Thermal stability of WS2 flakes and gas sensing properties of WS2/WO3 composite to H2, NH3 and NO2

Abstract We report on the fabrication and on the morphological, structural, chemical and the electrical characterization of WS2 thin films sensors prepared by drop casting a commercial solution of dispersed few-layers WS2 flakes on Si3N4 interdigitated substrates and annealing the films in air at 150 °C, 250 °C and 350 °C. Thermal stability of WS2 in air at different annealing temperatures has been investigated by X-ray photoemission spectroscopy, scanning electron microscopy, X-ray diffraction and by simultaneous thermal analysis techniques. We found that WS2 is not stable in air and partially oxidizes to amorphous WO3 in the annealing temperature range 25 °C–150 °C. The oxidation of WS2 in air at 250 °C and 350 °C yields a composite crystalline WS2/WO3 hierarchical structure characterized by the presence of surface oxygen and sulphur vacancies. The contribution of each phase of the WS2/WO3 composite to the overall chemoresistive gas response utilizing H2 (1–10 ppm), NH3 (1–10 ppm) and NO2 (40 ppb–1 ppm) gases in dry air carrier is presented and discussed. WS2/WO3 composite films show excellent gas sensing properties to reducing (H2, NH3) as respect to oxidizing (NO2) gases at 150 °C operating temperature. In this work we found low detection limits of 1 ppm H2, 1 ppm NH3 and 100 ppm NO2 in dry air carrier, among the smallest so far ever reported for transition metal dichalcogenides. Furthermore, the sensor doesn’t show any cross sensitivity effects to both H2 and NH3 when exposed to water vapor. Outstanding reproducibility responses, by exposing the 150 °C annealed film to dynamic and cumulative gas pulses where obtained utilizing H2 gas.

[1]  Tetsuya Kida,et al.  High sensitive gas sensor based on Pd-loaded WO3 nanolamellae , 2013 .

[2]  S. Morrison,et al.  New structures from exfoliated MoS2 , 1991 .

[3]  Ruitao Lv,et al.  Transition metal dichalcogenides and beyond: synthesis, properties, and applications of single- and few-layer nanosheets. , 2015, Accounts of chemical research.

[4]  Luca Ottaviano,et al.  Graphene oxide for gas detection under standard humidity conditions , 2015 .

[5]  Chongwu Zhou,et al.  High-performance chemical sensing using Schottky-contacted chemical vapor deposition grown monolayer MoS2 transistors. , 2014, ACS nano.

[6]  C. Zhang,et al.  Sensitive and rapid hydrogen sensors based on Pd–WO3 thick films with different morphologies , 2013 .

[7]  Ib Chorkendorff,et al.  Molybdenum sulfides—efficient and viable materials for electro - and photoelectrocatalytic hydrogen evolution , 2012 .

[8]  L. Kulikov,et al.  XPS studies of the surface of nanocrystalline tungsten disulfide , 2010 .

[9]  Hua Zhang,et al.  The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. , 2013, Nature chemistry.

[10]  Jakob Kibsgaard,et al.  Size threshold in the dibenzothiophene adsorption on MoS2 nanoclusters. , 2010, ACS nano.

[11]  Carles Cané,et al.  Fabrication of WO3 nanodot-based microsensors highly sensitive to hydrogen , 2010 .

[12]  G. Ozin,et al.  Colloidal synthesis of 1T-WS2 and 2H-WS2 nanosheets: applications for photocatalytic hydrogen evolution. , 2014, Journal of the American Chemical Society.

[13]  K. Wong,et al.  Surface and friction characterization of MoS2 and WS2 third body thin films under simulated wheel/rail rolling–sliding contact , 2008 .

[14]  N. Vuong,et al.  Surface gas sensing kinetics of a WO3 nanowire sensor: part 1—oxidizing gases , 2015 .

[15]  V. Thangadurai,et al.  Revisiting tungsten trioxide hydrates (TTHs) synthesis--is there anything new? , 2009, Inorganic chemistry.

[16]  Alireza Kargar,et al.  High-performance flexible hydrogen sensor made of WS2 nanosheet–Pd nanoparticle composite film , 2016, Nanotechnology.

[17]  L. Palmisano,et al.  Coupled Semiconductor Systems for Photocatalysis. Preparation and Characterization of Polycrystalline Mixed WO3/WS2 Powders , 1999 .

[18]  Yi Cui,et al.  Physical and chemical tuning of two-dimensional transition metal dichalcogenides. , 2015, Chemical Society reviews.

[19]  N. Koratkar,et al.  Aging of Transition Metal Dichalcogenide Monolayers. , 2016, ACS nano.

[20]  Anran Liu,et al.  High‐Performance NO2 Sensors Based on Chemically Modified Graphene , 2013, Advanced materials.

[21]  W. Sawyer,et al.  Energetics of Oxidation in MoS2 Nanoparticles by Density Functional Theory , 2011 .

[22]  U. Anselmi-Tamburini,et al.  The influence of thermal and visible light activation modes on the NO2 response of WO3 nanofibers prepared by electrospinning , 2016 .

[23]  Kaustav Banerjee,et al.  Functionalization of transition metal dichalcogenides with metallic nanoparticles: implications for doping and gas-sensing. , 2015, Nano letters.

[24]  Yun Chan Kang,et al.  Highly sensitive and selective detection of ppb-level NO2 using multi-shelled WO3 yolk–shell spheres , 2016 .

[25]  Tetsuya Kida,et al.  Highly sensitive NO2 sensors using lamellar-structured WO3 particles prepared by an acidification method , 2009 .

[26]  Konrad Colbow,et al.  A highly sensitive and selective hydrogen gas sensor from thick oriented films of MoS2 , 1996 .

[27]  Xin Li,et al.  Nanosheets assembled hierarchical flower-like WO3 nanostructures: Synthesis, characterization, and their gas sensing properties , 2015 .

[28]  S. Santucci,et al.  Graphene Oxide as a Practical Solution to High Sensitivity Gas Sensing , 2013 .

[29]  L. Ottaviano,et al.  Exfoliated black phosphorus gas sensing properties at room temperature , 2016 .

[30]  Martin Pumera,et al.  Metallic 1T‐WS2 for Selective Impedimetric Vapor Sensing , 2015 .

[31]  M. Strano,et al.  Synthesis of Atomically Thin WO3 Sheets from Hydrated Tungsten Trioxide , 2010 .

[32]  J. Nørskov,et al.  Hydrogen evolution on nano-particulate transition metal sulfides. , 2008, Faraday discussions.

[33]  Benjamin J. Carey,et al.  Investigation of Two-Solvent Grinding-Assisted Liquid Phase Exfoliation of Layered MoS2 , 2015 .

[34]  Jian-Bai Xia,et al.  Photoresponsive and Gas Sensing Field-Effect Transistors based on Multilayer WS2 Nanoflakes , 2014, Scientific Reports.

[35]  R. Wallace,et al.  Surface oxidation energetics and kinetics on MoS2 monolayer , 2015 .

[36]  Qing Tang,et al.  Innovation and discovery of graphene‐like materials via density‐functional theory computations , 2015 .

[37]  Kangho Lee,et al.  Plasma assisted synthesis of WS2 for gas sensing applications , 2014 .

[38]  Carlo Cantalini,et al.  The comparative effect of two different annealing temperatures and times on the sensitivity and long-term stability of WO/sub 3/ thin films for detecting NO/sub 2/ , 2003 .

[39]  John L. Hutchison,et al.  Bulk Synthesis of Inorganic Fullerene-like MS2 (M = Mo, W) from the Respective Trioxides and the Reaction Mechanism , 1996 .

[40]  Byoung Hun Lee,et al.  Bifunctional sensing characteristics of chemical vapor deposition synthesized atomic-layered MoS2. , 2015, ACS applied materials & interfaces.

[41]  Kangho Lee,et al.  High‐Performance Sensors Based on Molybdenum Disulfide Thin Films , 2013, Advanced materials.

[42]  J. Warner,et al.  Controlled preferential oxidation of grain boundaries in monolayer tungsten disulfide for direct optical imaging. , 2015, ACS nano.

[43]  T. Zhai,et al.  Two-dimensional layered nanomaterials for gas-sensing applications , 2016 .

[44]  Qing Hua Wang,et al.  Electronics and optoelectronics of two-dimensional transition metal dichalcogenides. , 2012, Nature nanotechnology.

[45]  T. Coyle,et al.  Orthorhombic α-MoO3 Coatings with Lath-Shaped Morphology Developed by SPPS: Applications to Super-Capacitors , 2012, Journal of Thermal Spray Technology.

[46]  H. Flotow,et al.  Calorimetric measurements of the low-temperature heat capacity, standard molar enthalpy of formation at 298.15 K, and high-temperature molar enthalpy increments relative to 298.15 K of tungsten disulfide (WS2), and the thermodynamic properties to 1500 K , 1984 .

[47]  P M Campbell,et al.  Chemical vapor sensing with monolayer MoS2. , 2013, Nano letters.

[48]  Thomas F. Jaramillo,et al.  Identification of Active Edge Sites for Electrochemical H2 Evolution from MoS2 Nanocatalysts , 2007, Science.

[49]  J. Coleman,et al.  Liquid Exfoliation of Layered Materials , 2013, Science.

[50]  Desheng Kong,et al.  Synthesis of MoS2 and MoSe2 films with vertically aligned layers. , 2013, Nano letters.

[51]  Ho Won Jang,et al.  Self-Activated Transparent All-Graphene Gas Sensor with Endurance to Humidity and Mechanical Bending. , 2015, ACS nano.

[52]  Luca Ottaviano,et al.  Response to NO2 and other gases of resistive chemically exfoliated MoS2-based gas sensors , 2015 .

[53]  M. Pumera,et al.  2H → 1T phase transition and hydrogen evolution activity of MoS2, MoSe2, WS2 and WSe2 strongly depends on the MX2 composition. , 2015, Chemical communications.

[54]  M. W. Chase,et al.  NIST-JANAF Thermochemical Tables Fourth Edition , 1998 .

[55]  A. Kargar,et al.  MoS2 Nanosheet–Pd Nanoparticle Composite for Highly Sensitive Room Temperature Detection of Hydrogen , 2015, Advanced science.

[56]  S. Morrison,et al.  The intercalation and exfoliation of tungsten disulfide , 1988 .

[57]  A. Albu-Yaron,et al.  Study of the growth mechanism of WS2 nanotubes produced by a fluidized bed reactor , 2004 .

[58]  G. Tompa,et al.  Highly sensitive and selective detection of NO2 using epitaxial graphene on 6H-SiC , 2010 .

[59]  Bin Liu,et al.  Sensing behavior of atomically thin-layered MoS2 transistors. , 2013, ACS nano.

[60]  Hisato Yamaguchi,et al.  Enhanced catalytic activity in strained chemically exfoliated WS₂ nanosheets for hydrogen evolution. , 2012, Nature Materials.