Ppm NO2 Research Articles

Differential detection of NH3 and NO2 by polymer non-covalently encapsulated semiconducting single-walled carbon nanotubes

Semiconductor single-walled carbon nanotubes (sc-SWCNTs) exhibit exceptional optoelectronic properties and possess a substantial specific surface area, rendering them highly promising materials for the development of gas sensors with increasing the sensitivity and portability. In this study, we synthesized polymer bearing two Schiff base side chains (PF2L) via the Suzuki coupling reaction with enhanced polymer solubility. The sc-SWCNTs were selectively sorted using PF2L from commercially available SWCNTs to prepare PF2L/sc-SWCNTs composites. The incorporation of side chains enhanced the π-π interactions within the polymers and facilitated the interactions between the polymers and SWCNTs, thereby promoting superior dispersion of sc-SWCNTs. The PF2L/sc-SWCNTs-based sensors were fabricated using the drop-coating method, and their gas sensing performance was evaluated for gases with distinct properties (reducing: NH3 and oxidizing: NO2). The sensor exhibits a response of 2.415 % and 14.85 % for 1 ppm NH3 vapor and 1 ppm NO2, respectively. The sensor shows response and recovery times of 50 s and 220 s, respectively, for the detection of 1 ppm NH3 vapor, while it demonstrated response and recovery times of 59 s and 733 s for the detection of 1 ppm NO2. Subsequently, we developed an LED-based detection device for the selective discrimination of NH3 vapor and NO2, thereby offering valuable insights into the potential practical applications of a single material for dual gas sensing.

Impact of gas flowrate on performance of chemiresistive NO2 sensors

This paper investigates in-depth the practical implications and the underlying mechanism of the effect of gas flowrate on the sensing performances of chemiresistive sensors. Three different types of 2D sensing layers were chosen for this study − metal oxide (ZnO, synthesized using hydrothermal method), organic polymer (tetrazine, synthesized using modified Pinner method), and transition metal dichalcogenide (WS2, synthesized using liquid exfoliation technique). The 2D morphologies of all the materials were confirmed using a field emission scanning electron microscope. These materials have different crystallographic structures, bandgaps, and functional groups. Yet, the response of all of them for 2–10 ppm NO2 was found to increase with increasing total flowrates when tested at 100, 500, and 1000 sccm. The response of ZnO varied from 6 to 46 %, 93 to 521 %, and 117 to 1416 %, while that of 2D tetrazine was found to vary from − 5.3 to − 13.9 %, −8.1 to − 26.5 %, and − 8.9 to − 34.2 %, and for WS2, the response ranged from 0 %, −0.8 to − 5.2 %, and − 2 to − 12.2 % for 2 – 10 ppm NO2 at 100, 500, and 1000 sccm flowrates, respectively. The response times and the recovery times of all the materials, too, exhibited the effect of gas flowrate.

Low ppm NO2 detection through advanced ultrasensitive copper oxide gas sensor

The imperative development of a cutting-edge environmental gas sensor is essential to proficiently monitor and detect hazardous gases, ensuring comprehensive safety and awareness. Nanostructures developed from metal oxides are emerging as promising candidates for achieving superior performance in gas sensors. NO2 is one of the toxic gases that affects people as well as the environment so its detection is crucial. The present study investigates the gas sensing capability of copper oxide-based sensor for 5 ppm of NO2 gas at 100 °C. The sensing material was synthesized using a facile precipitation method and characterized by XRD, FE-SEM, UV–visible spectroscopy, photoluminescence spectroscopy, XPS and BET techniques. The developed material shows a response equal to 67.1% at optimal temperature towards 5 ppm NO2 gas. The sensor demonstrated an impressive detection limit of 300 ppb, along with a commendable percentage response of 5.2%. Under optimized conditions, the synthesized material demonstrated its high selectivity, as evidenced by the highest percentage response recorded for NO2 gas among NO2, NH3, CO, CO2 and H2S.

Biotemplate synthesis of graphitic carbon-doped ZnO tube bundles rich in oxygen vacancies for dual-sensing of NO2/H2S at different temperatures

How to fabricate one chemiresistive sensor for highly dual-selective detection of hazardous NO2 and H2S gases is a challenge owing to the fact that the great majority of gas sensors were designed to monitor only a given harmful gas. For the aim of portable practicality and internet of things, based on green and sustainable concept, natural poplar branches were utilized as template and simply soaked in zinc nitrate solution. Subsequently, the immersed biotemplates underwent air calcination to controllably reproduce two biomorphic ZnO-based materials. Among, the hierarchical tubes (GC/ZnO) prepared by calcination at 450 °C are interconnected by 5.68 wt% in-situ graphitic carbon (GC) and uniform nanoparticles, which possess small mesopores, large specific surface area and massive oxygen vacancies. Such distinctive microstructure not only facilitates rapid gas diffusion into sensing layer and modulates the state of adsorbed oxygen species, but also exposes more active sensing units and promotes surface chemical reactions, thus realizing a portable gas sensor for highly sensing and dual-selective detection of NO2 and H2S. At lower 92 °C or 133 °C, the GC/ZnO sensor exhibits response values of 203 and 65.5 for 10 ppm NO2 or H2S gases, respectively. Meanwhile, it possesses reversible response-recovery, low detection limit, good moisture tolerance and stability during 60 days. In addition, the temperature-controlled dual-response mechanism is also analyzed.

Polar tri-glycol side chain for enhanced detection to low concentrations of NO2 at room temperature

It has been widely studied the impact of polar side-chain on the modification of conjugated polymers and the thermoelectric properties of composites, but relatively little research has been carried out in the gas sensing field. In this study, two π-conjugated polymers PFTC8 and PFTO with similar backbone but different polar-side chains were synthesized. The separation efficiency of the polymers for semiconducting single-walled (sc-SWCNTs) and the NO2 sensing performance were also investigated. It was found that the introduction of the polar side chains not only enhanced the sorting efficiency of the polymer for sc-SWCNTs (greater than 99 %), but also further improved the responsive performance of the sensor to NO2. After the introduction of polar side chains, the response value of the composite PFTO@sc-SWCNTs towards 1 ppm NO2 was achieved to be 21.7 % at room temperature. Furthermore, the response time (Tres = 23 s) and recovery time (Trec = 134 s) of PFTO@sc-SWCNTs to 1 ppm NO2 were also greatly shortened. The strategy for improving the NO2 gas response performance by introducing polar side chains is proposed.

Improved NO2 Sensing Performance of Ternary Nanocomposites Based on Au-doped Co3O4/CuO

To enhance the poor sensing capabilities of traditional p-type metal oxide semiconductor sensors, a novel gas sensor was designed with Co3O4/CuO heterostructure modified by glutathione (GSH)-reduced gold (Au), which was characterized by different analyses. The experiments showed that the 0.5[Formula: see text]wt.% Au–Co3O4/CuO gas sensor exhibited excellent sensing performance with a response value of up to 28.3 for 3[Formula: see text]ppm NO2 at a relatively low operating temperature ([Formula: see text]C). Besides, it demonstrated a linear relationship between detection concentration and response value, displayed good selectivity for NO2, showcased stability and exhibited repeatability. Moreover, the sensor revealed the ability to resist humidity at the optimal temperature. Finally, we proposed a gas sensing mechanism to explain the enhanced NO2 detection performance of the sensor, attributed to the heterojunction structure between Co3O4/CuO and the catalytic properties of Au. This led to an increase in adsorbed oxygen, as confirmed by XPS characterization. Therefore, the 0.5[Formula: see text]wt.% Au–Co3O4/CuO ternary nanocomposite gas sensor is deemed to be a highly effective sensing material that can be utilized to detect NO2 gas in real-life applications.

Ultrasensitive and highly selective NO2 gas sensing of porous MXene nanoribbon assemblies

Nitrogen dioxide (NO2), a potential source for acid rain and photochemical smog, is known to harm human health, plant growth and crop yield, and the environment. Therefore, designing a room temperature operable NO2 gas sensor with exceptional sensitivity and selectivity is extremely important. Herein, we report that Ti3C2Tx MXene (Tx = –OH, –O, –F, etc.) nanoribbons containing inbuilt anatase TiO2 on their surfaces achieve highly sensitive detection of NO2 gas at room temperature with negligible cross-responses to other gas analytes. The MXene nanoribbons' ability to form porous gas sensor film facilitates the efficient diffusion of gas molecules and the sufficient utilization of surface-active sites, leading to a high response of −87.5 % to 50 ppm NO2 gas exposure with a response time of 9.2 s at room temperature. Signifying the low concentration NO2 detection abilities, MXene nanoribbons displayed a response of −4.4 % towards 500 ppb NO2 exposure. MXene nanoribbons' NO2 gas sensing ability is carrier gas dependent and declines monotonically as operating temperature increases. In addition, the performance comparison experiments conducted at 50 ppm NO2 gas exposure suggest that the MXene nanoribbons' response is 14.3, 1.6, and 45.3 times higher than the responses of multilayer MXene, MXene-TiO2 nanoplate, and MXene-TiO2 nanoparticle structures, respectively. The explicit selectivity and high sensitivity of MXene nanoribbons toward NO2 gas are expected to provide exciting opportunities for personal safety and environmental monitoring.

The Nephroprotective Effect of Nitric Oxide during Extracorporeal Circulation: An Experimental Study.

This study aims to determine the effectiveness of administering 80 ppm nitric oxide in reducing kidney injury, mitochondrial dysfunction and regulated cell death in kidneys during experimental perfusion. Twenty-four sheep were randomized into four groups: two groups received 80 ppm NO conditioning with 90 min of cardiopulmonary bypass (CPB + NO) or 90 min of CPB and hypothermic circulatory arrest (CPB + CA + NO), while two groups received sham protocols (CPB and CPB + CA). Kidney injury was assessed using laboratory (neutrophil gelatinase-associated lipocalin, an acute kidney injury biomarker) and morphological methods (morphometric histological changes in kidney biopsy specimens). A kidney biopsy was performed 60 min after weaning from mechanical perfusion. NO did not increase the concentrations of inhaled NO2 and methemoglobin significantly. The NO-conditioning groups showed less severe kidney injury and mitochondrial dysfunction, with statistical significance in the CPB + NO group and reduced tumor necrosis factor-α expression as a trigger of apoptosis and necroptosis in renal tissue in the CPB + CA + NO group compared to the CPB + CA group. The severity of mitochondrial dysfunction in renal tissue was insignificantly lower in the NO-conditioning groups. We conclude that NO administration is safe and effective at reducing kidney injury, mitochondrial dysfunction and regulated cell death in kidneys during experimental CPB.

Functional F-doped SnSx modified ZnOHF heterojunctions for efficient NO2 gas sensing

Constructing heterojunctions in semiconductor-based sensors is a vital method of modulating electronic structures and designing high-performance sensors for toxic gas detection. In this study, F-doped SnSx (F-SnSx) decorated ZnOHF composites were acquired via a two-step solvothermal method. The experimental results confirmed the establishment of heterojunctions between ZnOHF and F-SnSx. The optimized F-SnSx decorated ZnOHF snowflake-like nanoflowers-based NO2 sensors exhibited incomparable selectivity along with supreme sensitivity (S = 137–10 ppm NO2 at 200 ℃), rapid responding/recovering speed (34 s/6 s) and low detection limit (50 ppb). NO2 sensing mechanism and the influence of humidity interference on NO2 sensing performances were fully discussed. This work not only evidences the great potential of F-SnSx/ZnOHF snowflake-like nanoflowers for NO2 recognitions but also paves a feasible routine for advancing NO2 sensing performances by electronic structure regulations.

Bilayer Porous Electrocatalysts for Stable and Selective Electrochemical Reduction of CO2 to Formate in the Presence of Flue Gas Containing NO and SO2.

The development of stable and selective electrocatalysts for converting CO2 to value-added chemicals or fuels has gained much interest in terms of their potential to mitigate anthropogenic carbon emissions. Most of the electrocatalysts are tested under pure CO2; however, industrial outlet flue gas contains numerous impurities, such as NO and SO2, which poison the electrocatalysts and alter the product selectivity. Developing electrocatalysts that are resistant to such impurities is essential for commercial implementation. Herein, we prepared bilayer porous electrocatalysts, namely, Sn, Bi, and In, on porous Cu foam mesh (Sn/Cu-f, Bi/Cu-f, and In/Cu-f) by a two-step electrodeposition process and employed these electrodes for the electrochemical reduction of CO2 to formate. It was observed that the bilayer porous electrocatalysts exhibited high CO2 reduction activity compared to catalysts coated on a Cu mesh. Among bilayer porous electrocatalysts, Sn/Cu-f and Bi/Cu-f electrocatalysts showed more than 80% faradaic efficiency (FE) toward formate production, with a formate partial current density of around -16 and -10.4 mA cm-2, respectively, at -1.02 V vs RHE. In/Cu-f electrocatalyst showed nearly 40% formate FE with formate partial current density of -15 mA cm-2 at -1.22 V vs RHE. We investigated the effect of NO and SO2 impurities (500 ppm of NO, 800 ppm of SO2, and 500 ppm of NO + 800 ppm of SO2) on these electrocatalysts' selectivity and stability toward formate. It was observed that the Bi/Cu-f electrocatalyst showed 50 h stability with 80 ± 5% formate FE, and Sn/Cu-f showed 18 h stability with above 80 ± 5% efficiency in the presence of NO and SO2 mixed with CO2. Furthermore, we studied the effect of CO2 concentration with Sn/Cu-f and Bi/Cu-f catalysts in the range of 15-100% CO2, for which formate FEs of 45-80% were observed.

Effects of Zn loading on ZnxCo1−xCo2O4 spinel catalysts for low-temperature catalytic decomposition of N2O in the presence of inhibitors

The recent advancement of NH3-based fuel demands the development of catalysts that can decompose N2O at low temperatures and are stable against various inhibitors. Zn-doped cobalt spinel (ZnxCo1−xCo2O4) catalysts have demonstrated superior activity for N2O decomposition at low temperatures. However, their optimization and deactivation mechanisms with respect to Zn loading when inhibitors are present require further investigation. Herein, we reviewed the effects of Zn loading on catalysts at low temperatures without or with the presence of inhibitors (3 vol% O2, 6 vol% H2O, 200 ppm NO). The results showed that adding an appropriate amount of Zn into Co3O4 spinel catalysts improves their N2O decomposition activity. The Zn-induced enhancement of the catalysts’ redox properties, and reducibility was the underlying mechanism behind the activity promotion. The presence of structural defects created through the addition of Zn enhanced the catalyst’s resistance to O2. The deactivation by H2O and NO upon the addition of Zn could be correlated with the reduced availability of surface Co species and Co2+ as adsorption-active sites and the stronger bond of Co with –NO, respectively. This study underscores the importance of controlling the Zn loading as a bulk redox promoter in ZnxCo1−xCo2O4 spinel catalysts for practical applications.

NO2 sensing characteristics by α-Fe2O3 nanorod arrays with atomic layer deposited amorphous Al2O3 overlayer

We have grown α-Fe2O3 nanorods by solution processing followed by the deposition of Al2O3 overlayer using atomic layer deposition. Al2O3 layer was deposited for two different thicknesses 4 nm and 8 nm and a post-deposition annealing at 550 °C for 2 h in air atmosphere was performed. Crystallinity analysis through x-ray diffraction (XRD) reveals that the α-Fe2O3 nanorods crystallized into rhombohedral structure, whereas the outer Al2O3 layers remained largely amorphous. Interestingly, the interface showed signs of AlFexOy formation as observed through high-resolution transmission electron microscopy images. Gas sensing characteristics were studied using NO2 with 10, 50, and 100 ppm concentrations at operating temperatures of 30 °C, 100 °C, 150 °C and 190 °C. The room temperature sensitivity values obtained in response to 10 ppm NO2 were 31%, which surpassed the previously reported values. A higher concentration of surface adsorbed oxygen on the Al2O3 overlayer, as revealed by the x-ray photoelectron spectroscopy (XPS) analysis, led to enhanced NO2 sensing at room temperature. A lower activation energy (0.29 eV) of barrier to charge transport for Al2O3 coated α-Fe2O3 nanorods compared to that of bare nanorods (0.45 eV), as calculated from the temperature dependent I-V measurements, supported observation of higher sensitivity at room temperature.

Preparation of SnS2/MoS2 with p–n heterojunction for NO2 sensing

Conventional metal sulfide (SnS2) gas-sensitive sensing materials still have insufficient surface area and slow response/recovery times. To increase its gas-sensing performance, MoS2 nanoflower was produced hydrothermally and mechanically combined with SnS2 nanoplate. Extensive characterization results show that MoS2 was effectively integrated into SnS2. Four different concentrations of SnS2–MoS2 composites were evaluated for their NO2 gas sensitization capabilities. Among them, SnS2–15% MoS2 at 170 °C demonstrated the greatest response values to NO2, 7.3 for 1 ppm NO2, which is about three times greater than the SnS2 sensor at 170 °C (2.58). The creation of pn junctions following compositing with SnS2 was determined to be the primary reason for the composite’s faster recovery time, while the heterojunction allowed for the rapid separation of hole–electron pairs. Because the MoS2 surface has multiple vacancy defects, the adsorption energy of these vacancies is significantly higher than that of other places, resulting in increased NO2 adsorption. Furthermore, MoS2 can serve as active adsorption sites for SnS2 micrometer sheets during gas sensing. This study may help to build new NO2 gas sensors.

ZnIn2S4 Nanosheets for Efficient NO2 Detection at Room Temperature: Insights into the Role of Sulfur Vacancies.

Engineering atomic vacancies in metal sulfide semiconductors allows for the efficient tuning of their electronic and chemical properties. In this work, we synthesized hollow tubular structures constructed by bimetallic ZnIn2S4 using a metal-organic framework (MOF) as the template. We found that the sulfur vacancies in ZnIn2S4 enabled extremely fast NO2 detection with high response at room temperature (RT), and the material with high sulfur vacancy content delivers a 2 times higher response to 10 ppm NO2 than the device with low sulfur vacancy content. To unveil the crucial role played by sulfur vacancies, DFT calculations were conducted to reveal that sulfur vacancies greatly enhance the interaction and electron transfer between ZnIn2S4 and NO2. This study will provide hints for the engineering of bimetallic sulfide materials for low-power gas sensors at RT.

High-performance NO2 gas sensor enabled by Fe, N co-doped GQDs modification and pulse-driven temperature modulation

Nitrogen dioxide (NO2) is a typical reactive nitrogen species harmful to health and the environment. However, NO2 sensors still suffer from low sensitivity and poor response/recovery rates. Herein, 3D In2O3 assembled by stacked nanosheets were prepared and modified with N element-doped GQDs (N-GQDs) and Fe, N co-doped GQDs (Fe,N-GQDs), respectively. The results of NO2-sensing performance indicated that the optimal sample (0.3 wt% Fe,N-GQDs/In2O3) showed a high response of 414.5 to 1 ppm NO2 and could detect as low as 10 ppb at 50℃, which was 1.3 and 4.0 times higher than that of 0.3 wt% N-GQDs/In2O3 and In2O3, respectively. The gas-sensing kinetics were analyzed by establishing gas adsorption/desorption isotherms. The enhanced NO2 sensing properties of 0.3 wt% Fe,N-GQDs/In2O3 were mainly due to the enhanced active site accessibility of stacked nanosheets with open layer spaces, the heterointerface between Fe,N-GQDs and In2O3, and electrical modulation of Fe,N-GQDs. Additionally, A pulse-driving circuit was designed for a pulse temperature modulation (PTM) strategy to further boost NO2 detection. The sensor response is further enhanced by 1.7 times, and the response/recovery time is reduced by 42.5 %/60.1 %. The NO2 concentration in vehicle exhaust was determined using PTM mode with good spike recoveries. It validated the reliability of the sensor for the quantitative detection of NO2 in the real environment. This work provides insights into sensor design and has the potential to contribute to the development of novel sensing platforms for other gas pollutants.

Low-temperature NO2 sensor based on γ-In2Se3/In2O3 nanoflower heterojunction

The γ-In2Se3/In2O3 nanoflower-like heterojunctions were synthesized by solvothermal treatment followed by thermal oxidation in Air. The nanoflower-like γ-In2Se3/In2O3-based chemiresistive-type sensor showed a significantly enhanced response to NO2 at an operating temperature of 170°C. The sensor achieves a response of 2.69–0.2 ppm NO2 at 170°C. The sensor exhibits remarkable selectivity to several possible interferents such as carbon monoxide, ammonia, formaldehyde, acetone, methanol, and toluene, and good stability at 170°C. The nanoflower structure increases the specific surface area and introduces more active sites, which improves the sensitivity of the sensor to NO2. The heterojunction formed between γ-In2Se3 and In2O3 improves the charge carrier transfer between NO2 gas molecules and sensing materials, thereby increasing the response of the sensor to NO2. Density functional theory was used to elucidate this sensing mechanism, and it was found that improved sensing performance is mainly due to heterojunction formation, which increases the adsorption energy of nitrogen dioxide molecules on a sensing material surface and facilitates charge transfer between molecules.

Impact of oxygen vacancies on enhanced NO2 gas sensing performance of lithium doped Co:ZnO thin films

This article explored the influence of lithium on cobalt-doped ZnO thin films fabricated via the sol–gel spin coating technique for NO2 gas sensing applications. The abundance of oxygen vacancies in ZnO can be proven by scanning electron microscopy, four-probe Hall measurements, photoluminescence spectroscopy, UV-visible spectroscopy, and x-ray photoelectron spectroscopy. The presence of lithium plays a crucial role in generating more oxygen vacancies in Co-doped ZnO was discussed. Among the fabricated samples, (Li-Co) co-doped ZnO exhibits better sensitivity (2940.17%), selectivity, repeatability, and stability (after 90 days) toward 75 ppm NO2 gas.

Amorphous RhOx decorated black indium oxide for rapid and flexible NO2 detection at room temperature

This paper focuses on the preparation and characterization of a composite material made from rhodium oxide amorphous-decorated black indium oxide (RhOx/B-In2O3) for use in MEMS gas sensors. The sensors were utilized for the detection of NO2 gas at room temperature, and the results demonstrate that the RhOx/B-In2O3 sensor exhibits excellent gas selectivity, high response, and extremely short response/recovery times (8 s/17 s) to 5 ppm NO2 gas at room temperature. Additionally, a flexible NO2 gas sensor based on the optimized RhOx/B-In2O3 composite was fabricated to expand its application. One of the unique aspects of the RhOx/B-In2O3 material is the existence of defects, which allows for greater adsorption of NO2 gas. This feature contributes to the increased gas selectivity seen in the B-In2O3 material as compared with common In2O3. The chemical sensitization and electron-rich properties of amorphous RhOx further enhance the gas-sensing performance of the material by reducing the reaction activation energy and increasing surface-adsorbed oxygen. Overall, the results demonstrate the potential of the RhOx/B-In2O3 composite material for use in advanced gas-sensing technologies.

Microwave-Solvothermal Synthesis of Mesoporous CeO2/CNCs Nanocomposite for Enhanced Room Temperature NO2 Detection.

Nitrogen dioxide (NO2) gas sensors are pivotal in upholding environmental integrity and human health, necessitating heightened sensitivity and exceptional selectivity. Despite the prevalent use of metal oxide semiconductors (MOSs) for NO2 detection, extant solutions exhibit shortcomings in meeting practical application criteria, specifically in response, selectivity, and operational temperatures. Here, we successfully employed a facile microwave-solvothermal method to synthesize a mesoporous CeO2/CNCs nanocomposite. This methodology entails the rapid and comprehensive dispersion of CeO2 nanoparticles onto helical carbon nanocoils (CNCs), resulting in augmented electronic conductivity and an abundance of active sites within the composite. Consequently, the gas-sensing sensitivity of the nanocomposite at room temperature experienced a notable enhancement. Moreover, the presence of cerium oxide and the conversion of Ce3+ and Ce4+ ions facilitated the generation of oxygen vacancies in the composites, thereby further amplifying the sensing performance. Experimental outcomes demonstrate that the nanocomposite exhibited an approximate 9-fold increase in response to 50 ppm NO2 in comparison to pure CNCs at room temperature. Additionally, the CeO2/CNCs sensor displayed remarkable selectivity towards NO2 when exposed to gases such as NH3, CO, SO2, CO2, and C2H5OH. This straightforward microwave-solvothermal method presents an appealing strategy for the research and development of intelligent sensors based on CNCs nanomaterials.

Enhanced sensitivity of zero‐bias‐operated MXene chemiresistive sensor via lignin hybridization

AbstractAs global urbanization intensifies, there is an increasing need for highly sensitive and accurate environmental monitoring devices that can meet the demands of specific gas sensing applications with low power consumption. This study focuses on enhancing the sensitivity of MXene‐based chemiresistive sensors for detecting CO2(g) and NO2(g) under zero‐bias operation. This study shows that lignin hybridization effectively improves the sensitivity of a Ti3C2Tx MXene‐based chemiresistive sensor; under zero‐bias operation, lignin hybridization increases the sensitivity to 15 ppm NO2(g) and CO2(g) by 157.38% and 297.95%, respectively. When deposited on a flexible substrate, the MXene/lignin flexible sensor shows a similar response and sensitivity to 15 ppm NO2(g) and CO2(g) under 38° curvature compared to the planar sensor. Consequently, the MXene/lignin hybrid sensor is attractive for room temperature and zero‐bias NO2(g) and CO2(g) detection. The MXene/lignin flexible sensor serves as a model system for advanced solid‐state sensory platforms suitable for curved structures.image