Ultrasensitive H2S gas sensors based on p-type WS2 hybrid materials
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Owing to their higher intrinsic electrical conductivity and chemical stability with respect to their oxide counterparts, nanostructured metal sulfides are expected to revive materials for resistive chemical sensor applications. Herein, we explore the gas sensing behavior of WS2 nanowire-nanoflake hybrid materials and demonstrate their excellent sensitivity (0.043 ppm-1) as well as high selectivity towards H2S relative to CO, NH3, H2, and NO (with corresponding sensitivities of 0.002, 0.0074, 0.0002, and 0.0046 ppm-1, respectively). Gas response measurements, complemented with the results of X-ray photoelectron spectroscopy analysis and first-principles calculations based on density functional theory, suggest that the intrinsic electronic properties of pristine WS2 alone are not sufficient to explain the observed high sensitivity towards H2S. A major role in this behavior is also played by O doping in the S sites of the WS2 lattice. The results of the present study open up new avenues for the use of transition metal disulfide nanomaterials as effective alternatives to metal oxides in future applications for industrial process control, security, and health and environmental safety.
KeywordsWS2 nanowire nanoflake gas sensor H2S O doping
Funding received from Bio4Energy programme, Academy of Finland (projects Suplacat and ClintoxNP (No. 268944)), University of Oulu (More than Moore research community) and University of Oulu Graduate School (Infotech Oulu) is acknowledged. We acknowledge support from the EU (No. ERC-2016-AdG-694097 QSpec-NewMat) and the Basque Government “Grupos Consolidados UPV/EHU” (No. IT578-13). J. J. B. and L. D. X. thank the EU for the Marie Curie Fellowship (Nos. H2020-MSCA-IF-2016-751047 and H2020-MSCA-IF-2015-709382). A. P. P. thanks postdoctoral fellowship from the Spanish “Juan de la Cierva-incorporación” program (No. IJCI-2014-20147). We also would like to acknowledge Sami Saukko (Center of Microscopy and Nanotechnology, University of Oulu) for his assistance with TEM analyses. A. L. S. acknowledges the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU No. 2009-00971).
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Funding: Open access funding provided by Max Planck Society.
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