Hydrogen is considered to be the subsequent energy source derived from hydrogen evolution reactions. To ensure safety when using this harmful gas, hydrogen gas sensors with fast response and recovery rates, high sensor responses and stability are crucial. There is a need for alternative materials to obtain good performance. A high surface to volume ratio with complete adsorption and desorption of ions makes molybdenum disulfide (MoS2) a promising material in hydrogen gas sensors.
We deposited a uniform MoS2 thin film by surface modification and solvent miscellany, crystallization and tunable grain size by annealing and sulfurization facilitates the implementation of MoS2 thin films as buffer layers. MoS2 is a layered material and is not soluble in any solvent and the dispersion will not be uniform which can be solved with our solvent system. To use MoS2 as a buffer layer, many factors are significant in controlling the parameters without affecting the material chemical characteristics. Thermal treatment with modulated sulfurization reforms the grain morphology yielding the flexibility of usage in more applications. MoS2 uniform thin film showed ultra-fast response and recovery rates of approximately 3 and 2.5 s for low concentrations of hydrogen gas and change is sensitivity for a small change in temperature. Cost-effective growth, deposition and fabrication techniques is a breakthrough for metal sulfide thin films.
A highly sensitive hydrogen gas sensor composed of an MoS2-Pt nanoparticle thin film as the active layer is introduced. The sensor achieved ultra-fast response and recovery rates of 4 s and 19 s, respectively, for 100 ppm of H2. The MoS2-Pt composite film exhibits a high sensor response of 10 when exposed to 100 ppm of H2 gas, which outperforms the existing metal sulfide- based sensors. The stability of the device over a period of 70 days and the selectivity of the device is outstanding. A plausible mechanism for the MoS2-Pt based H2 gas sensor is discussed. Furthermore, the sensitivity, response and recovery rates for various concentrations of H2 gas are studied. The sensor response is exceptionally promising. We also deposited WS2-Pt composites and obtained ultra-fast response and recovery rates. This sensor with metal sulfide-platinum composite active layers can be applied in the sensor field to amplify the sensing performance.
A sensor with a zinc oxide (ZnO) active layer and an MoS2 nanosheet catalyst bridged between the patterned silver electrodes was fabricated to determine the effect of temperature in gas sensors. The experimental results were comparatively very good in two ways: 1) The sensor response was high, 2) the response rate for 100 ppm H2 gas was 7 s, and the recovery rate was 23 s at 250°C with extremely high error-free repeatability. The stability of the device was noteworthy. This cost-effective, high-performance device structure can be used as a practical industrial sensor.
Additionally, we introduced a new insight into using pseudohalide CuSCN in hydrogen gas sensors. A sensor device with an electrodeposited p-type β-CuSCN nanorod thin film as an active layer was used to obtain effective gas sensing. Densely distributed nanorods as a medium of charge transfer exhibited an excellent sensor response towards H2, with fast response and recovery rates of 6 s and 7 s, respectively. Further, the stability of the device is noteworthy. This work can significantly improve the use of pseudohalides in the field of gas sensors.

[1] S. Manzeli, D. Ovchinnikov, D. Pasquier, O.V. Yazyev, A. Kis, 2D transition metal dichalcogenides, Nature Reviews Materials, 2 (2017) 17033.
[2] J. He, K. Hummer, C. Franchini, Stacking effects on the electronic and optical properties of bilayer transition metal dichalcogenides MoS 2, MoSe 2, WS 2, and WSe 2, Physical Review B, 89 (2014) 075409.
[3] J.A. Wilson, A. Yoffe, The transition metal dichalcogenides discussion and interpretation of the observed optical, electrical and structural properties, Advances in Physics, 18 (1969) 193-335.
[4] M.R. Hilton, R. Bauer, S.V. Didziulis, M.T. Dugger, J.M. Keem, J. Scholhamer, Structural and tribological studies of MoS2 solid lubricant films having tailored metal-multilayer nanostructures, Surface and Coatings Technology, 53 (1992) 13-23.
[5] Q.H. Wang, K. Kalantar-Zadeh, A. Kis, J.N. Coleman, M.S. Strano, Electronics and optoelectronics of two-dimensional transition metal dichalcogenides, Nature nanotechnology, 7 (2012) 699-712.
[6] K.E. Cox, K.D. Williamson Jr, Hydrogen-Its technology and implications. Volume 4-Utilization of hydrogen, brf, (1979).
[7] T. Hübert, L. Boon-Brett, G. Black, U. Banach, Hydrogen sensors–a review, Sensors and Actuators B: Chemical, 157 (2011) 329-352.
[8] D. Cecere, E. Giacomazzi, A. Ingenito, A review on hydrogen industrial aerospace applications, International journal of hydrogen energy, 39 (2014) 10731-10747.
[9] J. Zheng, J. Nash, B. Xu, Y. Yan, Perspective—towards establishing apparent hydrogen binding energy as the descriptor for hydrogen oxidation/evolution reactions, Journal of The Electrochemical Society, 165 (2018) H27-H29.
[10] A. Wood, H. He, T. Joia, M. Krivy, D. Steedman, Communication—Electrolysis at high efficiency with remarkable hydrogen production rates, Journal of the electrochemical society, 163 (2016) F327-F329.
[11] X. Li, X. Li, Z. Li, J. Wang, J. Zhang, WS2 nanoflakes based selective ammonia sensors at room temperature, Sensors and Actuators B: Chemical, 240 (2017) 273-277.
[12] K. Suematsu, K. Watanabe, M. Yuasa, T. Kida, K. Shimanoe, Effect of Ambient Oxygen Partial Pressure on the Hydrogen Response of SnO2 Semiconductor Gas Sensors, Journal of The Electrochemical Society, 166 (2019) B618-B622.
[13] Z. Wei, Q. Zhou, J. Wang, Y. Gui, W. Zeng, A novel porous NiO nanosheet and its H2 sensing performance, Materials Letters, (2019).
[14] J. Xia, J. Liu, G. Huang, Q. Liu, H. Zhang, X. Jing, Y. Yuan, J. Wang, Morphology controllable synthesis of NiCo2S4 and application as gas sensors, Materials Letters, 188 (2017) 17-20.
[15] N.L.W. Septiani, B. Yuliarto, The development of gas sensor based on carbon nanotubes, Journal of The Electrochemical Society, 163 (2016) B97-B106.
[16] T.M. David, P. Sagayaraj, P. Wilson, C. Ramesh, N. Murugesan, E. Prabhu, A.S.R. Murthy, S. Annapoorani, Room temperature hydrogen sensing of Pt loaded TiO2 nanotubes powders prepared via rapid breakdown anodization, Journal of The Electrochemical Society, 163 (2016) B15-B18.
[17] W. Choi, N. Choudhary, G.H. Han, J. Park, D. Akinwande, Y.H. Lee, Recent development of two-dimensional transition metal dichalcogenides and their applications, Materials Today, 20 (2017) 116-130.
[18] V.K. Sangwan, M.C. Hersam, Electronic transport in two-dimensional materials, Annual review of physical chemistry, 69 (2018) 299-325.
[19] Y. Zhu, S. Murali, W. Cai, X. Li, J.W. Suk, J.R. Potts, R.S. Ruoff, Graphene and graphene oxide: synthesis, properties, and applications, Advanced materials, 22 (2010) 3906-3924.
[20] X. Huang, Z. Yin, S. Wu, X. Qi, Q. He, Q. Zhang, Q. Yan, F. Boey, H. Zhang, Graphene‐based materials: synthesis, characterization, properties, and applications, small, 7 (2011) 1876-1902.
[21] M.-L. Tsai, S.-H. Su, J.-K. Chang, D.-S. Tsai, C.-H. Chen, C.-I. Wu, L.-J. Li, L.-J. Chen, J.-H. He, Monolayer MoS2 heterojunction solar cells, ACS nano, 8 (2014) 8317-8322.
[22] J.T. Qiu, S. Samanta, M. Dutta, S. Ginnaram, S. Maikap, Controlling Resistive Switching by Using an Optimized MoS2 Interfacial Layer and the Role of Top Electrodes on Ascorbic Acid Sensing in TaO x-Based RRAM, Langmuir, 35 (2019) 3897-3906.
[23] H. Tang, J. Wang, H. Yin, H. Zhao, D. Wang, Z. Tang, Growth of Polypyrrole Ultrathin Films on MoS2 Monolayers as High‐Performance Supercapacitor Electrodes, Advanced materials, 27 (2015) 1117-1123.
[24] X. Wang, P. Wang, J. Wang, W. Hu, X. Zhou, N. Guo, H. Huang, S. Sun, H. Shen, T. Lin, Ultrasensitive and broadband MoS2 photodetector driven by ferroelectrics, Advanced Materials, 27 (2015) 6575-6581.
[25] Y. Li, H. Wang, L. Xie, Y. Liang, G. Hong, H. Dai, MoS2 nanoparticles grown on graphene: an advanced catalyst for the hydrogen evolution reaction, Journal of the American Chemical Society, 133 (2011) 7296-7299.
[26] M. Donarelli, S. Prezioso, F. Perrozzi, F. Bisti, M. Nardone, L. Giancaterini, C. Cantalini, L. Ottaviano, Response to NO2 and other gases of resistive chemically exfoliated MoS2-based gas sensors, Sensors and Actuators B: Chemical, 207 (2015) 602-613.
[27] E.W. Keong Koh, C.H. Chiu, Y.K. Lim, Y.-W. Zhang, H. Pan, Hydrogen adsorption on and diffusion through MoS2 monolayer: First-principles study, International Journal of Hydrogen Energy, 37 (2012) 14323-14328.
[28] D.H. Youn, C. Jo, J.Y. Kim, J. Lee, J.S. Lee, Ultrafast synthesis of MoS2 or WS2-reduced graphene oxide composites via hybrid microwave annealing for anode materials of lithium ion batteries, Journal of Power Sources, 295 (2015) 228-234.
[29] K. Gopalakrishnan, S. Sultan, A. Govindaraj, C. Rao, Supercapacitors based on composites of PANI with nanosheets of nitrogen-doped RGO, BC1. 5N, MoS2 and WS2, Nano Energy, 12 (2015) 52-58.
[30] W. Yin, L. Yan, J. Yu, G. Tian, L. Zhou, X. Zheng, X. Zhang, Y. Yong, J. Li, Z. Gu, High-throughput synthesis of single-layer MoS2 nanosheets as a near-infrared photothermal-triggered drug delivery for effective cancer therapy, ACS nano, 8 (2014) 6922-6933.
[31] M. Pumera, A.H. Loo, Layered transition-metal dichalcogenides (MoS2 and WS2) for sensing and biosensing, TrAC Trends in Analytical Chemistry, 61 (2014) 49-53.
[32] K. Chang, X. Hai, H. Pang, H. Zhang, L. Shi, G. Liu, H. Liu, G. Zhao, M. Li, J. Ye, Targeted Synthesis of 2H‐and 1T‐Phase MoS2 Monolayers for Catalytic Hydrogen Evolution, Advanced Materials, 28 (2016) 10033-10041.
[33] G. Eda, H. Yamaguchi, D. Voiry, T. Fujita, M. Chen, M. Chhowalla, Photoluminescence from chemically exfoliated MoS2, Nano letters, 11 (2011) 5111-5116.
[34] K. Gacem, M. Boukhicha, Z. Chen, A. Shukla, High quality 2D crystals made by anodic bonding: a general technique for layered materials, Nanotechnology, 23 (2012) 505709.
[35] Z. Zeng, Z. Yin, X. Huang, H. Li, Q. He, G. Lu, F. Boey, H. Zhang, Single‐Layer Semiconducting Nanosheets: High‐yield preparation and device fabrication, Angewandte Chemie International Edition, 50 (2011) 11093-11097.
[36] J.N. Coleman, M. Lotya, A. O’Neill, S.D. Bergin, P.J. King, U. Khan, K. Young, A. Gaucher, S. De, R.J. Smith, Two-dimensional nanosheets produced by liquid exfoliation of layered materials, Science, 331 (2011) 568-571.
[37] Y.H. Lee, X.Q. Zhang, W. Zhang, M.T. Chang, C.T. Lin, K.D. Chang, Y.C. Yu, J.T.W. Wang, C.S. Chang, L.J. Li, Synthesis of large‐area MoS2 atomic layers with chemical vapor deposition, Advanced materials, 24 (2012) 2320-2325.
[38] Y. Yu, C. Li, Y. Liu, L. Su, Y. Zhang, L. Cao, Controlled scalable synthesis of uniform, high-quality monolayer and few-layer MoS 2 films, Scientific reports, 3 (2013) 1866.
[39] W.-J. Li, E.-W. Shi, J.-M. Ko, Z.-z. Chen, H. Ogino, T. Fukuda, Hydrothermal synthesis of MoS2 nanowires, Journal of Crystal Growth, 250 (2003) 418-422.
[40] S.P. Vattikuti, C. Byon, C.V. Reddy, Synthesis of MoS2 multi-wall nanotubes using wet chemical method with H2O2 as growth promoter, Superlattices and Microstructures, 85 (2015) 124-132.
[41] C. Wagner, The mechanism of the decomposition of nitrous oxide on zinc oxide as catalyst, The Journal of Chemical Physics, 18 (1950) 69-71.
[42] M. Law, H. Kind, B. Messer, F. Kim, P. Yang, Photochemical sensing of NO2 with SnO2 nanoribbon nanosensors at room temperature, Angewandte Chemie International Edition, 41 (2002) 2405-2408.
[43] E. Comini, G. Faglia, G. Sberveglieri, Z. Pan, Z.L. Wang, Stable and highly sensitive gas sensors based on semiconducting oxide nanobelts, Applied Physics Letters, 81 (2002) 1869-1871.
[44] Q. He, Z. Zeng, Z. Yin, H. Li, S. Wu, X. Huang, H. Zhang, Fabrication of flexible MoS2 thin‐film transistor arrays for practical gas‐sensing applications, Small, 8 (2012) 2994-2999.
[45] D.J. Late, Y.-K. Huang, B. Liu, J. Acharya, S.N. Shirodkar, J. Luo, A. Yan, D. Charles, U.V. Waghmare, V.P. Dravid, Sensing behavior of atomically thin-layered MoS2 transistors, ACS nano, 7 (2013) 4879-4891.
[46] C. Kuru, C. Choi, A. Kargar, D. Choi, Y.J. Kim, C.H. Liu, S. Yavuz, S. Jin, MoS2 nanosheet–Pd nanoparticle composite for highly sensitive room temperature detection of hydrogen, Advanced Science, 2 (2015) 1500004.
[47] A. Sanger, A. Kumar, A. Kumar, R. Chandra, Highly sensitive and selective hydrogen gas sensor using sputtered grown Pd decorated MnO2 nanowalls, Sensors and Actuators B: Chemical, 234 (2016) 8-14.
[48] S. Mourya, A. Kumar, J. Jaiswal, G. Malik, B. Kumar, R. Chandra, Development of Pd-Pt functionalized high performance H2 gas sensor based on silicon carbide coated porous silicon for extreme environment applications, Sensors and Actuators B: Chemical, 283 (2019) 373-383.
[49] J.L. Johnson, A. Behnam, S. Pearton, A. Ural, Hydrogen sensing using Pd‐functionalized multi‐layer graphene nanoribbon networks, Advanced materials, 22 (2010) 4877-4880.
[50] H.-T. Wang, B.S. Kang, F. Ren, L.-C. Tien, P. Sadik, D. Norton, S. Pearton, J. Lin, Hydrogen-selective sensing at room temperature with ZnO nanorods, Applied Physics Letters, 86 (2005) 243503.
[51] D.E. Motaung, G.H. Mhlongo, P.R. Makgwane, B.P. Dhonge, F.R. Cummings, H.C. Swart, S.S. Ray, Ultra-high sensitive and selective H2 gas sensor manifested by interface of n–n heterostructure of CeO2-SnO2 nanoparticles, Sensors and Actuators B: Chemical, 254 (2018) 984-995.
[52] A. Umar, H. Ammar, R. Kumar, T. Almas, A.A. Ibrahim, M. AlAssiri, M. Abaker, S. Baskoutas, Efficient H2 gas sensor based on 2D SnO2 disks: Experimental and theoretical studies, International Journal of Hydrogen Energy, (2019).
[53] C. Kuru, D. Choi, A. Kargar, C.H. Liu, S. Yavuz, C. Choi, S. Jin, P.R. Bandaru, High-performance flexible hydrogen sensor made of WS2 nanosheet–Pd nanoparticle composite film, Nanotechnology, 27 (2016) 195501.
[54] U.T. Nakate, G.H. Lee, R. Ahmad, P. Patil, D.P. Bhopate, Y. Hahn, Y. Yu, E.-k. Suh, Hydrothermal synthesis of p-type nanocrystalline NiO nanoplates for high response and low concentration hydrogen gas sensor application, Ceramics International, 44 (2018) 15721-15729.
[55] J. Yang, Y. Gu, E. Lee, H. Lee, S.H. Park, M.-H. Cho, Y.H. Kim, Y.-H. Kim, H. Kim, Wafer-scale synthesis of thickness-controllable MoS 2 films via solution-processing using a dimethylformamide/n-butylamine/2-aminoethanol solvent system, Nanoscale, 7 (2015) 9311-9319.
[56] R. Shahzad, T. Kim, S.-W. Kang, Effects of temperature and pressure on sulfurization of molybdenum nano-sheets for MoS2 synthesis, Thin Solid Films, 641 (2017) 79-86.
[57] J.V. Pondick, J.M. Woods, J. Xing, Y. Zhou, J.J. Cha, Stepwise Sulfurization from MoO3 to MoS2 via Chemical Vapor Deposition, ACS Applied Nano Materials, 1 (2018) 5655-5661.
[58] S. Kajita, T. Nakayama, J. Yamauchi, Density functional calculation of work function using charged slab systems, in: Journal of Physics: Conference Series, IOP Publishing, 2006, pp. 120.
[59] D. Cahen, A. Kahn, Electron energetics at surfaces and interfaces: concepts and experiments, Advanced Materials, 15 (2003) 271-277.
[60] K. Wandelt, The local work function: Concept and implications, Applied Surface Science, 111 (1997) 1-10.
[61] J.H. Kim, J. Lee, J.H. Kim, C. Hwang, C. Lee, J.Y. Park, Work function variation of MoS2 atomic layers grown with chemical vapor deposition: The effects of thickness and the adsorption of water/oxygen molecules, Applied Physics Letters, 106 (2015) 251606.
[62] S. Choi, Z. Shaolin, W. Yang, Layer-number-dependent work function of MoS 2 nanoflakes, Journal of the Korean Physical Society, 64 (2014) 1550-1555.
[63] X. Wang, H. Feng, Y. Wu, L. Jiao, Controlled synthesis of highly crystalline MoS2 flakes by chemical vapor deposition, Journal of the American Chemical Society, 135 (2013) 5304-5307.
[64] D. Ge, Y. Li, L. Yang, Z. Fan, C. Liu, X. Zhang, Improved self-assembly through UV/ozone surface-modification of colloidal spheres, Thin Solid Films, 519 (2011) 5203-5207.
[65] A. Politano, M. Vitiello, L. Viti, D. Boukhvalov, G. Chiarello, The role of surface chemical reactivity in the stability of electronic nanodevices based on two-dimensional materials “beyond graphene” and topological insulators, FlatChem, 1 (2017) 60-64.
[66] Q. Chen, H. Li, W. Xu, S. Wang, H. Sawada, C.S. Allen, A.I. Kirkland, J.C. Grossman, J.H. Warner, Atomically flat zigzag edges in monolayer MoS2 by thermal annealing, Nano letters, 17 (2017) 5502-5507.
[67] E.W.K. Koh, C.H. Chiu, Y.K. Lim, Y.-W. Zhang, H. Pan, Hydrogen adsorption on and diffusion through MoS2 monolayer: First-principles study, International journal of hydrogen energy, 37 (2012) 14323-14328.
[68] Z. Qin, K. Xu, H. Yue, H. Wang, J. Zhang, C. Ouyang, C. Xie, D. Zeng, Enhanced room-temperature NH3 gas sensing by 2D SnS2 with sulfur vacancies synthesized by chemical exfoliation, Sensors and Actuators B: Chemical, 262 (2018) 771-779.
[69] A.S. Ryzhikov, A.N. Shatokhin, F.N. Putilin, M.N. Rumyantseva, A.M. Gaskov, M. Labeau, Hydrogen sensitivity of SnO2 thin films doped with Pt by laser ablation, Sensors and Actuators B: Chemical, 107 (2005) 387-391.
[70] M. Penza, C. Martucci, G. Cassano, NOx gas sensing characteristics of WO3 thin films activated by noble metals (Pd, Pt, Au) layers, Sensors and Actuators B: Chemical, 50 (1998) 52-59.
[71] S.-C. Wang, M. Shaikh, A room temperature H2 sensor fabricated using high performance Pt-loaded SnO2 nanoparticles, Sensors, 15 (2015) 14286-14297.
[72] A. Roy, S. Maikap, P.-J. Tzeng, J.T. Qiu, Sensing characteristics of dopamine using Pt/n-Si structure, Vacuum, (2019) 109050.
[73] Y. Wang, S. Wang, Y. Zhao, B. Zhu, F. Kong, D. Wang, S. Wu, W. Huang, S. Zhang, H2S sensing characteristics of Pt-doped α-Fe2O3 thick film sensors, Sensors and Actuators B: Chemical, 125 (2007) 79-84.
[74] M. Tiemann, Porous metal oxides as gas sensors, Chemistry–A European Journal, 13 (2007) 8376-8388.
[75] J.L. Rowsell, O.M. Yaghi, Strategies for hydrogen storage in metal–organic frameworks, Angewandte Chemie International Edition, 44 (2005) 4670-4679.
[76] G. Korotcenkov, V. Brinzari, Y. Boris, M. Ivanov, J. Schwank, J. Morante, Influence of surface Pd doping on gas sensing characteristics of SnO2 thin films deposited by spray pirolysis, Thin Solid Films, 436 (2003) 119-126.
[77] H. Kim, Y. Pak, Y. Jeong, W. Kim, J. Kim, G.Y. Jung, Amorphous Pd-assisted H2 detection of ZnO nanorod gas sensor with enhanced sensitivity and stability, Sensors and Actuators B: Chemical, 262 (2018) 460-468.
[78] D.-H. Baek, J. Kim, MoS2 gas sensor functionalized by Pd for the detection of hydrogen, Sensors and Actuators B: Chemical, 250 (2017) 686-691.
[79] L. Hao, Y. Liu, W. Gao, Y. Liu, Z. Han, L. Yu, Q. Xue, J. Zhu, High hydrogen sensitivity of vertically standing layered MoS 2/Si heterojunctions, Journal of Alloys and Compounds, 682 (2016) 29-34.
[80] B. Cho, J. Yoon, S.K. Lim, A.R. Kim, S.-Y. Choi, D.-H. Kim, K.H. Lee, B.H. Lee, H.C. Ko, M.G. Hahm, Metal decoration effects on the gas-sensing properties of 2D hybrid-structures on flexible substrates, Sensors, 15 (2015) 24903-24913.
[81] L. Hao, Y. Liu, Y. Du, Z. Chen, Z. Han, Z. Xu, J. Zhu, Highly Enhanced H2 Sensing Performance of Few-Layer MoS2/SiO2/Si Heterojunctions by Surface Decoration of Pd Nanoparticles, Nanoscale research letters, 12 (2017) 567.
[82] K.-C. Huang, Y.-C. Wang, P.-Y. Chen, Y.-H. Lai, J.-H. Huang, Y.-H. Chen, R.-X. Dong, C.-W. Chu, J.-J. Lin, K.-C. Ho, High performance dye-sensitized solar cells based on platinum nanoparticle/multi-wall carbon nanotube counter electrodes: The role of annealing, Journal of Power Sources, 203 (2012) 274-281.
[83] F. Şen, G. Gökaǧaç, Different sized platinum nanoparticles supported on carbon: an XPS study on these methanol oxidation catalysts, The Journal of Physical Chemistry C, 111 (2007) 5715-5720.
[84] Z. Mei, Y. Li, M. Fan, L. Zhao, J. Zhao, Effect of the interactions between Pt species and ceria on Pt/ceria catalysts for water gas shift: The XPS studies, Chemical Engineering Journal, 259 (2015) 293-302.
[85] K. Yang, J. Li, Y. Peng, J. Lin, Enhanced visible light photocatalysis over Pt-loaded Bi 2 O 3: an insight into its photogenerated charge separation, transfer and capture, Physical Chemistry Chemical Physics, 19 (2017) 251-257.
[86] M.A. Matin, E. Lee, H. Kim, W.-S. Yoon, Y.-U. Kwon, Rational syntheses of core–shell Fe@(PtRu) nanoparticle electrocatalysts for the methanol oxidation reaction with complete suppression of CO-poisoning and highly enhanced activity, Journal of Materials Chemistry A, 3 (2015) 17154-17164.
[87] M. Wang, L. Zhang, M. Huang, Q. Zhang, X. Zhao, Y. He, S. Lin, J. Pan, H. Zhu, One-step synthesis of a hierarchical self-supported WS2 film for efficient electrocatalytic hydrogen evolution, Journal of Materials Chemistry A, 7 (2019) 22405-22411.
[88] S.R. Gottam, C.-T. Tsai, L.-W. Wang, C.-T. Wang, C.-C. Lin, S.-Y. Chu, Highly sensitive hydrogen gas sensor based on a MoS2-Pt nanoparticle composite, Applied Surface Science, 506 (2020) 144981.
[89] W. Wang, X. Liu, S. Mei, Y. Jia, M. Liu, X. Xue, D. Yang, Development of a Pd/Cu nanowires coated SAW hydrogen gas sensor with fast response and recovery, Sensors and Actuators B: Chemical, 287 (2019) 157-164.
[90] G.B. Pour, L.F. Aval, S. Eslami, Sensitive capacitive-type hydrogen sensor based on Ni thin film in different hydrogen concentrations, Current nanoscience, 14 (2018) 136-142.
[91] Y.-R. Lo, H.-M.P. Chen, Y.-S. Yang, M.-P. Lu, Gas Sensing Ability on Polycrystalline-Silicon Nanowire, ECS Journal of Solid State Science and Technology, 7 (2018) Q3104-Q3107.
[92] S. Jang, S. Jung, K.H. Baik, The Dependence of Crystal Plane on Hydrogen Sensing Properties of ZnO Bulk Substrates, ECS Journal of Solid State Science and Technology, 8 (2019) Q85-Q88.
[93] M. Weber, J.-Y. Kim, J.-H. Lee, J.-H. Kim, I. Iatsunskyi, E. Coy, P. Miele, M. Bechelany, S.S. Kim, Highly efficient hydrogen sensors based on Pd nanoparticles supported on boron nitride coated ZnO nanowires, Journal of materials chemistry A, 7 (2019) 8107-8116.
[94] V.S. Bhati, S. Ranwa, S. Rajamani, K. Kumari, R. Raliya, P. Biswas, M. Kumar, Improved sensitivity with low limit of detection of a hydrogen gas sensor based on rGO-loaded Ni-doped ZnO nanostructures, ACS applied materials & interfaces, 10 (2018) 11116-11124.
[95] A. Narayana, S.A. Bhat, A. Fathima, S.V. Lokesh, S.G. Surya, C.V. Yelamaggad, Green and low-cost synthesis of zinc oxide nanoparticles and their application in transistor-based carbon monoxide sensing, RSC Advances, 10 (2020) 13532-13542.
[96] X. Gao, H. Zhao, J. Wang, X. Su, F. Xiao, Morphological evolution of flower-like ZnO microstructures and their gas sensing properties, Ceramics International, 39 (2013) 8629-8632.
[97] B. Renganathan, A. Ganesan, Fiber optic gas sensor with nanocrystalline ZnO, Optical Fiber Technology, 20 (2014) 48-52.
[98] Y. Zhang, W. Zeng, Y. Li, The hydrothermal synthesis of 3D hierarchical porous MoS2 microspheres assembled by nanosheets with excellent gas sensing properties, Journal of Alloys and Compounds, 749 (2018) 355-362.
[99] Y.-S. Tsai, T.-W. Chou, C.Y. Xu, W.C. Huang, C.F. Lin, Y.S. Wu, Y.-S. Lin, H. Chen, ZnO/ZnS core-shell nanostructures for hydrogen gas sensing performances, Ceramics International, 45 (2019) 17751-17757.
[100] C. Song, M. Sun, Y. Yin, J. Xiao, W. Dong, C. Li, L. Zhang, Synthesis of star-shaped lead sulfide (PbS) nanomaterials and theirs gas-sensing properties, Materials Research, 19 (2016) 1351-1355.
[101] D. Sun, X. Miao, J. Yang, H. Li, X. Zhou, Z. Lei, MoS2 Nanosheets Vertically Aligned on Hierarchically Porous Graphitic Carbon for High-Performance Lithium Storage, Journal of The Electrochemical Society, 165 (2018) A2859-A2865.
[102] M. Ikram, Y. Liu, H. Lv, L. Liu, A.U. Rehman, K. Kan, W. Zhang, L. He, Y. Wang, R. Wang, 3D-multilayer MoS2 nanosheets vertically grown on highly mesoporous cubic In2O3 for high-performance gas sensing at room temperature, Applied Surface Science, 466 (2019) 1-11.
[103] T.F. Choo, N.U. Saidin, K.Y. Kok, Hydrogen sensing enhancement of zinc oxide nanorods via voltage biasing, Royal Society open science, 5 (2018) 172372.
[104] C.S. Rout, S.H. Krishna, S. Vivekchand, A. Govindaraj, C. Rao, Hydrogen and ethanol sensors based on ZnO nanorods, nanowires and nanotubes, Chemical Physics Letters, 418 (2006) 586-590.
[105] T. Wang, X. Kou, L. Zhao, P. Sun, C. Liu, Y. Wang, K. Shimanoe, N. Yamazoe, G. Lu, Flower-like ZnO hollow microspheres loaded with CdO nanoparticles as high performance sensing material for gas sensors, Sensors and Actuators B: Chemical, 250 (2017) 692-702.
[106] T.J. Chang, T.J. Hsueh, A NO2 Gas Sensor with a TiO2 Nanoparticles/ZnO/MEMS-Structure that is Produced Using Ultrasonic Wave Grinding Technology, Journal of The Electrochemical Society, 167 (2020) 027521.
[107] P. Lin, X. Chen, K. Zhang, H. Baumgart, Improved Gas Sensing Performance of ALD AZO 3-D Coated ZnO Nanorods, ECS Journal of Solid State Science and Technology, 7 (2018) Q246.
[108] D. Zhang, H. Chang, Y. Zhang, Fabrication of palladium–zinc oxide–reduced graphene oxide hybrid for hydrogen gas detection at low working temperature, Journal of Materials Science: Materials in Electronics, 28 (2017) 1667-1673.
[109] D. Zhang, C. Jiang, Y. Zhang, Room temperature hydrogen gas sensor based on palladium decorated tin oxide/molybdenum disulfide ternary hybrid via hydrothermal route, Sensors and Actuators B: Chemical, 242 (2017) 15-24.
[110] J.-H. Kim, A. Mirzaei, H.W. Kim, S.S. Kim, Pd functionalization on ZnO nanowires for enhanced sensitivity and selectivity to hydrogen gas, Sensors and Actuators B: Chemical, 297 (2019) 126693.
[111] U.T. Nakate, R. Ahmad, P. Patil, Y. Wang, K.S. Bhat, T. Mahmoudi, Y. Yu, E.-k. Suh, Y.-B. Hahn, Improved selectivity and low concentration hydrogen gas sensor application of Pd sensitized heterojunction n-ZnO/p-NiO nanostructures, Journal of Alloys and Compounds, 797 (2019) 456-464.
[112] H. Yan, P. Song, S. Zhang, Z. Yang, Q. Wang, Facile synthesis, characterization and gas sensing performance of ZnO nanoparticles-coated MoS2 nanosheets, Journal of Alloys and Compounds, 662 (2016) 118-125.
[113] S. Phanichphant, Semiconductor metal oxides as hydrogen gas sensors, Procedia Eng, 87 (2014) 795-802.
[114] J. Hassan, M. Mahdi, C. Chin, H. Abu-Hassan, Z. Hassan, A high-sensitivity room-temperature hydrogen gas sensor based on oblique and vertical ZnO nanorod arrays, Sensors and Actuators B: Chemical, 176 (2013) 360-367.
[115] A.Z. Sadek, S. Choopun, W. Wlodarski, S.J. Ippolito, K. Kalantar-zadeh, Characterization of ZnO Nanobelt-Based Gas Sensor for ${
m H} _ {2} $, ${
m NO} _ {2} $, and Hydrocarbon Sensing, IEEE Sensors Journal, 7 (2007) 919-924.
[116] B. Mondal, B. Basumatari, J. Das, C. Roychaudhury, H. Saha, N. Mukherjee, ZnO–SnO2 based composite type gas sensor for selective hydrogen sensing, Sensors and Actuators B: Chemical, 194 (2014) 389-396.
[117] S.M. Hatch, J. Briscoe, S. Dunn, A self‐powered ZnO‐nanorod/CuSCN UV photodetector exhibiting rapid response, Advanced Materials, 25 (2013) 867-871.
[118] C.-T. Tsai, S.R. Gottam, P.-C. Kao, D.-C. Perng, S.-Y. Chu, Organic light-emitting diodes with an electro-deposited copper (I) thiocyanate (CuSCN) hole-injection layer based on aqueous electrolyte, Synthetic Metals, 256 (2019) 116156.
[119] H. Dong, Z. Wu, J. Xi, X. Xu, L. Zuo, T. Lei, X. Zhao, L. Zhang, X. Hou, A.K.Y. Jen, Perovskite Photovoltaics: Pseudohalide‐Induced Recrystallization Engineering for CH3NH3PbI3 Film and Its Application in Highly Efficient Inverted Planar Heterojunction Perovskite Solar Cells (Adv. Funct. Mater. 2/2018), Advanced Functional Materials, 28 (2018) 1870013.
[120] Y.-H. Chiang, M.-H. Li, H.-M. Cheng, P.-S. Shen, P. Chen, Mixed cation thiocyanate-based pseudohalide perovskite solar cells with high efficiency and stability, ACS applied materials & interfaces, 9 (2017) 2403-2409.
[121] E. Premalal, G. Kumara, R. Rajapakse, M. Shimomura, K. Murakami, A. Konno, Tuning chemistry of CuSCN to enhance the performance of TiO 2/N719/CuSCN all-solid-state dye-sensitized solar cell, Chemical Communications, 46 (2010) 3360-3362.
[122] P. Pattanasattayavong, G.O.N. Ndjawa, K. Zhao, K.W. Chou, N. Yaacobi-Gross, B.C. O'Regan, A. Amassian, T.D. Anthopoulos, Electric field-induced hole transport in copper (I) thiocyanate (CuSCN) thin-films processed from solution at room temperature, Chemical Communications, 49 (2013) 4154-4156.
[123] C. Lévy‐Clément, R. Tena‐Zaera, M.A. Ryan, A. Katty, G. Hodes, CdSe‐sensitized p‐CuSCN/nanowire n‐ZnO heterojunctions, Advanced Materials, 17 (2005) 1512-1515.
[124] G. Chen, L. Wang, Y. Zou, X. Sheng, H. Liu, X. Pi, D. Yang, CdSe quantum dots sensitized mesoporous TiO 2 solar cells with CuSCN as solid-state electrolyte, Journal of Nanomaterials, 2011 (2011) 40.
[125] F. Bouhjar, S. Ullah, M. Chourou, M. Mollar, B. Marí, B. Bessaïs, Electrochemical fabrication and characterization of p-CuSCN/n-Fe2O3 heterojunction devices for hydrogen production, Journal of The Electrochemical Society, 164 (2017) H936-H945.
[126] K. Hassan, A.I. Uddin, F. Ullah, Y.S. Kim, G.-S. Chung, Platinum/palladium bimetallic ultra-thin film decorated on a one-dimensional ZnO nanorods array for use as fast response flexible hydrogen sensor, Materials Letters, 176 (2016) 232-236.
[127] R.-C. Wang, Y.-R. Hou, J.-Y. Liu, Y.-W. Chen, Differentiating Ammonia from Other Reducing Gases via Response Reversal Phenomena by Varied ZnO/CuxO Nanorod Arrays, Journal of The Electrochemical Society, 165 (2018) B484-B490.
[128] S.-J. Young, W.-L. Tang, Wireless Zinc Oxide Based pH Sensor System, Journal of The Electrochemical Society, 166 (2019) B3047-B3050.
[129] N. Fenineche, C. Coddet, A. Saida, Effect of electrodeposition parameters on the microstructure and mechanical properties of Co-Ni alloys, Surface and Coatings Technology, 41 (1990) 75-81.
[130] G.A. Asres, J.J. Baldoví, A. Dombovari, T. Järvinen, G.S. Lorite, M. Mohl, A. Shchukarev, A.P. Paz, L. Xian, J.-P. Mikkola, Ultrasensitive H 2 S gas sensors based on p-type WS 2 hybrid materials, Nano Research, 11 (2018) 4215-4224.
[131] F. Wang, D. Chen, Z. Hu, L. Qin, X. Sun, Y. Huang, In situ decoration of CuSCN nanorod arrays with carbon quantum dots for highly efficient photoelectrochemical performance, Carbon, 125 (2017) 344-351.
[132] M.-C. Huang, T. Wang, Y.-T. Tseng, C.-C. Wu, J.-C. Lin, W.-Y. Hsu, W.-S. Chang, I.-C. Chen, K.-C. Peng, Influence of annealing on microstructural and photoelectrochemical characteristics of CuSCN thin films via electrochemical process, Journal of Alloys and Compounds, 622 (2015) 669-675.
[133] L.E. Marsoner Steinkasserer, V. Pohl, B. Paulus, Cyanographone and isocyanographone—Two asymmetrically functionalized graphene pseudohalides and their potential use in chemical sensing, The Journal of chemical physics, 148 (2018) 084703.
[134] L. Tsetseris, Two-dimensional cyanates: stabilization through hydrogenation, Physical Chemistry Chemical Physics, 18 (2016) 14662-14666.
[135] J. Kim, S.D. Oh, J.H. Kim, D.H. Shin, S. Kim, S.-H. Choi, Graphene/Si-nanowire heterostructure molecular sensors, Scientific reports, 4 (2014) 5384.