Ppm NH3 Research Articles

One-step laser ablation of Fe clusters supported on Ti3C2Tx nanosheets for enhanced NH3 sensing at room temperature

Supported metal clusters, different from single-atom and large metal-nanoparticle catalysts, possess distinct geometric and electronic structures and effective catalytic sites and thus exhibit unique catalytic activity. Here, an environment-friendly and effective method of using one-step pulsed laser ablation in liquid is reported for synthesizing the emerging gas-sensing materials of the Fe clusters supported on Ti3C2Tx MXene (L-Fe-Ti3C2Tx). Then, the sensors based on the L-Fe-Ti3C2Tx nanosheets are subsequently developed for the real-time detection of ammonia at room temperature. Moreover, it was found that the response of the L-Fe-Ti3C2Tx-232 sensor (in a synthesis condition) toward 10 ppm NH3 is improved to 64.03%, yet remains 39.19%, and exhibits significant repeatability even at high humidity, which makes it become a promising candidate in some special scenarios such as agriculture or human health applications. The excellent NH3-sensing properties can be attributed to the abundance of defective sites with stronger adsorption and the catalysis of the Fe clusters supported on the Ti3C2Tx nanosheets. This work may provide an effective methodology for the confinement of non-noble metal clusters on two-dimensional (2D) materials to further improve the performance of the gas sensors based on 2D materials.

Flame-retardant fibre-particle-polymer semiconductive networks for physically transient supercapacitors and chemiresistors

With fast development of green economy and carbon neutral society, biodegradable and sustainable materials are urgent needed for multifunctional transient electronics. Here, a flexible, green and flame-retardant fibre-particle-polymer network is developed for physically transient supercapacitors and chemiresistors. By regulating 1D-0D-2D ternary interface, micro/nanoarchitectured polyaniline/ink/alginate semiconductive network enables effective electrolyte infiltration and abundant surface adsorption and diffusion. Moreover, the 0D ink particles promote interface bonding between 1D alginate fibres and 2D polyaniline, giving rise to better wear resistance, compression-after-impact strength and electrical conductivity. As expected, the transient supercapacitor delivers high areal capacitance of 134.1 mF cm−2, and the transient gas sensor exhibits desirable response (33 %) and long-term stability (56 days) toward 40 ppm NH3 at room temperature, which is superior to most of previous reports. This work pushes forward a significant step towards fibre-particle-polymer interfacial design of physically transient electronics and shows great potential in flexible platform based on comfortable biofibers.

Pt/MoS2/Polyaniline Nanocomposite as a Highly Effective Room Temperature Flexible Gas Sensor for Ammonia Detection.

A Pt/MoS2/polyaniline (Pt/MoS2/PANI) nanocomposite is successfully synthesized by the hydrothermal process combined with the in situ polymerization method, and then Pt particles are decorated on its surface. The Pt/MoS2/PANI nanocomposite is deposited on a flexible Au-interdigitated electrode of a polyimide (PI) film. The flexible sensor exhibits a higher response value and fast response/recovery time to NH3 at room temperature (RT). It results in 2.32-fold and 1.13-fold improvement in the gas-sensing response toward 50 ppm NH3 compared to those of PANI and MoS2/PANI-based gas sensors. The detection limit is 250 ppb. The enhancement sensing mechanisms are attributed to the p-n heterojunction and the Schottky barrier between the three components, which has been confirmed by the current-voltage (I-V) curves. A satisfactory selectivity to NH3 against trimethylamine (TMA) and triethylamine (TEA) is obtained according to density functional theory (DFT), Bader's analysis, and differential charge density to illustrate the adsorption behavior and charge transfer of gas molecules on the surface of the sensing materials. The sensor retains the excellent sensing response value even under high relative humidity and sensing stability at higher bending angle/numbers to NH3 gas. Hence, Pt/MoS2/PANI can be regarded as a promising sensing material for high-performance NH3 detection at room temperature applied in flexible wearable electronics.

One-step preparation of flexible citric acid-doped polyaniline gas sensor for ppb-level ammonia detection at room temperature

In this work, a citric acid-doped polyaniline/polyvinylidene fluoride (CPP) flexible ammonia sensor was prepared by in situ oxidative chemical polymerization on a flexible porous polyvinylidene fluoride membrane. The CPP sensor exhibited excellent performance at room temperature (217% response for 1 ppm NH3), low detection limit (LOD) reaches 3 ppb, and rapid response and recovery times (30 s /195 s for 1 ppm NH3, respectively). Furthermore, the sensor shows outstanding flexibility and excellent stability. After 10,000 bending cycles, the CPP sensor still produces over 99% stable response. The response reached 95% of its initial value after more than 60 days of storage. The CPP sensor exhibits excellent gas-sensing performance for ammonia gas, mainly attributed to the increase in active sites induced by citric acid doping and the synergistic effect of the porous substrate. The above results demonstrated that the CPP flexible film sensor is a high-performance candidate for enhanced ammonia gas sensing properties at room temperature.

Effect of MWCNTs Incorporation Into Polypyrrole (PPy) on Ammonia Sensing at Room Temperature

We reported the gas sensing properties of nanocomposites of polypyrrole (PPy) and multiwalled carbon nanotubes (MWCNTs) made with two incorporation techniques, i.e., ex situ and in situ polymerization. The pure PPy and PPy-MWCNT nanocomposites prepared by both techniques were characterized by field emission scanning electron microscopy (FESEM), Raman, and Fourier transform infrared spectroscopy (FTIR). The good dispersion was confirmed for the MWCNTs into PPy matrix prepared via in situ technique. Furthermore, the gas sensing measurements of pure PPy and ex situ synthesized PPy-MWCNT nanocomposite were carried out for the case of NH3 at room temperature, and they revealed a slight increase in response for PPy-MWCNT (1.5 wt%) sample. Then, different mass ratios of MWCNTs (0.5–3.5 mg) were incorporated into PPy matrix via in situ polymerization, and sensing toward NH3, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}_{{2}}\text{H}_{{5}}$ </tex-math></inline-formula> OH, and CO2 was investigated. The in situ prepared PPy-MWCNT (2.5 mg) composite showed superior sensing with 1.33%–29.74% response for 5–200 ppm NH3, 47/111 s as response/recovery time, high selectivity, and good repeatability toward NH3.

Room‐Temperature NH3 Sensor Based on SnO2 Quantum Dots Functionalized SnS2 Nanosheets

AbstractTraditional metal oxide semiconductor gas sensors are facing significant challenges for portable devices and integration due to large power consumption caused by high working temperature. 2D nanomaterials with large specific surface areas, rich active sites, and tunable electrical properties are proved to be promising candidates for room‐temperature gas sensors. However, several disadvantages including weak response, sluggish response/recovery kinetics, and poor selectivity still need to be overcome for high‐performance gas sensors. Herein, SnO2 quantum dots (QDs) with a diameter of ≈3 nm functionalized SnS2 nanosheets with a thickness of ≈17 nm are synthesized via a two‐step solvothermal method, which exhibits a high response of 11.1 to 100 ppm NH3 at room temperature of 25 °C with fast response speed and good repeatability, high selectivity, and long‐term stability. The sensing mechanism is mainly ascribed to 0D/2D heterostructure, synergistic effect, and n‐n heterojunction constructed across the interfaces between SnO2 QDs and SnS2 nanosheets. The as‐prepared nanomaterials may contribute to the reasonable design of heterostructure between 0D QDs and 2D nanomaterials, and offer a promising candidate for room‐temperature NH3 detection.

Highly Selective Room Temperature Detection of NH3 and NOx Using Oxygen-Deficient W18O49-Supported WS2 Heterojunctions

In this paper, we reported the controlled synthesis of tungsten disulfide/reduced tungsten oxide (WS2/W18O49) heterojunctions for highly efficient room temperature NOx and ammonia (NH3) sensors. X-ray diffraction analysis revealed the formation of the oxygen-deficient W18O49 phase along with WS2. Field-emission scanning electron microscopy and transmission electron microscopy displayed the formation of WS2 flakes over W18O49 nanorods. X-ray photoelectron spectroscopy showed the presence of tungsten in W4+, W5+, and W6+ oxidation states corresponding to WS2 and W18O49, respectively. The WS2/W18O49 heterojunction sensor exhibited sub-ppm level sensitivity to NOx and NH3 at room temperature. The heterojunction sensor detected 0.6 ppm NOx and 0.5 ppm NH3, with a corresponding response of 7.1 and 3.8%, respectively. The limit of detection of the sensor was calculated to be 0.05 and 0.17 ppm for NH3 and NOx, respectively. The cyclic stability test showed that the sensor exhibited high stability even after 24 cycles for the detection of NH3 and 14 cycles for NOx. Compared to pristine WO3 and WS2, the WS2/W18O49 heterojunction showed high selectivity toward NOx and NH3. The results could be useful for the development of room temperature NOx and NH3 sensors.

Novel SnO2/PAni nanocomposites for selective detection of ammonia at room temperature

The present study aims to investigate a new method of SnO2/polyaniline (PAni) nanocomposite sensor fabrication for detection of ammonia at different temperatures including the room one. The fabrication of composite is performed by synthesis of PAni according to oxidative polymerization. Then the SnO2/PAni hybrid nanocomposites containing different percentages of polymer were fabricated by a deposition–precipitation method in presence of SnCl4 solution. The produced powders were characterized by XRD, BET, FTIR, Raman, TGA and FESEM tests. By increasing PAni contents of the nanocomposites, SnO2 crystallite sizes decrease, the surface area increases, and thermal stability improves. The sensing behavior of SnO2/0–30 wt% PAni in presence of 100–500 ppm ammonia was measured. The SnO2/8 wt% PAni shows the best sensitivity, where the response of sensor for 100 ppm NH3 at room temperature is about 187 %. Optimum heteronucleation and decoration of SnO2 on PAni surface enhances the response. Moreover, the sensor is selective in presence of interfering gases including CO, ethanol, methane, toluene and trichloroethylene.

A novel flexible substrate-free NH3 sensing membrane based on PANI covered rGO functionalized fiber

To alleviate the lack of sensors on the Internet of Things (IoT), a novel flexible substrate-free sensing membrane has been put forward, of which the fabrication is simple, low-cost and has potential of large-scale production via a vacuum filtration method. After alkaline hydrolysis, paper fibers were covered with reduced graphene oxide (rGO) and further functionalized with a layer of polyaniline (PANI) by in-situ polymerization. The rGO functionalized fiber (GF) played a competent role as the embedded conductive network, efficiently transferring the charge signal from the surface sensing layer. Eventually, the functionalized fibers were re-filmed under a 0.1 MPa negative pressure by vacuum filtration method. The surface area of the film was about 23.76 cm2 and 1 × 1 cm2 square was cut for the following test. The sensing membrane based on PANI covered rGO functionalized fiber (PGF) has shown superb sensing performance to NH3, with excellent stability, selectivity and sensitivity at room temperature. The linear response range of sensor based on PGF was 25 ppm, the correlation coefficient was 0.9908 and the limit of detection (LOD) was 34 ppb. The response to NH3 was ∼14% while the responses of other testified interfering gases were all below 0.5%. Most importantly, the sensing membrane has exhibited an excellent capability of resisting bending, and maintained the response to 10 ppm NH3 (13.55–14.3%) even after 1200 bends, indicating that the sensor has a bright prospect of future wearable applications.

3D substoichiometric MoO3−x/EGaln framework for room temperature NH3 gas sensing

Though conventional metal oxide-based NH3 gas sensors possess the advantage of simplicity and high sensitivity, their relatively high operating temperature still limits their widespread applications. Therefore, it is essential to develop a reliable NH3 sensor that operated at room temperature. In this context, we employ the ultrasonic method to coat the sonication-prepared substoichiometric molybdenum trioxide (MoO3−x) nanosheets upon the eutectic gallium indium (EGaIn) microdroplets, thus forming a three-dimensional (3D) MoO3−x/EGaIn semiconducting liquid metal framework. Due to the high surface-reducing properties of EGaIn, the concentration of oxygen vacancies in MoO3−x is further increased, presenting enhanced surface plasmon resonance in the visible light range. Such a plasmonic oxide framework (POF) exhibits a response magnitude of 1.22 for 50 ppm NH3 at room temperature with almost complete recovery, high selectivity, and excellent repeatability under the blue light excitation. It is remarkable that room temperature optoelectronic gas sensing performance is rarely seen in pure metal oxides. This work not only provides a promising NH3 gas sensing material but also demonstrates the great potential of liquid metal/semiconductor contacts for room temperature reversible gas sensing.

Dual Activation and Photocatalyst-Induced Selective Detection in Defect Tuned Pd–ZnO Thin Films for Low ppm Detection of CH and CO

The selectivity of CO and CH4 remains a hurdle to researchers working on metal-oxide-based sensors, as the sensing mechanism is analogous for both gases. With this objective, an attempt has been made to realize selective sensing of CH4 (up to 1 ppm) and CO (up to 1 ppm) by introducing a selective photocatalyst layer (Zn5(OH)8Cl2.H2O) on Pd–ZnO. It has been noticed that the incorporation of a photocatalytic layer is found to be highly efficacious in providing the sensor with a strong absorption reaction and propelling the surface conversion kinetics. The role of dual activation and photocatalytic activity in selectivity along with tunability is also explored in this work. The dual activation incorporates the benefits of both temperature and optical excitation on metal-oxide-based sensors, highlighting the innumerable advantages and nullifying the disadvantages of both methods. Tunable and selective sensing with a response time/recovery time of 40 s is explicated. The method for improving the sensing performance of Pd–ZnO–photocatalyst-based nanostructures in terms of repeatability and cross sensitivity with respect to 1 ppm of CO, 1 ppm of CH4, 1 ppm of NH3, 250 ppm of CO, and 40% of O2 is discoursed. It has been observed that the sensor with a sensitivity of 23%/ppm for CH4 and 93%/ppm for CO with a minimum baseline drift of less than 3% is achieved. The long-term stability and repeatability of dual-activated sensors are also verified, and less than 3% change has been noticed. The work can be extended for the selectivity of other metal oxides as well.

Gas Sensing Properties of Pure and Co Surface Modified Nanocrystalline SmFeO3 Thick Films

In present work, nanocrystalline SmFeO3 perovskite oxide powder was prepared by sol-gel method. Thick films of SmFeO3 were fabricated onto a glass substrate by screen printing technique and heated at 500 ºC for 30 min. As-prepared pure nanocrystalline SmFeO3 thick films were dipped into 0.1 M aqueous solution of cobalt chloride for different intervals of time. Microstructure and surface morphology of both pure and Co surface modified SmFeO3 thick films were investigated by energy dispersive X-ray analysis (EDAX) and field effect scanning electron microscopy (FE-SEM) techniques. The FE-SEM micrograph reveals the porous nature of thick films. EDAX analysis showed that both pure and Co modified thick films are oxygen deficient. Gas sensing performance of these films was tested for different gases. The highest response and selectivity was recorded to 50 ppm NH3 gas at 200 ºC for SmFeO3 thick film dipped into cobalt chloride solution for 3 min. The effect of cobalt doping and its dipping time on microstructure, surface morphology and gas sensing properties of pure SmFeO3 thick film was discussed.

Unique modulation effects on the performance of graphene-based ammonia sensors via ultrathin bimetallic Au/Pt layers and gate voltages.

Gas sensors with superior comprehensive performance at room temperature (RT) are always desired. Here, Au, Pt and Pt/Au-decorated graphene-based field effect transistor (FET) sensors for ammonia (denoted as Au/Gr, Pt/Gr and Pt/Au/Gr, respectively) are designed and fabricated. All these devices exhibited far better RT sensing performances for ammonia compared with graphene devices. Applying positive back gate voltages can further enhance their RT performance in which the Pt/Au/Gr devices show superior RT comprehensive performance such as a response of -16.2%, a recovery time of 4.6 min, and especially a much reduced response time of 54 s for 200 ppm NH3 with a detection limit of 103 ppb at a gate voltage of +60 V, and can be potentially tailored for further performance improvement by controlling the ratios of Pt and Au. The dependences of their performance on the gate voltage except for the response time could be reasonably explained by theoretical calculations in terms of the changes of the total density of states near the Fermi level, adsorption energies, transferred charges and adsorption distances. This study provides an effective solution for performance improvement of FET-based sensors via synergistic effects of ultrathin-layer multiple-metallic decoration and gate voltage, which would promote the exploration of novel sensors.

Tailored mesoporous γ-WO3 nanoplates: unraveling their potential for highly sensitive NH3 detection and efficient photocatalysis.

Herein, the monoclinic phase of tungsten oxide (γ-WO3) was successfully obtained after annealing hydrothermally synthesised WO3 powder at 500 °C. As per the result obtained from the N2 adsorption-desorption isotherm, the material has been identified as mesoporous with a specific surface area of 3.71 m2 g-1 from BET (Brunauer-Emmett-Teller) analysis. Moreover, the average pore size (49.52 nm) and volume (0.050 cm3 g-1) were also determined by the BJH (Barrett-Joyner-Halenda) method. FE-SEM (field emission scanning electron microscopy) and HR-TEM (high resolution transmission electron microscopy) have confirmed the formation of nanoplates with an average diameter of approximately 274 nm. Raman spectroscopy has shown peaks at the lower wavenumber region (270 cm-1 and 326 cm-1) and the higher wavenumber region (713 cm-1 and 806 cm-1) for O-W-O bending modes and stretching modes, respectively. The combined effect of relative humidity (RH-11%-RH-95%-RH-11%) and NH3 (150 ppm, 300 ppm, 450 ppm, 600 ppm, 700 ppm, and 800 ppm) was investigated in this reported work. The synthesised γ-WO3 has shown highly responsive behaviour for humidity of 96.5% (RH-11%-95%) and NH3 sensing (under humidity) of 97.4% (RH-11%-95% with 800 ppm NH3). The response and recovery time were calculated as 15 s and 52 s, and 16 s and 54 s for humidity, and NH3 under humidity, respectively. The experimental findings demonstrated that the resistance of the sensor depends on the concentration of NH3 and humidity. Moreover, γ-WO3 has been investigated as a promising catalyst for the dye degradation of methylene blue (MB) with a degradation efficiency of 72.82% and methyl orange (MO) with a degradation efficiency of 53.84% under visible light exposure. This dye degradation occurred within 160 min in the presence of a catalyst under visible light irradiation.

A controllably fabricated polypyrrole nanorods network by doping a tetra-β-carboxylate cobalt phthalocyanine tetrasodium salt for enhanced ammonia sensing at room temperature.

The morphology adjustment and functional doping optimization of polypyrrole (PPy) are of great significance in improving its gas sensing performance. Here, the PPy-0.5TcCoPc nanorods with a uniform dispersed 3-D network were prepared using one-step in situ polymerization using the electrostatic interaction between dopant counterion substituents in tetra-β-carboxylate cobalt phthalocyanine tetrasodium salt (TcCoPcTs) with larger space structure and pyrrole (Py) molecules, in which TcCoPcTs is not only used as a dopant molecule crosslinking PPy chains to obtain a 3-D network, thus improving the conductivity, but also as a sensor accelerator to improve the gas-sensing performance. The resulting PPy-TcCoPc hybrid exhibits superior NH3-sensing properties than PPy and tetra-β-carboxylate cobalt phthalocyanine (TcCoPc) under the same test conditions, especially the PPy-0.5TcCoPc sensor shows ultrafast response/recovery time to 50 ppm NH3 (8.1 s/370.8 s), low detection limit of 8.1 ppb and excellent gas selectivity at room temperature (20 °C). Besides, the PPy-0.5TcCoPc sensor also maintains superior response (49.3% to 50 ppm NH3), humidity resistance and conspicuous stability over 45 days. The excellent NH3-sensing performance of the PPy-0.5TcCoPc hybrid arises from the excellent gas selectivity of TcCoPc, the remarkable response mechanism between PPy and NH3, the high electrical conductivity, abundant active sites and good electron transport ability of the unique 3-D network with large specific surface area. The morphology regulation and functional doping optimization strategy of TcCoPcTs doped PPy broaden the research direction of ideal gas sensor materials.

Modulated wafer-scale WS2 films based on atomic-layer-deposition for various device applications.

Tungsten disulfide (WS2) is promising for potential applications in transistors and gas sensors due to its high mobility and high adsorption of gas molecules onto edge sites. This work comprehensively studied the deposition temperature, growth mechanism, annealing conditions, and Nb doping of WS2 to prepare high-quality wafer-scale N- and P-type WS2 films by atomic layer deposition (ALD). It shows that the deposition and annealing temperature greatly influence the electronic properties and crystallinity of WS2, and insufficient annealing will seriously reduce the switch ratio and on-state current of the field effect transistors (FETs). Besides, the morphologies and carrier types of WS2 films can be controlled by adjusting the processes of ALD. The obtained WS2 films and the films with vertical structures were used to fabricate FETs and gas sensors, respectively. Among them, the Ion/Ioff ratio of N- and P-type WS2 FETs is 105 and 102, respectively, and the response of N- and P-type gas sensors is 14% and 42% under 50 ppm NH3 at room temperature, respectively. We have successfully demonstrated a controllable ALD process to modify the morphology and doping behavior of WS2 films with various device functionalities based on acquisitive characteristics.

A tubular flexible gas sensor fabricated by liquid-borne ultrasound for higher sensitivity and stability

Further enhancement of sensitivity and stability of flexible gas sensors with a low cost will definitely widen their application range. In this work, a novel structure for flexible gas sensors is proposed and developed to significantly enhance the sensing performance, in which a sensing layer is coated on the inner wall of a flexible tube. To coat the sensing layer onto the inner wall, liquid-borne ultrasound is utilized, which not only makes the inner wall coating feasible at room temperature and normal pressure, but also has many green features such as low chemical reagent consumption. To the best of our knowledge, this is the first attempt to apply liquid-borne ultrasound in the coating process for flexible gas sensors. Tubular SnO2-rGO NH3 sensors fabricated by this method, have a measured LDL of 1 ppm, which is lower than the lowest one (5 ppm) of reported planar NH3 sensors with the same sensing material. The sensing response only decreases about 3.6 % for 1 ppm NH3 after 2000 loading-unloading cycles at 40 % strain and 0.5 Hz frequency. Apart from these merits, the inner wall sensing structure can protect the sensing layer from contaminants and touching. Thus, the flexible gas sensors developed in this work have very good mechanical stability.

Synthesis of SnS2/SnO2 nano-heterojunctions with increased reactive sites and charge transfer for ultrasensitive NH3 detection

In this work, the hydrothermally synthesized SnS2 nanosheets were calcined to form SnO2 nanoparticle decorated SnS2 nanosheets. The formed "raisin cake" SnS2/SnO2 complex increases the specific surface area and provides more contact area for gas molecule adsorption. The SnS2/SnO2 nanocomposite has a high sensing response to 50 ppm NH3 (392) and an excellent response/recovery time (6/8 s) to 50 ppm at room temperature. Therefore, SnS2/SnO2 nanocomposite has excellent repeatability, excellent NH3 gas selectivity, and humidity stability. And it is discussed that the reason for the enhanced NH3 sensing mechanism is the synergistic effect of SnS2/SnO2 structures. The existence of heterojunction was proved by XPS. These results demonstrate that the sensing material can effectively detect NH3 gas.

Layered Ti3C2Tx MXene/CuO spindles composites for NH3 detection at room-temperature

Ammonia (NH3) detection is important for human health and environmental protection in our daily life. In this direction, the multilayers Ti3C2Tx MXene/CuO spindles (M-Ti3C2Tx MXene/CuO) composite was synthesized by a simple solvothermal approach for room-temperature (RT) NH3 detection. The CuO spindles as active center components were homogeneously anchored on the surface and the interlayers of the lamelleted Ti3C2Tx MXene. The structure and sensing characteristics of the as-fabricated composites were measured applying an array of analytical technique. The M-Ti3C2Tx MXene/CuO-based sensor indicated excellent sensitivity (46.7% towards 5 ppm NH3) and ideal selectivity. Moreover, the sensor also exhibited the shorter response time (12 s) and recovery time (25 s), brilliant repeatability and great long-term stability. A possible sensing mechanism based on the formation of Ti3C2Tx MXene/CuO heterojunctions was explained in detail in conjunction with density functional theory (DFT) simulations. The designed M-Ti3C2Tx MXene/CuO hybrid material can be considered as a promising candidate for high-performance NH3 detection at room temperature.

In-BTC-derived hexagonal In2O3 nanosheets decorated with Au nanoparticles for enhanced NH3-sensing performance at room temperature

Ammonia (NH3) plays a key role in environmental protection and human health. Therefore, selective detection of NH3 at low temperature is of great significance for environmental monitoring and daily life. In this work, hexagonal In2O3 nanosheets with the thickness of about 35 nm are facilely synthesized from the In-BTC precursors. Then, well-dispersed spherical gold (Au) nanoparticles with diameter of about 10 nm are simultaneously decorated on surface of the In2O3 nanosheets. The sensor based on hexagonal Au-In2O3 nanosheets displayed the highest response (Ra/Rg = 21.42) to 20 ppm NH3 gas at room temperature with the fast response/recovery time of 8/18 s. Meanwhile, the sensor exhibited good repeatability stability and high selectivity towards NH3 among other test gases. The excellent room temperature sensing behavior is ascribed to synergistic effect of nanosheets structure, Au nanoparticles-enhanced surface chemisorption of oxygen species, and the Schottky barrier. The synthesized hexagonal Au-In2O3 nanosheets provide a new candidate for exclusive NH3 detection at room temperature.