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The conversion of CO2 into valuable solar fuels via photocatalysis is a promising strategy for addressing energy shortages and environmental crises. Here, novel In2 O3 @Co2 VO4 hierarchical heterostructures are fabricated by in situ growing Co2 VO4 nanorods onto In2 O3 nanofibers. First-principle calculations and X-ray photoelectron spectroscopy (XPS) measurements reveal the electron transfer between In2 O3 and Co2 VO4 driven by the difference in work functions, thus creating an interfacial electric field and bending the bands at the interfaces. In this case, the photogenerated electrons in In2 O3 transport to Co2 VO4 and recombine with its holes, indicating the formation of In2 O3 @Co2 VO4 S-scheme heterojunctions and resulting in effective separation of charge carriers, as confirmed by in situ irradiation XPS. The unique S-scheme mechanism, along with the enhanced optical absorption and the lower Gibbs free energy change for the production of * CHO, significantly contributes to the efficient CO2 photoreduction into CO and CH4 in the absence of any molecule cocatalyst or scavenger. Density functional theory simulation and in situ diffuse reflectance infrared Fourier transform spectroscopy are employed to elucidate the reaction mechanism in detail.
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With the recently-booming hydrogen (H2) economy by green H2 as the energy carriers and the newly-emerged exhaled diagnosis by human organ-metabolized H2 as a biomarker, H2 sensing is simultaneously required with fast response, low detection limit, and tolerant stability against humidity, switching, and poisoning. Here, reliable H2 sensing has been developed by utilizing indium oxide nanocubes decorated with palladium and gold nanodots (Pd-Au NDs/In2O3 NCBs), which have been synthesized by combined hydrothermal reaction, annealing, and chemical bath deposition. As-prepared Pd-Au NDs/In2O3 NCBs are observed with surface-enriched NDs and nanopores. Beneficially, Pd-Au NDs/In2O3 NCBs show 300 ppb-low detection limit, 5 s-fast response to 500 ppm H2, 75%RH-high humidity tolerance, and 56 days-long stability at 280 °C. Further, Pd-Au NDs/In2O3 NCBs show excellent stability against switching sensing response, and are tolerant to H2S poisoning even being exposed to 10 ppm H2S at 280 °C. Such excellent H2 sensing may be attributed to the synergistic effect of the boosted Pd-Au NDs' spillover effect and interfacial electron transfer, increased adsorption sites over the porous NCBs' surface, and utilized Pd NDs' affinity with H2 and H2S. Practically, Pd-Au NDs/In2O3 NCBs are integrated into the H2 sensing device, which can reliably communicate with a smartphone.
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Wide bandgap semiconductors, particularly In2 O3 :Sn (ITO), are widely used as transparent conductive electrodes in optoelectronic devices. Nevertheless, due to the strohave beenng scattering probability of high-concentration oxygen vacancy (VO ) defects, the mobility of ITO is always lower than 40 cm2 V-1 s-1 . Recently, hydrogen-doped In2 O3 (In2 O3 :H) films have been proven to have high mobility (>100 cm2 V-1 s-1 ), but the origin of this high mobility is still unclear. Herein, a high-resolution electron microscope and theoretical calculations are employed to investigate the atomic-scale mechanisms behind the high carrier mobility in In2 O3 :H films. It is found that VO can cause strong lattice distortion and large carrier scattering probability, resulting in low carrier mobility. Furthermore, hydrogen doping can simultaneously reduce the concentration of VO , which accounts for high carrier mobility. The thermal stability and acid-base corrosion mechanism of the In2 O3 :H film are investigated and found that hydrogen overflows from the film at high temperatures (>250 °C), while acidic or alkaline environments can cause damage to the In2 O3 grains themselves. Overall, this work provides insights into the essential reasons for high carrier mobility in In2 O3 :H and presents a new research approach to the doping and stability mechanisms of transparent conductive oxides.
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In the past several decades, Photoelectrochemical (PEC) sensing still remains a great challenge to design highly-efficient semiconductor photocatalysts via a facile method. It is of much importance to design and synthesize various novel nanostructured sensing materials for further improving the response performance. Herein, we present an In2 O3 /In2 S3 heterostructure obtained by combining microwave assisted hydrothermal method with S-induced phase change, whose energy band and electronic structure could be adjusted by changing the S content. Combining theoretical calculation and spectroscopic techniques, the introduction of sulfur was proved to produce multifunctional interfaces, inducing the change of phase, oxygen vacancies and band gap, which accelerates the separation of photoexcited carriers and reduces their recombination, improving the electronic injection efficiency around the interface of In2 O3 /In2 S3 . As anticipated, an enhanced glucose response performance with a photocurrent of 0.6â mA cm-2 , a linear range of 0.1-1â mM and a detection limit as low as 14.5â µM has been achieved based on the In2 O3 /In2 S3 heterostructure, which is significant superior over its pure In2 O3 and S-doped In2 O3 counterparts. This efficient interfacial strategy may open a new route to manipulate the electrical structure, and energy band structure regulation of sensing material to improve the performance of photoelectrodes for PEC.
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Indium oxide (In2O3) is a promising channel material for thin-film transistors (TFTs). In this work, we develop an atomic layer deposition (ALD) process of using trimethylindium and ozone (O3) to deposit In2O3films and fabricate ultrathin In2O3TFTs. The In2O3TFTs with 4 nm channel thickness show generally good switching characteristics with a highIon/Ioffof 108, a high mobility (µFE) of 16.2cm2V-1s-1and a positive threshold voltage (Vth) of 0.48 V. Although the 4 nm In2O3TFTs exhibit short channel effect, it can be improved by adding an ALD Ga2O3capping layer to afford the bilayer In2O3/Ga2O3channel structure. The afforded In2O3/Ga2O3TFTs exhibit improved immunity to the short channel effect, with good TFT characteristics ofIon/Ioffof 107,µFEof 9.3cm2V-1s-1, and positiveVthof 2.23 V. Overall, the thermal budget of the entire process is only 400 °C, which is suitable for the display and CMOS back-end-of-line-compatible applications.
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A novel photocatalyst In2O3 with loading Ag particles is prepared via a facile one-step annealing method in air atmosphere. The Ag/In2O3 exhibits considerable photoactivity for decomposing sulfisoxazole (SOX), tetracycline hydrochloride (TC), and rhodamine B (RhB) under natural sunlight irradiation, which is much higher than that of pristine In2O3 and Ag species. After natural sunlight irradiation for 100 min, 70.6% of SOX, 65.6% of TC, and 81.9% of RhB are degraded over Ag/In2O3, and their corresponding chemical oxygen demand (COD) removal ratio achieve 95.4%, 38.4%, and 93.6%, respectively. A batch of experiments for degrading SOX with adjusting pollutant solution pH and adding coexisting anions over Ag/In2O3 are carried out to estimate its practical application prospect. Particularly, the as-prepared Ag/In2O3 possesses a superior stability, which exhibits no noticeable deactivation in decomposing SOX after eight cycles' reactions. In addition, the Ag/In2O3 coated on a frosted glass plate, also possesses a superior activity and stability for SOX removal, which solve the possible second pollution of residual powdered catalyst in water. Ag particles on In2O3 working as electron accepter improve charge separation and transfer efficiency, as well as the photo-absorption and organic pollutants affinity, leading to the boosted photoactivity of Ag/In2O3. The photocatalytic mechanism for degrading SOX and degradation process over Ag/In2O3 has been systemically investigated and proposed. This work offers an archetype for the rational design of highly efficient photocatalysts by metal loading.
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Prata , Luz Solar , Prata/química , Poluentes Químicos da Água/química , Catálise , Rodaminas/química , FotóliseRESUMO
A novel ternary heterojunction material In2O3/In2S3/ZnIn2S4 was synthesized, and a photoelectrochemical sensor was fabricated for the non-invasive test of dopamine (DA) in sweat. In2O3 multihollow microtubules were synthesized and then In2S3 was formed on their surface to construct a type-I heterojunction between In2S3 and In2O3. ZnIn2S4 was further introduced to form a Z-scheme heterojunction between In2S3/ZnIn2S4. Under photoexcitation, the photogenerated holes of In2O3 transferred to the valence band of In2S3, superimposed with the holes produced by In2S3, leads to a significantly higher photocatalytic oxidation capacity of In2O3/In2S3/ZnIn2S4 ternary composites than that of In2O3/In2S3. The Z-scheme heterojunction accelerates the transfer of photogenerated electrons accumulated on the type-I heterojunction. In the presence of DA, it is rapidly oxidized into polydopamine (PDA) by In2O3/In2S3, and the benzoquinone groups of PDA compete for the photogenerated electrons to reduce the current in the external circuit, whereby DA determination is achieved. Owing to the combination of type-I and Z-scheme heterojunction, the sensor showed extremely high sensitivity, with a detection limit of 3.94 × 10-12 mol/L. It is one of the most sensitive methods for DA detection reported and has been applied to the determination of DA in human sweat.
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Dopamina , Suor , Humanos , ElétronsRESUMO
In this work, alkali metal Rb-loaded ZnO/In2O3 heterojunctions were synthesized using a combination of hydrothermal and impregnation methods. The morphology and structure of the synthesized samples were characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The enhancement mechanism of the nitrogen dioxide gas sensing performance of the Rb-loaded ZnO/In2O3 heterojunctions was systematically investigated at room temperature using density-functional theory calculations and experimental validation. The experimental tests showed that the Rb-loaded ZnO/In2O3 sensor achieved an excellent response value of 24.2 for 1 ppm NO2, with response and recovery times of 55 and 21 s, respectively. This result is 20 times higher than that of pure ZnO sensors and two times higher than that of ZnO/In2O3 sensors, indicating that the Rb-loaded ZnO/In2O3 sensor has a more pronounced enhancement in performance for NO2. This study not only revealed the mechanism by which Rb loading affects the electronic structure and gas molecule adsorption behavior on the surface of ZnO/In2O3 heterojunctions but also provides theoretical guidance and technical support for the development of high-performance room-temperature NO2 sensors.
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In2O3 has been found a promising application in CO2 hydrogenation to methanol, which is beneficial to the utilization of CO2. The oxygen vacancy (Ov) site is identified as the catalytic active center of this reaction. However, there remains a great challenge to understand the relations between the state of oxygen species in In2O3 and the catalytic performance for CO2 hydrogenation to methanol. In the present work, we compare the properties of multiple In2O3 and Ir-promoted In2O3 (Ir-In2O3) catalysts with different Ir loadings and after being pretreated under different reduction temperatures. The CO2 conversion rate of Ir-In2O3 is more promoted than that of pure In2O3. With only a small amount of Ir loading, the highly dispersed Ir species on In2O3 increase the concentration of Ov sites and enhance the activity. By finely tuning the catalyst structure, Ir-In2O3 with an Ir loading of 0.16 wt.% and pre-reduction treatment under 300°C exhibits the highest methanol yield of 146 mgCH3OH/(gcat·hr). Characterizations of Raman, electron paramagnetic resonance, X-ray photoelectron spectroscopy, CO2-temperature programmed desorption and CO2-pulse adsorption for the catalysts confirm that more Ov sites can be generated under higher reduction temperature, which will induce a facile CO2 adsorption and desorption cycle. Higher performance for methanol production requires an adequate dynamic balance among the surface oxygen atoms and vacancies, which guides us to find more suitable conditions for catalyst pretreatment and reaction.
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Dióxido de Carbono , Metanol , Hidrogenação , Catálise , OxigênioRESUMO
CO2 hydrogenation to methanol has become one of the most promising ways for CO2 utilization, however, the CO2 conversion rate and methanol selectivity of this reaction still need to be improved for industrial application. Here we investigated the structure-activity relationship for CO2 conversion to methanol of In2O3-based catalysts by modulating morphology and decorating Au. Three different Au/In2O3 catalysts were prepared, their activity follow the sequence of Au/In2O3-nanosphere (Au/In2O3-NS) > Au/In2O3-nanoplate (Au/In2O3-NP) > Au/In2O3-hollow microsphere (Au/In2O3-HM). Au/In2O3-NS exhibited the best performance with good CO2 conversion of 12.7%, high methanol selectivity of 59.8%, and large space time yield of 0.32 gCH3OH/(hr·gcat) at 300°C. The high performance of Au/In2O3-NS was considered as the presence of Au. It contributes to the creation of more surface oxygen vacancies, which further promoted the CO2 adsorption and facilitated CO2 activation to form the formate intermediates towards methanol. This work clearly suggests that the activity of In2O3 catalyst can be effective enhanced by structure engineering and Au decorating.
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Dióxido de Carbono , Metanol , Hidrogenação , Adsorção , OxigênioRESUMO
In2 O3 , an n-type semiconducting transparent transition metal oxide, possesses a surface electron accumulation layer (SEAL) resulting from downward surface band bending due to the presence of ubiquitous oxygen vacancies. Upon annealing In2 O3 in ultrahigh vacuum or in the presence of oxygen, the SEAL can be enhanced or depleted, as governed by the resulting density of oxygen vacancies at the surface. In this work, an alternative route to tune the SEAL by adsorption of strong molecular electron donors (specifically here ruthenium pentamethylcyclopentadienyl mesitylene dimer, [RuCp*mes]2 ) and acceptors (here 2,2'-(1,3,4,5,7,8-hexafluoro-2,6-naphthalene-diylidene)bis-propanedinitrile, F6 TCNNQ) is demonstrated. Starting from an electron-depleted In2 O3 surface after annealing in oxygen, the deposition of [RuCp*mes]2 restores the accumulation layer as a result of electron transfer from the donor molecules to In2 O3 , as evidenced by the observation of (partially) filled conduction sub-bands near the Fermi level via angle-resolved photoemission spectroscopy, indicating the formation of a 2D electron gas due to the SEAL. In contrast, when F6 TCNNQ is deposited on a surface annealed without oxygen, the electron accumulation layer vanishes and an upward band bending is generated at the In2 O3 surface due to electron depletion by the acceptor molecules. Hence, further opportunities to expand the application of In2 O3 in electronic devices are revealed.
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Photoelectrochemical-type visible-blind ultraviolet photodetectors (PEC VBUV PDs) have gained ever-growing attention due to their simple fabrication processes, uncomplicated packaging technology, and high sensitivity. However, it is still challenging to achieve high-performance PEC VBUV PDs based on a single material with good spectral selectivity. Here, it is demonstrated that individual ultrathin indium oxide (In2 O3 ) nanosheets (NSs) are suitable for designing high-performance PEC VBUV PDs with high responsivity and UV/visible rejection ratio for the first time. In2 O3 NSs PEC PDs show excellent UV photodetection capability with an ultrahigh photoresponsivity of 172.36 mA W-1 and a high specific detectivity of 4.43 × 1011 Jones under 254 nm irradiation, which originates from the smaller charge transfer resistance (Rct ) at the In2 O3 NSs/electrolyte interface. The light absorption of In2 O3 NSs takes a blueshift due to the quantum confinement effect, granting good spectral selectivity for visible-blind detection. The UV/visible rejection ratio of In2 O3 NSs PEC PDs is 1567, which is 30 times higher than that of In2 O3 nanoparticles (NPs) and exceeds all recently reported PEC VBUV PDs. Moreover, In2 O3 NSs PEC PDs show good stability and good underwater imaging capability. The results verify that ultrathin In2 O3 NSs have potential in underwater optoelectronic devices.
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Direct hydrogenation of CO2 to methanol using green hydrogen has emerged as a promising method for carbon neutrality, but qualifying catalysts represent a grand challenge. In2 O3 /ZrO2 catalyst has been extensively applied in methanol synthesis due to its superior activity; however, the electronic effect by strong oxides-support interactions between In2 O3 and ZrO2 at the In2 O3 /ZrO2 interface is poorly understood. In this work, abundant In2 O3 /ZrO2 heterointerfaces are engineered in a hollow-structured In2 O3 @ZrO2 heterostructure through a facile pyrolysis of a hybrid metal-organic framework precursor MIL-68@UiO-66. Owing to well-defined In2 O3 /ZrO2 heterointerfaces, the resultant In2 O3 @ZrO2 exhibits superior activity and stability toward CO2 hydrogenation to methanol, which can afford a high methanol selectivity of 84.6% at a conversion of 10.4% at 290 °C, and 3.0 MPa with a methanol space-time yield of up to 0.29 gMeOH gcat -1 h-1 . Extensive characterization demonstrates that there is a strong correlation between the strong electronic In2 O3 -ZrO2 interaction and catalytic selectivity. At In2 O3 /ZrO2 heterointerfaces, the electron tends to transfer from ZrO2 to In2 O3 surface, which facilitates H2 dissociation and the hydrogenation of formate (HCOO*) and methoxy (CH3 O*) species to methanol. This study provides an insight into the In2 O3 -based catalysts and offers appealing opportunities for developing heterostructured CO2 hydrogenation catalysts with excellent activity.
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The response of resistive In2O3-x sensing devices was investigated as a function of the NO2 concentration in different operative conditions. Sensing layers are 150 nm thick films manufactured by oxygen-free room temperature magnetron sputtering deposition. This technique allows for a facile and fast manufacturing process, at same time providing advantages in terms of gas sensing performances. The oxygen deficiency during growth provides high densities of oxygen vacancies, both on the surface, where they are favoring NO2 absorption reactions, and in the bulk, where they act as donors. This n-type doping allows for conveniently lowering the thin film resistivity, thus avoiding the sophisticated electronic readout required in the case of very high resistance sensing layers. The semiconductor layer was characterized in terms of morphology, composition and electronic properties. The sensor baseline resistance is in the order of kilohms and exhibits remarkable performances with respect to gas sensitivity. The sensor response to NO2 was studied experimentally both in oxygen-rich and oxygen-free atmospheres for different NO2 concentrations and working temperatures. Experimental tests revealed a response of 32%/ppm at 10 ppm NO2 and response times of approximately 2 min at an optimal working temperature of 200 °C. The obtained performance is in line with the requirements of a realistic application scenario, such as in plant condition monitoring.
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Recent research on the use of physical mixtures In2O3-ZrO2 has raised interesting questions as to how their combination enhances catalytic activity and selectivity. Specifically, the relationship between oxygen diffusion and defect formation and the epitaxial tension in the mixture should be further investigated. In this study, we aim to clarify some of these relationships through a molecular dynamics approach. Various potentials for the two oxides are compared and selected to describe the physical mixture of In2O3 and ZrO2. Different configurations of each single crystal and their physical mixture are simulated, and oxygen defect formation and diffusion are measured and compared. Significant oxygen defect formation is found in both crystals. In2O3 seems to be stabilized by the mixture, while ZrO2 is destabilized. Similar results were found for the ZrO2 doping with In and ln2O3 doping with Zr. The results explain the high activity and selectivity catalyst activity of the mixture for the production of isobutylene from ethanol.
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Simulação de Dinâmica Molecular , Zircônio , Zircônio/química , Óxidos/química , Catálise , OxigênioRESUMO
The efficient degradation of organic effluent is always desirable when using advanced photocatalysts with enhanced activity under visible light. Nickel-doped indium oxide (Ni-In2O3) is synthesized via a hydrothermal route as well as its composites with reduced graphene oxide (rGO). Facile synthesis and composite formation methods lead to a well-defined morphology of fabricated nanocomposite at low temperatures. The bandgap energy of indium oxide lies in the range of 3.00-4.30 eV. Its high light absorption capacity, high stability, and non-toxicity make it a choice as a photocatalyst that is active under visible light. The transition metal Ni-doping changes the indium oxide's chemical, optical, and physicochemical properties. The Ni-In2O3 and rGO composites improved the charge transport and reduced the charge recombination. The phase analysis of the developed photocatalysts was performed using X-ray diffraction (XRD), and the morphological and structural properties were observed using advanced microscopic techniques (SEM and TEM), while UV-vis and FTIR spectroscopic techniques were used to confirm the structure and optical and chemical properties. The electrochemical properties of the photocatalysts were investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS), and the charge-transfer properties of the obtained photocatalysts and the mechanism of the photocatalytic degradation mechanism of methylene blue, a common dye used in the dyeing industry, were determined.
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Poluentes Ambientais , Nanopartículas , Águas Residuárias , Óxidos/química , Luz , Nanopartículas/químicaRESUMO
The construction of a surface-frustrated Lewis pairs (SFLPs) structure is expected to break the single electronic state restriction of catalytic centers of P-region element materials, due to the existence of acid-base and basic active canters without mutual quenching in the SFLPs system. Herein, we have constructed eight possible SFLPS structures on the In2O3 (110) surface by doping non-metallic elements and investigated their performance as electrocatalytic nitrogen reduction catalysts using density functional theory (DFT) calculations. The results show that P atom doping (P@In2O3) can effectively construct the structure of SFLPs, and the doped P atom and In atom near the vacancy act as Lewis base and acid, respectively. The P@In2O3 catalyst can effectively activate N2 molecules through the enzymatic mechanism with a limiting potential of -0.28 eV and can effectively suppress the hydrogen evolution reaction (HER). Electronic structure analysis also confirmed that the SFLPs site can efficiently capture N2 molecules and activate N≡N bonds through a unique "donation-acceptance" mechanism.
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The incorporation of graphene with metal oxide has been widely explored in various fields, including energy storage devices, optical applications, biomedical applications, and water remediation. This research aimed to assess the impact of reduced graphene oxide (RGO) doping on the photocatalytic and anticancer properties of In2O3 nanoparticles. Pure and In2O3/RGO nanocomposites were effectively synthesized using the single-step microwave hydrothermal process. XRD, TEM, SEM, EDX, XPS, Raman, UV-Vis, and PL spectroscopy were carefully utilized to characterize the prepared samples. XRD data showed that synthesized In2O3 nanoparticles had high crystallinity with a decreased crystal size after RGO doping. TEM and SEM images revealed that the In2O3 NPs were spherical and uniformly embedded onto the surface of RGO sheets. Elemental analysis of In2O3/RGO NC confirmed the presence of In, O, and C without impurities. Raman analysis indicated the successful fabrication of In2O3 onto the RGO surface. Uv-Vis analysis showed that the band gap energy was changed with RGO addition. Raman spectra confirmed that In2O3 nanoparticles were successfully anchored onto the RGO sheet. PL results indicated that the prepared In2O3/RGO NCs can be applied to enhance photocatalytic activity and biomedical applications. In the degradation experiment, In2O3/RGO NCs exhibited superior photocatalytic activity compared to that of pure In2O3. The degradation efficiency of In2O3/RGO NCs for MB dye was up to 90%. Biological data revealed that the cytotoxicity effect of In2O3/RGO NCs was higher than In2O3 NPs in human colorectal (HCT116) and liver (HepG2) cancer cells. Importantly, the In2O3/RGO NCs exhibited better biocompatibility against human normal peripheral blood mononuclear cells (PBMCs). All the results suggest that RGO addition improves the photocatalytic and anticancer activity of In2O3 NPs. This study highlights the potential of In2O3/RGO NCs as an efficient photocatalyst and therapeutic material for water remediation and biomedicine.
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Grafite , Nanocompostos , Humanos , Grafite/farmacologia , Grafite/química , Azul de Metileno/farmacologia , Azul de Metileno/química , Leucócitos Mononucleares , Micro-Ondas , Água , Nanocompostos/químicaRESUMO
Ternary Pd-In2 O3 /ZrO2 catalysts exhibit technological potential for CO2 -based methanol synthesis, but developing scalable systems and comprehending complex dynamic behaviors of the active phase, promoter, and carrier are key for achieving high productivity. Here, we show that the structure of Pd-In2 O3 /ZrO2 systems prepared by wet impregnation evolves under CO2 hydrogenation conditions into a selective and stable architecture, independent of the order of addition of Pd and In phases on the zirconia carrier. Detailed operando characterization and simulations reveal a rapid restructuring driven by the metal-metal oxide interaction energetics. The proximity of InPdx alloy particles decorated by InOx layers in the resulting architecture prevents performance losses associated with Pd sintering. The findings highlight the crucial role of reaction-induced restructuring in complex CO2 hydrogenation catalysts and offer insights into the optimal integration of acid-base and redox functions for practical implementation.
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With the demanding detection of unique toxic gas, semiconductor gas sensors have attracted tremendous attention due to their intriguing features, such as, high sensitivity, online detection, portability, ease of use, and low cost. Triethylamine, a typical gas of volatile organic compounds, is an important raw material for industrial development, but it is also a hazard to human health. This review presents a concise compilation of the advances in triethylamine detection based on chemiresistive sensors. Specifically, the testing system and sensing parameters are described in detail. Besides, the sensing mechanism with characterizing tactics is analyzed. The research status based on various chemiresistive sensors is also surveyed. Finally, the conclusion and challenges, as well as some perspectives toward this area, are presented.