Pd-modified SmFeO_(3)with hollow tubular structure under light shows extremely high acetone gas sensitivity

Currently,SmFeO_(3)-based sensors are an effective platform for detecting acetone gas.However,they require high operating temperatures,which increases energy consumption and safety hazards,and their response is low when the gas concentration is at 10^(-9)(PPB),which cannot meet the requirements of using exhaled breath to pre-diagnose diabetes.Herein,Pd-SmFeO_(3)hollow nanotubes with an extremely high specific surface area and porosity were synthesized by electrospinning.After Pd doping,the specific surface area improved by more than two times,and the acetone response improved by more than three times.In addition,the response further improved by more than 1.5 times,and the optimum operating temperature reduced by 100℃under light irradiation.Moreover,the relative humidity adaptability,long-term stability,and selectivity of the material were significantly improved after Pd doping or light irradiation.Finally,the acetone concentration in a person’s exhaled breath was detected by a Pd-SmFeO_(3)-based gas sensor,and the error was less than 10%compared to that obtained by gas chromatography-mass spectrometry method.

Controllable synthesis of highly crystallized mesoporous TiO2/WO3 heterojunctions for acetone gas sensing

Mesoporous semiconducting metal oxides(SMOs)heterojunctions are appealing sensors for gas detecting.However,due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction between high crystallinity and high surface area,the synthesis of mesoporous SMOs heterojunctions with highly o rdered mesostructures,highly crystallized frameworks,and high surface area remains a huge challenge.In this work,we develop a novel"acid-base pair"adjusted solvent evaporation induced self-assembly(EISA)strategy to prepare highly crystallized ordered mesoporous TiO2/WO3(OM-TiO2/WO3)heterojunctions.The WCl6 and titanium isopropoxide(TIPO)are used as the precursors,respectively,which function as the"acid-base pair",enabling the coassembly with the structure directing agent(PEO-b-PS)into highly ordered meso structures.In addition,PEO-b-PS can be converted to rigid carbon which can protect the meso structures from collapse during the crystallization process.The resultant OM-TiO2/WO3 heterojunctions possess primitive cubic mesostructures,large pore size(~21.1 nm),highly crystalline frameworks and surface area(~98 m2/g).As a sensor for acetone,the obtained OM-TiO2/WO3 show excellent re sponse/recovery perfo rmance(3 s/5 s),good linear dependence,repeatability,selectivity,and long-term stability(35 days).

SnO-SnO_(2) modified two-dimensional MXene Ti3C2Tx for acetone gas sensor working at room temperature

Acetone,as widely used reagents in industry and laboratories,are extremely harmful to the human.So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential.Herein,the nanocomposite combining SnO-SnO_(2)(p-n junction)and Ti_(3)C_(2)T_(x) MXene was successfully synthesized by a one-step hydrothermal method.Because of the existence of a small amount of oxygen during the hydrothermal conditions,part of the p-type SnO was oxidized to n-type SnO_(2),forming in-situ p-n junctions on the surface of Sn O.The hamburger-like SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensor exhibited improved acetone gas sensing response of 12.1(R_(g)/R_(a))at room temperature,which were nearly 11 and 4 times higher than those of pristine Ti_(3)C_(2)T_(x) and pristine SnO-SnO_(2),respectively.Moreover,it expressed a short recovery time(9 s)and outstanding reproducibility.Because of the different work functions,the Schottky barrier was formed between the SnO and the Ti_(3)C_(2)T_(x) nanosheets,acting as a hole accumulation layer(HALs)between Ti_(3)C_(2)T_(x) and tin oxides.Herein,the sensing mechanism based on the formation of hetero-junctions and high conductivity of the metallic phase of Ti_(3)C_(2)T_(x) MXene in SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensors was discussed in detail.

Highly sensitive acetone gas sensor based on ultra-low content bimetallic PtCu modified WO3·H2O hollow sphere

Acetone is an important industrial raw material as well as biomarker in medical diagnosis.The detection of acetone has great significance for safety and health.However,high selectivity and low concentration(ppb level)detection remain challenges for semiconductor gas sensor.Herein,we present a novel sensitive material with bimetallic PtCu nanocrystal modified on WO3·H2O hollow spheres(HS),which shows high sensitivity,excellent selectivity,fast response/recovery speed and low limit of detection(LOD)to acetone detection.Noteworthy,the response(Ra/Rg)of WO3·H2O HS sensor increased by 9.5 times after modification with 0.02%bimetallic PtCu nanocrystals.The response of PtCu/WO3·H2O HS to 50 ppm acetone is as high as 204.9 with short response/recovery times(3.4 s/7.5 s).Finally,the gassensitivity mechanism was discussed based on gas sensitivity test results.This research will offer a new route for high efficient acetone detection.

Acetone Sensors Based on La^(3+) Doped ZnO Nano-rods Prepared by Solvothermal Method

La3＋ doped ZnO nano-rods with different doping concentration were prepared via solvothermal method.The doped ZnO nano-rods were characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）,respectively.The effect of La3＋ doping on the gas-sensing properties was investigated.The results revealed that the sensor based on 6 mol% La3＋ doped ZnO nano-rods exhibited high response to dilute acetone,and the responses to 0.01×10-6 acetone reached 2.4 when operating at 425 ℃.The response time and the recovery time for 0.01×10-6 acetone were only 16 and 3 s,respectively.