Thus, NiCo2O4-rGO composite may be used as an efficient NH3 gas sensor. The sensing mechanism of the NiCo2O4-rGO composite sensors has also been proposed in this paper.

Ultrasensitive flexible NH3 gas sensor based on polyaniline/SrGe4O9 nanocomposite with ppt-level detection ability at room temperature

Detection limit as an important parameter of gas sensors, much effort has been devoted to developing high-performance gas sensors with low detection limit. However, the development of gas sensors with ppt-level detection limit still faces enormous challenges. In this work, a flexible and ultra-highly sensitive ammonia (NH3) sensor based on polyaniline/SrGe4O9 nanocomposites (PSN) was successfully fabricated via a facile in situ chemical oxidation polymerization method. When exposed to 0.2–10 ppm NH3 at 25 °C in 60% relative humidity (RH), the PSN sensor showed larger sensitivity (20.59% ppm−1) than that of PANI sensor (9.82% ppm−1). The response of the PSN sensor (16%) was two-fold higher than that of the PANI one (8%) to 0.2 ppm NH3 at room temperature. Meanwhile, the response time of the PSN sensor (24 s) was reduced to up to a third of that of the PANI sensor (64 s) for 800 ppb NH3. Additionally, the flexible PSN sensor exhibited good reproducibility, satisfactory long-term stability, excellent selectivity and outstanding flexibility to NH3 at room temperature. Significantly, the PSN sensor presented the ultra-low detection limit of 250 ppt toward NH3. Such outstanding gas-sensing properties were attributed to the unique hierarchical architecture with abundant mesoporous and the formation of p-n heterojunction at the interface between p-type PANI and n-type SrGe4O9. This research provides new strategies for developing high-performance NH3 sensors with supersensitive and ultra-low detection limit.

Highly Water Durable Solid Electrolyte Type Ammonia Gas Sensor with Ammonium Lanthanum Niobate As an Auxiliary Sensing Electrode

Ammonia (NH3) gas is one of the toxic gases causing a serious health damage, while NH3 is a useful chemical in industrial field. Therefore, for preventing unexpected accidents caused by inhalation, rapid, continuous, and reliable NH3 detection is greatly required by applying smart gas sensor which can put every NH3 emitting site. Among the various kinds of NH3 gas detection tool, the solid electrolyte type sensor is regarded to be a promising candidate for on time monitoring tool due to its selective and quantitative gas detection, thermal stability, and compactness in size, if both the low-temperature sensor operation and satisfactory water durability are realized.In 2011, we have reported a solid electrolyte type NH3 gas sensor showing high water durability at 230°C by using Al3+ ion conducting (Al0.2Zr0.8)20/19Nb(PO4)3 solid electrolyte and water durable NH4 +-β-gallate auxiliary sensing electrode. However, the operation temperature of this sensor (230°C) at which the high sensitivity without electrical noise was obtained are still high for expecting a long-term sensor operation, and it is required to lower the operation temperature. Because a main reason for preventing the low-temperature operation is high electrical resistance of NH4 +-β-gallate, we can expect to lower the operation temperature by newly designing an auxiliary sensing electrode.In this study, we focused on NH4LaNb2O7 in which NH4 + ions existed stably in the layered structure, similar to the NH4 +-β-gallate solid, and fabricated the highly water durable NH3 gas sensor which can operate even at 180°C, by combining with (Al0.2Zr0.8)20/19Nb(PO4)3 solid electrolyte.The NH4LaNb2O7 solid was obtained by the ion-exchange of RbLaNb2O7, which was synthesized by conventional solid-state reaction, in NH4NO3 eutectic solution. Similar to our previous sensor, the sensor element was devised by the combination of (Al0.2Zr0.8)20/19Nb(PO4)3 solid electrolyte, NH4LaNb2O7 auxiliary sensing electrode, and Al metal reference electrode. The NH3 gas sensing performances were investigated at 180°C in atmospheres whose water content was varied from 0 to 4.2 vol.%.From the thermal analysis of the synthesized NH4LaNb2O7 solid, it was found that NH4 + ions stably existed in (NH4)LaNb2O7 solid up to 200°C. Therefore, we decided the sensor operation temperature at 180°C which is slightly lower than the upper temperature limit of NH4LaNb2O7 solid for holding NH4 + ions in its structure. The present sensor exhibited a stable and continuous sensor response to NH3 gas concentration change with a 90% response time of 6 minutes (Response time includes substitution time of test gas in the gas flow line) at 180°C even under humid atmosphere containing 4.2 vol% H2O. Furthermore, the sensor EMF outputs for each NH3 gas concentration were almost same even for varying humidity from 0 to 4.2 vol%, and the EMF changes by changing NH3 gas concentration obeyed a theoretical Nernst relationship over three months, indicating that the present sensor with NH4LaNb2O7 solid as an auxiliary sensing electrode showed the theoretical response for NH3 gas at 180°C with long term stability even in humid atmosphere.

Sensitized Surface Acoustic Wave (SAW) Sensors for Room-Temperature Gas Detection

IntroductionIdentifying and quantifying gas components in mixtures is an important direction for the development of gas sensors.So far, many types of gas sensors have been developed, which can be mainly classified into semiconductor, catalytic combustion, and electrochemical, solid electrolyte, infrared optical, quartz crystal microbalance type (QCM), surface acoustic wave type (SAW) [1-4], according to the detection mechanism of the sensor.The semiconductor sensor relies on the change of the resistance of the sensitive film, and has nothing to do with the mass of the film. Combining sensor arrays and pattern recognition algorithms, identification of mixed atmospheres has been achieved. Conversely, the QCM sensor depends on the change of the film mass, and has nothing to do with the resistance. Recently, Wang et al. achieved NH3 and H2S sensing based on QCM sensor, and each gas concentration can be quantified individually.[5] The QCM sensor is based on Janus mesoporous carbon/silica films with asymmetric mesostructures and disparate active sites (–NH2 and –COOH groups). However, SAW based gas sensors have mass loading effects, acoustoelectric effects and elastic loading effects.[6]Here, we investigate the NO2 and NH3 detection and mechanisms at room temperature of surface acoustic wave sensors based on Bi2S3 nanobelts. When exposed to NO2, the acoustic and electrical effects dominate. When exposed to NH3, the mass loading effects dominate. Bi2S3-based semiconductor and QCM sensors were used to demonstrate this effect.ExperimentBi2S3 nanobelts were prepared using a hydrothermal method. Briefly, triphenyl bismuth (C18H15Bi, 98%, Aladdin, 0.6 mM) and dibenzyl disulfide(C6H5CH2SSCH2C6H5, 98%, Aladdin, 0.6 mM) were dissolved in 4 ml oleylamine (OLA), and then 0.4 g polyvinyl pyrrolidone (PVP,Aladdin, MW ≈ 24,000-28,000) were dissolved into 26 ml absolute ethanol. After that, these solutions were thoroughly mixed together and transferred into a 50 ml autoclave to react at 180oC for 8 hours. Finally, the product was washed with hexane and dissolved in ethanol at a concentration of 30 mg/mlfor use.In this study, lithium niobate is chosen as the piezoelectric substrate for making the SAW delay-line device. For the sensitive layer deposition, 100 µL of Bi2S3 nanobelts solution was spin-coated (at a speed of 2000 rpm) onto the sensitive area of the SAW resonator as a gas sensing film. The central frequency of SAW delay-line device was measured using a network analyzer.Results and ConclusionsBi2S3/SAW gas sensor showed a response of 5 kHz toward 20 ppm of NO2, and 12 kHz upon 20 ppm NH3 at room temperature, with fast response and recovery speed, respectively. Bi2S3 nanobelts can be used as a sensitive material for high performance NH3 and NO2 gas sensors. The semiconductor type and QCM type gas sensor were used to explain the sensitive mechanism. This provides a reference for us to use different mechanisms to make different types of sensors, and recognize and quantify gas components in mixtures.

Synthesis of Psi/CuO/Cu2o Heterostructure for NH3 Vapor Detection at Room Temperature

In this paper, we demonstrate the use of the heterostructure porous silicon PSi-n/CuO-p/Cu2O-n as an alternative structure for an efficient gas sensor for NH3 sensing. The porous silicon PSi was prepared using an electrochemical method and utilized as a substrate. Then, CuO homogeneous thin films were synthesized by thermal evaporation/oxidation on the pre-prepared PSi substrate, on which a uniform layer of Cu2O is deposited by electrodeposition method. The structural, morphological and optical characterizations of the obtained CuO and Cu2O films were carried out by XRD, SEM, FTIR, UV spectroscopy and contact angle measurements. Likewise, the electrical properties of CuO-p/Cu2O-n thin films, deposited on PSi-n, were studied by current-voltage (I-V) measurements at room temperature, within the sandwich (semiconductor/oxide/oxide) configuration. The NH3 gas sensing characteristics: response/recovery time, sensitivity and repeatability, were evaluated and tested at different gas concentrations at room temperature, allowing the determination of the different parameters of the heterojunction PSi/CuO/Cu2O.These results indicated that the PSi/CuO/Cu2O structure is a promising candidate for reliable high-performance NH3 gas sensors at room temperature, with a very high sensitivity to NH3 (80%) and with an extremely fast response time of the order of 1 second. These sensing performances enhancements at room temperature are due to the high surface area to volume ratio of PSi and the use of PSi/CuO/Cu2O heterostructure. The prospective sensing mechanism of the presented sensor has been discussed.

A one-pot hydrothermal-induced PANI/SnO2 and PANI/SnO2/rGO ternary composites for high-performance chemiresistive-based H2S and NH3 gas sensors

We have fabricated the PANI/SnO2 and PANI/SnO2/rGO ternary composites by facile one-step hydrothermal approach followed by polymerization method. The hybrid nanocomposites were scientifically investigated for their structural, morphological and elemental composition through XRD, TEM, EDAX, FTIR and EPR analysis. The tetragonal rutile phase with nanospherical morphology sizes in the range of 25–35 nm was investigated by XRD and TEM results. The N2 adsorption–desorption measurement showed that ternary PANI/SnO2/rGO composite showed huge specific surface area (114.51 m2/g) and pore size (17–21 nm), which is higher than the bare SnO2 (surface area = 83.51 m2/g; pore size = 33–37 nm). The chemiresistive-type gas sensor was fabricated and the designed sensors were investigated by their sensing responses towards different gases (ethanol, methanol, carbon monoxide, oxygen, H2S and NH3). The results exposed that the ternary PANI/SnO2/rGO showed high sensing response (56%), fast response (35 s) and recovery time (40 s) towards H2S gas than other gases. The improved gas-sensing mechanism was also proposed.

Room temperature ammonia sensing based on graphene oxide integrated flexible polyvinylidenefluoride/cerium oxide nanocomposite films

ABSTRACT In this work, novel room temperature (RT) ammonia (NH3) sensors comprising graphene oxide (GO) integrated polyvinylidenefluoride (PVDF)/cerium oxide (CeO2) nanocomposite films have been prepared via simple solution casting technique. The structural and morphological characteristics of flexible tertiary PVDF/CeO2/GO nanocomposite films have been investigated using various analytical techniques and their NH3 gas-sensing performance was evaluated at RT and the relevant sensing mechanism was established. The flexible PVDF/CeO2/GO nanocomposite films responded strongly to NH3 gas with enhanced gas sensing properties at RT as compared with various other volatile organic compounds (VOCs) such as acetone, ethanol, formaldehyde and toluene.

Precise preparation of WO3@SnO2 core shell nanosheets for efficient NH3 gas sensing

Development of high-performance ammonia (NH3) sensor is imperative for monitoring NH3 in the living environment. In this work, to obtain a high performance NH3 gas sensor, structurally well-defined WO3@SnO2 core shell nanosheets with a controllable thickness of SnO2 shell layer have been employed as sensing materials. The prepared core shell nanosheets were used to obtain a miniaturized gas sensor based on micro-electro-mechanical system (MEMS). By tuning the thickness of SnO2 layer via atomic layer deposition, a series of WO3@SnO2 core-shell nanosheets with tunable sensing properties were realized. Particularly, the sensor base on the fabricated WO3@SnO2 nanosheets with 20-nm SnO2 shell layer demonstrated superior gas sensing performance with the highest response (1.55) and selectivity toward 15 ppm NH3 at 200 °C. This remarkable enhancement of NH3 sensing ability could be ascribed to the formation of unique WO3-SnO2 core-shell heterojunction structure. The detailed mechanism was elucidated by the heterojunction-depletion model with the help of specific band alignment.

Facile synthesis of ultrafine rGO/WO3 nanowire nanocomposites for highly sensitive toxic NH3 gas sensors

We introduce a facile and scalable synthesis of rGO/WO3 nanocomposites by hydrothermal method for gas sensing applications. The characterization of rGO/WO3 nanocomposites by some advanced techniques such as scanning electron microscopy, high resolution transmission electron microscopy and Raman spectroscopy revealed that high quality rGO/WO3 nanocomposites included single crystal WO3 nanowires (average diameter of 10 nm) entangled by thin rGO layers. Sensing measurements demonstrated that the rGO/WO3 nanocomposite-based sensor can detect highly toxic NH3 gas at low concentrations ranging from 20 ppm to 500 ppm and fulfills practical applications. The developed gas sensors based on rGO/WO3 nanocomposites have significant application prospects in environment pollution monitoring at detection limit of about 138 ppb. We also discussed the gas sensing mechanism of the rGO/WO3 nanocomposites based on the p-n junction.

Trace level toxic ammonia gas sensing of single-walled carbon nanotubes wrapped polyaniline nanofibers

This paper presents a two-step enhancement and a comprehensive analysis of single-walled carbon nanotubes (SWCNTs) wrapped polyaniline nanofiber (NPANI) ammonia (NH3) gas sensor at room temperature. SWCNT-PANI composites are successfully synthesized using an efficient and cost-effective rapid in situ chemical polymerization method. The structural morphology and modification of the samples are characterized using field-emission scanning electron microscopy and HRTEM. FTIR and Raman spectroscopic studies are also performed to gain a better insight into the chemical environmental interaction in the as-prepared nanocomposite. The analysis confirms the successful formation of the nanocomposite. The observed NH3 gas-sensing response at 10 ppm of SWCNT, f-SWCNT (functionalised SWCNT), and SWCNT-PANI composite sensors are 5%–6%, 18%–20%, and 24%–25%, respectively. The SWCNT-PANI composite sensors have shown higher repeatability, selectivity, long-term stability, and fast response-recovery characteristics as compared to f-SWCNTs and pristine SWCNT sensors. Concentration and temperature dependent gas-sensing studies are also analyzed. The sensor response also shows a linear relationship with NH3 gas concentration and an inverse relationship with increasing temperature.

Flexible ZnO/PANI/nonwoven nanocomposite based high-sensitive NH3 gas sensor via vapor phase polymerization method

A new synthetic method to flexible sensor towards NH3 with response magnitude as high as 4300% was based on vapor phase polymerization (VPP), where zinc oxide (ZnO) sheets were exposed to polyaniline (PANI) vapors on the flexible nonwoven fabric substrate. A possible brick wall masonry assembly structure of ZnO and PANI on the surface of nonwoven fabric was provided, which also possessed excellent mechanical flexibility and thermostability. The response value of flexible ZnO/PANI/nonwoven sensor increased from 5% to 4300% with the NH3 concentration varied over a wide range (0.5–10 ppm) at room temperature. Flexible and conductive ZnO/PANI/nonwoven composite material has good potential applications as NH3 gas sensor in environment monitoring components and wearable flexible devices.

Solvothermally Synthesized Nickel Doped Tin Dioxide based Thick Films for H2 and NH3Gas Sensing

Abstract Economical fabrication of semiconductor nanomaterials based gas sensor operating at relatively low temperature is very essential. Herein, nanostructured NixSn1-xO2 (where x = 0, 0.01, 0.05 and 0.1) powders were synthesized using facile solvothermal method at 200 °C for 24h. These powders were characterized using various analytical techniques viz. X-ray diffractometry, scanning electron microscopy, field emission transmission electron microscopy to understand their physico-chemical properties. Thick film pastes were formulated for the synthesized nanopowders. The thick films were printed on to glass substrates and fired at 400 C for 1h. The gas sensing performance of the resultant thick films was studied for hydrogen and ammonia. Thick film gas sensor based on Ni0.01Sn0.99O2 nano powder exhibited highest responseto hydrogen gas at lowest operating temperature (78 °C). On the other hand, the highest response to ammonia gas at lowest operating temperature (74 °C) was obtained in case of thick film gas sensor fabricated using nano powder of Ni0.1Sn0.90O2

Fabrication of Highly Sensitive NH3 Sensor Based on Mixed In2O3 – AgxO Nanostructural Thin Films deposited on porous silicon

A highly sensitive NH3 gas sensor of mixed In2O3 – AgxO nanostructure thin films deposited on porous silicon were synthesized by chemical spray pyrolysis technique. The structure of the sensor thin films is analyzed by XRD, AFM and FE-SEM techniques. The nanostructure polycrystalline thin films with average grain size between (93.56 and 57.75) nm, from AFM results. The sensitivity of the synthesized gas sensors toward 400 ppm NH3 is obtained a high value in the low operating temperature, which ranged between (77.57%-98.66%) with low response and recovery times, ranged between (11.9-15.19) s and (8.6-25.22) s respectively. These high sensor properties are due to the porous silicon substrate.

Preparation and NH3 Gas-Sensing Properties of Double-Shelled Hollow ZnTiO3 Microrods.

A novel double-shelled hollow (DSH) structure of ZnTiO3 microrods was prepared by self-templating route with the assistance of poly(diallyldimethylammonium chloride) (PDDA) in an ethylene glycol (EG) solution, which was followed by calcining. Moreover, the NH3 gas-sensing properties of the DSH ZnTiO3 microrods were studied at room temperature. The morphology and composition of DSH ZnTiO3 microrods films were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The formation process of double-shelled hollow microrods was discussed in detail. The comparative gas-sensing results revealed that the DSH ZnTiO3 microrods had a higher response to NH3 gas at room temperature than those of the TiO2 solid microrods and DSH ZnTiO3 microrods did in the dark. More importantly, the DSH ZnTiO3 microrods exhibited a strong response to low concentrations of NH3 gas at room temperature.