H2S graphene sensor

Graphene sensor do khi H2S trong moi truong yem khi nhu nha may che bien rac thai va cac moi truong dac biet khac. Đây là phương pháp chế tạo cảm biến đơn giản, độ nhạy cao và đo được khí ở nộng độ thấp. Cấu tạo gồm nền graphen 1 hoặc 2 lớp, sau đó graphene được doping bằng cation Fe và Ag, kết quả cho thấy các chỉ số chất lượng của Graphene tốt hơn lên và màng Graphene còn có thể tạo độ nhạy cảm rất lớn với khí H2S có chọn lọc mà không có sự hấp phụ xảy ra với các loại khí phổ biến khác như N2, CO2, ..

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/320631280 Highly sensitive chemiresistive H S gas sensor based on graphene decorated with Ag nanoparticles and charged impurities Article  in  Sensors and Actuators B Chemical · October 2017 DOI: 10.1016/j.snb.2017.10.128 CITATIONS READS 147 authors, including: Oleksandr Ovsianytskyi Yun-sik Nam Technische Universität Berlin Korea Institute of Science and Technology PUBLICATIONS   4 CITATIONS    39 PUBLICATIONS   321 CITATIONS    SEE PROFILE SEE PROFILE Oleksandr Tsymbalenko Phan Lan Korea Institute of Science and Technology Dongguk University PUBLICATIONS   5 CITATIONS    PUBLICATIONS   18 CITATIONS    SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: Peptidomimetics View project Detection of toxic and bio molecules using imidazole derivatives conjugated with nano materials View project All content following this page was uploaded by Kang-Bong Lee on 19 December 2017 The user has requested enhancement of the downloaded file Sensors and Actuators B 257 (2018) 278–285 Contents lists available at ScienceDirect Sensors and Actuators B: Chemical journal homepage: www.elsevier.com/locate/snb Research paper Highly sensitive chemiresistive H2 S gas sensor based on graphene decorated with Ag nanoparticles and charged impurities Oleksandr Ovsianytskyi a,b , Yun-Sik Nam c , Oleksandr Tsymbalenko a,b , Phan-Thi Lan d , Myoung-Woon Moon d , Kang-Bong Lee a,∗ a Green City Technology Institute, Korea Institute of Science and Technology, Hwarang-ro 14 gil 5, Seoul 02792, Republic of Korea Department of Electronics, Igor Sikorsky Kyiv Polytechnic Institute, Peremohy Ave 37, Kyiv 03056, Ukraine Advanced Analysis Center, Korea Institute of Science and Technology, Hwarang-ro 14 gil 5, Seoul 02792, Republic of Korea d Computational Science Center, Korea Institute of Science and Technology, Hwarang-ro 14 gil 5, Seoul 02792, Republic of Korea b c a r t i c l e i n f o Article history: Received 14 April 2017 Received in revised form 18 October 2017 Accepted 21 October 2017 Available online 25 October 2017 Keywords: CVD graphene Chemiresistive sensor H2 S graphene sensor Graphene doping Silver nanoparticle doping a b s t r a c t Herein, we report a highly sensitive and selective H2 S gas sensor based on graphene decorated with Ag nanoparticles (AgNPs) and charged impurities fabricated using a simple wet chemical method Doping on as-grown chemical vapor deposited graphene was achieved by immersion in an aqueous solution of AgNO3 /Fe(NO3 )3 for followed by the decoration with adsorbed AgNPs and charged impurities The AgNPs utilized in this process were formed by the reduction of Ag+ ions, since the Ag+ /Ag0 reduction potential is higher than that of Fe3+ /Fe0 The above treatment changed the electronic properties of graphene, achieving a dramatic resistivity change in the presence of H2 S gas by generating surface sites for its adsorption and dissociation and thus allowing real time H2 S level monitoring at ambient temperature with an immediate response Doped graphene was demonstrated to selectively and repeatedly sense H2 S gas within six minutes, with the limit of detection being below 100 ppb The corresponding mechanism is believed to feature a charge carrier density change of graphene to adsorbate charge transfer, with the sensor surface trapping or releasing electrons upon exposure to H2 S gas © 2017 Elsevier B.V All rights reserved Introduction H2 S is a highly toxic gas which is usually produced by natural gas plants, sewage plants, and the oil industry Since exposure to high levels (100 ppm) of H2 S gas can induce an immediate collapse with loss of breathing and has high death probability, various fluorescence-based probes [1–3] and chemiresistive sensors [4–8] based on reduced graphene oxide, carbon nanotubes, and other nanocomposites have been developed for sensitive and selective room temperature H2 S detection Although graphene can also be utilized for this purpose, successful sensor applications require its electronic properties to be tuned by various doping methods [9,10] H2 S can be easily adsorbed on graphene sheets doped with transition metals, which enhance the graphene-H2 S interaction energy from − 0.1 eV (pristine graphene) to up to − eV [11–13] Moreover, the disorder in graphene plays a fundamental role in determining ∗ Corresponding author E-mail address: leekb@kist.re.kr (K.-B Lee) https://doi.org/10.1016/j.snb.2017.10.128 0925-4005/© 2017 Elsevier B.V All rights reserved its physical properties, with conductivity being affected by charged impurities [14] Herein, we aimed to fabricate a highly sensitive, selective, and low cost H2 S gas sensor with a fast room temperature response time, overcoming problems observed for previous sensors [9–11] In many cases, the sensitivity, selectivity, or both of these properties can be enhanced by decorating graphene with metal nanoparticles [12,13] by using electrochemical methods or simple wet chemical reduction of metal salts [15–18] Herein, metal nanoparticles for graphene decoration were prepared by the chemical reduction of metal salts Non-covalent functionalization of the metal salt modified graphene relies on - interactions or weak van der Waals interactions between sp2 graphene carbons and metal nanoparticles In most cases, chemical surface doping does not damage the structure of graphene and is reversible [19] Doping of graphene by adsorption of metal nanoparticles does not deteriorate carrier mobility [20], and graphene defects also play a significant role in the sensing process, achieving H2 S adsorption energies of up to − 0.91 eV [21] Sensitization by noble metals via chemical and/or electronic interactions is an efficient method for enhancing the response of O Ovsianytskyi et al / Sensors and Actuators B 257 (2018) 278–285 279 graphene toward H2 S gas, as indicated by earlier reports on iron or silver doped graphene and semiconductors used for H2 S gas sensing [22–26] Ag+ ions can be reduced to Ag nanoparticles (AgNPs) in a mixed solution of AgNO3 and Fe(NO3 )3 due to the difference of Ag+ /Ag0 and Fe3+ /Fe0 reduction potentials ( E) at acidic pH [27] In other words, the Ag+ ions of AgNO3 can be converted to AgNPs in the presence of Fe(NO3 )3 , and the above nanoparticles can be deposited on the surface of graphene by a simple wet chemical method As silver has a high affinity for sulfur, H2 S gas is readily adsorbed on the Ag surface Although the functionalization of graphene by anchoring AgNPs can theoretically enhance the sensitivity of H2 S gas detection, the weak binding between Ag adatoms and pristine graphene needs to be examined experimentally, revealing that doping with AgNPs enables the structurally-favored H2 S binding Graphene decorated with AgNPs was demonstrated to be an ideal material for the selective and fast H2 S gas sensing and catalytic dissociation of the adsorbed H2 S gas The excellent sensor performance was a result of graphene and Ag energy barrier matching upon contact The graphene H2 S sensor developed in this work exhibited high sensitivity (≤100 ppb), fast response (∼1 s), and a short recovery time (∼20 s) at room temperature The graphene AgNP interface properties were explored by using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and X-ray diffraction (XRD) The action mode of this sensor was ascribed to the charge transfer and band alignment because of the high carrier mobility of graphene and the small energy barrier between graphene and AgNP As a result, the response times were small and both sensitivity and selectivity were quite high Experimental 2.1 Preparation of chemical vapor deposited (CVD) graphene Cu foil was immersed in acetone for 30 and subsequently cleaned in acidic CuSO4 solution (Fig 1A and B) In order to remove copper oxide, the Cu surface was additionally cleaned for 30 in a furnace heated to 1000 ◦ C at 50 mTorr in a flow of H2 (5 sccm, 30 min) Subsequently, a mixture of CH4 and H2 (50:5 sccm) in Ar was passed through the furnace for 30 at 1000 ◦ C to produce a graphene monolayer (Fig 1C) The Cu foil was spin-coated with poly(methyl methacrylate) (PMMA) dissolved in anisole and heated to 100 ◦ C for 15 (Fig 1E) for the next transfer step, followed by etching with 98% ammonium persulfate ((NH4 )2 S2 O8 ) solution Finally, the etched PMMA/graphene was cleaned using deionized water and transferred onto the Si/SiO2 substrates, followed by immersion into acetone for h to remove the PMMA coating (Fig 1F–H) 2.2 Preparation of CVD graphene doped with AgNPs and charged impurities CVD graphene was immersed in a solution containing 34.4 wt% of AgNO3 , wt% of Fe(NO3 )3 ·9H2 O, and 2.8 wt% of 70% HNO3 , and the mixture was stirred for at 20 ◦ C and 1150 rpm The composition of the above solution was optimized by measuring the resistivity and response time of doped graphene in the presence of H2 S Finally, the samples were dried in an oven for h at 100 ◦ C (Fig 1I) 2.3 Characterization of decorated graphene The surface of doped graphene was examined by optical microscopy (Leica DM2700M, Germany), with phase transition Fig Schematic diagram of graphene growth, decoration, and transfer processes Cleaning of Cu foil (A) in acetone and (B) in an electrolyte solution (C) CVD-mediated graphene growth and (D) graphene growth on copper foil (E) Spin-coating of PMMA onto the graphene surface (F) Etching of Cu foil in ammonium persulfate solution (G) Transfer of PMMA/graphene onto the Si/SiO2 substrate after rinsing (H) Removal of PMMA coating in acetone and cleaning of graphene deposited on the silicon wafer with distilled water (I) Soaking of graphene in aqueous AgNO3 and Fe(NO3 )3 at acidic pH with stirring (J) Oven drying of graphene for h at 100 ◦ C analysis carried out using XRD (Dmax2500, Rigaku, Japan) Compositional analysis was performed by XPS (PHI 5000 VersaProbe, Ulvac-PHI, Japan) and SEM (FEI, Inspect F, Oregon, USA) coupled with energy dispersive X-ray spectrometry (EDS) Raman spectra (Reinshaw, Gloucestershire, UK) were recorded in the range of 1300–3000 cm− High resolution images of pristine and doped 280 O Ovsianytskyi et al / Sensors and Actuators B 257 (2018) 278–285 Fig (A) SEM image of pristine graphene (B) SEM image of graphene treated with AgNO3 /Fe(NO3 )3 solution (C) Normalized SEM/EDS spectrum of graphene decorated with AgNPs Fig (A) TEM and (B) HR-TEM image of as prepared graphene decorated with AgNPs (C) Selected area electron diffraction (SAED) pattern for the circled area in (A) graphene were obtained by using a transmission electron microscope (TEM; FEI Talos, Oregon, USA) coupled with EDS 2.4 Gas sensing setup H2 S was mixed with Ar using a gas diluter and further diluted by using an argon balloon (Ar purity: 99.999%) The flow rates of diluted H2 S and Ar were regulated by an in-house built mass flow controller, with the total gas flow rate maintained at L min− In H2 S sensing experiments, the sensor was initially exposed to ambient air to record the baseline resistivity, followed by exposure to H2 S and 25 s purging with air at 60 ◦ C for fast recovery (Table 1) Results and discussion 3.1 Characterization of doped graphene The surface structure and elemental distribution were examined by SEM, which revealed that pristine graphene grown on Cu foil showed a uniform, smooth, and flat surface (Fig 2A), in contrast to doped graphene, for which a large number of 10–100 nm particles uniformly distributed on its surface (Fig 2B) were detected Moreover, EDS elemental mapping confirmed the presence of Ag and Fe (Fig 2C) on the surface of doped graphene AgNPs were formed on graphene by the reduction of Ag+ ions in a solution of AgNO3 and Fe(NO3 )3 at acidic pH, since the reduction potentials ( E) of Ag+ /Ag0 and Fe3+ /Fe0 equal +0.80 and − 0.04 V, ∼ 2.70, G band ∼ Fig Raman spectra of (A) pristine graphene (I2D /IG = = 1588 cm− ) and (B) graphene immersed in a mixed solution of AgNO3 and Fe(NO3 )3 ) for (I2D /IG ∼ = 2.46, G band ∼ = 1592 cm− ) respectively [24] In other words, Fe3+ ions can act as a reducing agent for Ag+ ions due to the difference in their reduction potentials Thus, pristine graphene could be easily doped with AgNPs and charged impurities by a simple wet chemical method The morphology of doped graphene was characterized by TEM, which showed that the AgNPs had a size of 10–30 nm (Fig 3A and B) High resolution (HR)-TEM imaging (Fig 3B) demonstrated that 281 O Ovsianytskyi et al / Sensors and Actuators B 257 (2018) 278–285 Table Comparison of main properties and performance characteristics of nanomaterials used to detect H2 S gas No Sensing material Sensor 10 SnO2 /MWCNTs SnO2 QW/rGO SnO2 QW/rGO Graphene Schottky diode SnO2 –CuO multilayer CuO/SnO2 composite nanofibers ZnO nanorods Single ˇ-AgVO3 nanowire CuO nanowire AgNP-doped graphene Spin coating Spin coating Spin coating Different vacuum and chemical depositions Pulsed laser deposition Electrospinning Hydrothermal Hydrothermal Template-assisted electrodeposition Wet-chemical doping a preparation LODa (ppm) Saturationtime Operation temperature (◦ C) Ref 0.043 0.043 0.075 100 20 0.01 0.1 50 0.01 0.1 23 s 2s 25 s 20 2s 23 s 27 20 s 50 min 70 22 30–70 25 140 200 25 250 180 25 [5] [6] [7] [8] [39] [40] [41] [42] [43] This work LOD, limit of detection Fig (A) Wide scan XPS spectra of pristine graphene (blue line) and graphene doped with AgNPs and charged impurities (black line) (B) High resolution Fe 2p XPS spectrum for binding energies of 706–717 eV (C) High resolution Ag 3d XPS spectrum for binding energies of 365–376 eV (D) XRD spectra of pristine graphene (black line) and graphene soaked in 34.4 wt% AgNO3 + wt% Fe(NO3 )3 solution (red line) (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) most lattice fringes corresponded to (111) and (200) Ag nanocrystal planes with spacings of 0.23 and 0.2 nm, respectively, confirming that the surface of graphene was doped with AgNPs The selected area diffraction (SAED) pattern of polycrystalline rings (Fig 3C) revealed the nanocrystalline structure of composite AgNPs with a small amount of Fe impurities Raman spectroscopy is one of the most sensitive techniques for characterizing disordered sp2 carbon in graphene When scruti- nized closely, the subtle differences between pristine and doped graphene provided important information on their physical properties As both G and 2D bands are strongly influenced by the charge carrier concentration, they are typically considered for characterization of doped materials [28] Fig shows the Raman spectra of pristine and doped graphene, with the D band (∼1345 cm− ) of the former indicating a slight disorder The sharp peak at ∼1585 cm− corresponds to the G band, which involves in-plane vibrations of sp2 282 O Ovsianytskyi et al / Sensors and Actuators B 257 (2018) 278–285 carbons Furthermore, the intensity of this band is highly sensitive to the number of layers present in the sample, and its exact position is affected by doping As the difference in band positions for pristine (1588 cm− ) and doped (1592 cm− ) graphene equaled ∼4 cm− , it confirmed that its immersion into a mixed salt solution resulted in doping It is known that the Raman shift increases concomitantly with the concentration of holes [28] All sp2 carbon materials exhibited a strong peak in the range of 2500–2800 cm− , which corresponded to the 2D band (∼2680 cm− ) caused by electronic band splitting in single layer graphene [29–32] The increased intensity of the upshifted and softened G band in the doped sample implied p-type doping [33] The ratio of 2D and G band intensities (I2D /IG ) for pristine and doped graphene equaled 2.70 and 2.46, respectively, corresponding to monolayer graphene [32,34] Thus, the decrease in the I2D /IG ratio after deposition of AgNPs on graphene implied that doping had taken place The XPS spectra of pristine and doped graphene are shown in Fig 5A–C The high resolution spectrum of doped graphene suggests that AgNPs and charged impurities are uniformly distributed throughout the sample Additionally, prominent Ag 3d and Fe 2p peaks cab be observed for doped graphene, with Fe present in the form of FeO (709.8 eV), Fe2 O3 (711.4 eV), and FeOOH (713.3 eV) (Fig 5B), and Ag present as metallic Ag (368.3 and 374.4 eV), AgO (367.3 eV), and Ag2 O (373.3 eV) (Fig 5C) The XRD patterns recorded for the surface of doped graphene (Fig 5D) and the Miller indices (111, 200, 220, 311, and 222) of the observed peaks clearly indicated the presence of crystalline AgNPs Moreover, an additional (220) peak revealed the presence of a small amount of a charged Fe impurity in one crystallographic orientation It was concluded that these AgNPs were anchored on the surface of graphene, since the Ag C O peak could be clearly observed in the energy range of the C 1s signal in the high-resolution XPS spectrum (not shown) 3.2 H2 S sensing properties of AgNP doped graphene The adsorption of oxygen and water vapor on the surface of graphene under ambient conditions leads to p-type doping because of free electron trapping [35] In view of the high H2 S affinity to Ag and Fe compounds, the mechanism of H2 S sensing by doped graphene can be described in terms of the core adsorption sites provided by the graphene dopants [34,36] Upon interaction with dopants on the surface of graphene, H2 S molecules are cleaved by the metal nanoparticles acting as catalysts, concomitant with the adsorption of oxygen ions This dissociation of H2 S molecules changes the concentration of the charge carriers in the graphene sensor Since the doped graphene used herein was a p-type semiconductor, the release of free electrons reduced the number of holes because of charge recombination, thus increasing resistivity The sensing mechanism can be described by the following steps [36,37]: O2 (gas) → O2 (ads) − Fig (A) Relative resistivity responses of pristine graphene (–), graphene doped with Fe(NO3 )3 solution (–), graphene doped with AgNO3 solution (–), and graphene doped with mixed Fe(NO3 )3 and AgNO3 solution (–) in the presence of 500 ppb of H2 S gas (B) Resistivity response curve for various H2 S concentrations at room temperature for graphene doped with a solution of Fe(NO3 )3 and AgNO3 (C) Relative resistivity response of doped graphene as a function of H2 S concentration − (1) O2 (ads) + e → O2 (ads) (2) 2H2 S + 3O2 − (ads) → 2H2 O ↑ + 2SO2 ↑ + 3e− (3) Exposure of the sensor to an oxidizing gas (e.g., O2 ) triggers Reaction (2) As described earlier, O2 acts as a charge acceptor, removing electrons from the surface of graphene and thus decreasing its resistance When the surface is exposed to H2 S, the adsorption of the gas likely initiates because of its interaction with the adsorbed oxygen species on Ag and not C, as the former is less electronegative than the latter The adsorption of H2 S results in its eventual dissociation, and SO2 and H2 O are formed with the release of electrons These released electrons are fed back into O Ovsianytskyi et al / Sensors and Actuators B 257 (2018) 278–285 283 Scheme Schematic representation of (A) H2 S sensing by graphene decorated with AgNO3 and (B) dissociation of H2 S adsorbed on the surface of decorated graphene EC : conduction band energy, EV : valence band energy, Bg: band gap Fig Response of graphene sensor for various concentrations of (A) CH4 (B) CO2 , (C) O2 , and (D) N2 gas graphene, where they recombine with intrinsic holes This phenomenon decreases the charge carrier concentration, and results in an increase in the resistance of Ag-doped graphene (Scheme 1) Doping of semiconductors is usually achieved by incorporating appropriate atoms into the host lattice of the semiconductor to generate positive charge carriers-holes-in the semiconductor When the dopants are distributed inhomogeneously in the semiconduc- 284 O Ovsianytskyi et al / Sensors and Actuators B 257 (2018) 278–285 repeatability, which were ∼3.48, ∼2.89, and ∼4.58% for 0.5, 1.0, and 5.0 ppm concentration of H2 S gas, respectively Sensor selectivity was also tested using different gases, with the corresponding responses (Fig 7) revealing excellent selectivity for H2 S in the presence of CH4 , CO2 , N2 , and O2 that are typically generated during biogas production For example, sensor responses of 0.65, 0.55, and 0.50% were observed for 100, 75, and 50% of CH4 , respectively, with responses for 50 and 25% CO2 equaling 0.70 and 0.55%, respectively Moreover, 100% O2 and 10% of N2 did not give rise to any visible change in the electrical properties of the sensor In other words, CH4 , CO2 , O2 , and N2 gases produced only negligible sensor responses, implying that other gases present in high concentrations would not interfere with H2 S quantitation using the developed graphene sensor (Fig S2) The relative resistivity responses were measured using 10 ppm of H2 S to test the long-term stability of this sensor, which was found to be very stable in the range of ±3% for at least weeks (not shown) 3.4 Fabrication and testing of a chemiresistive graphene based sensor Fig (A) Schematic representation of the chemiresistive graphene sensor (B) Schematic experimental setup for H2 S gas sensing (VersaSTAT 3; potentiostat/galvanostat) tor lattice, mobile charge carriers are produced and the electric field acts on them [38] Thus, inhomogeneous doping results in local variations of hole concentrations The response of the sensor toward 500 ppb of H2 S was tested as a function of graphene immersion time (Fig S1), revealing that optimum sensing was achieved after of immersion Apparently, these four minutes are sufficient for inhomogeneous doping to proliferate the charge carriers 3.3 Sensitivity and selectivity of H2 S detection Fig 6A illustrates the relative responses of pristine graphene (reference response), graphene doped with Fe(NO3 )3 solution, graphene doped with AgNO3 solution, and graphene doped with a mixed AgNO3 /Fe(NO3 )3 solution to 500 ppb of H2 S After 400 s of exposure time to H2 S, the relative responses of graphene doped with sole Fe(NO3 )3 and AgNO3 solutions increased to ∼1.5 and 5% compared to that of pristine graphene, respectively The relative response of AgNO3 –doped graphene seemed to be slightly better than that of Fe(NO3 )3 –doped graphene, since Ag can provide more favorable H2 S adsorption sites compared to Fe After 360 s of exposure to H2 S, the relative responses of graphene doped with the mixed solution increased dramatically to ∼37% in comparison with that of pristine graphene Additionally, such hybrid composite doping resulted in a very fast recovery time upon hot air purging Fig 6B represents the sensor response as a function of H2 S concentration, with the relative response measuring time set to ∼350 s for each concentration The prepared sensor showed excellent relative responses and response linearity (10, 21, 37, 53, 65, and 137% at 0.1, 0.2, 0.5, 1.0, 5.0, 10, and 50 ppm of H2 S, respectively), as shown in Fig 6C Furthermore, the relative responses were measured four times at three different concentrations of H2 S gas (not shown) These experiments showed good The graphene sensor, built as a chemiresistor because of the high sensitivity and simplicity of this design, was comprised of doped graphene on a SiO2 /Si substrate, which acted as a sensing material bridging the gap between the two silver electrodes The sensor was mounted on a plastic framework, with silver electrodes connecting graphene with the electrical resistance measurement system Two in-house built electrodes were used instead of sputtering an interdigitated transducer array using costly photolithography equipment The fabricated chemiresistive graphene sensor system is displayed in Fig 8A, with a schematic setup for H2 S quantitation presented in Fig 8B The sensor assembly was placed into a sealed glass flask with a gas inlet/outlet (Fig 8B) and connected to a potentiostat/galvanostat (VersaSTAT 3, Ametec Inc., Berwyn, PA, USA) interfaced with a personal computer The inherent resistance of a chemiresistor can be modulated by exposure to the analyte gas, because it is proportional to the concentration of the gas molecules Hence, the concentration of H2 S was quantified by measuring the change in relative resistivity as a function of time The relative sensor response (R) was expressed as a percentage: R (%) = (Rr − Ri )/Ri × 100%, where Rr is the maximum sensor resistivity measured in the presence of H2 S, and Ri is the initial sensor resistivity in the absence of the analyte Conclusion Single layer CVD graphene was treated with a solution of AgNO3 and Fe(NO3 )3 , resulting in doping with AgNPs and a number of charged impurities These dopants generated H2 S adsorption and dissociation sites on the surface of graphene, allowing us to monitor H2 S concentration in real time and achieving an immediate response at ambient temperature Thus, doped graphene was used to fabricate a more sensitive and selective H2 S sensor compared to that produced using pristine graphene The change in the resistance of doped graphene, R = 37%, observed for 350 s exposure to 500 ppb H2 S revealed that H2 S concentrations much lower than 100 ppb could be measured in the presence of other gases if the standard H2 S gas could be diluted to levels below 100 ppb Currently, further optimization of the composition and deposition of nanocomposite graphene dopants is in progress O Ovsianytskyi et al / Sensors and Actuators B 257 (2018) 278–285 Acknowledgments This research was financially supported by the Korea Institute of Science and Technology (2E27070 and 2E27080), and Korea Ministry of Environment (2016000160008) as a “Public Technology Program Based on Environmental Policy” Appendix A Supplementary data Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.snb.2017.10.128 References [1] J Kang, F Huo, P Ning, X Meng, J Chao, C Yin, Two red-emission single and double ‘arms’ fluorescent materials stemmed from ‘one-pot’ reaction for hydrogen sulfide vivo imaging, Sens Actuators B 250 (2017) 342–350 [2] F Huo, Y Zhang, P Ning, X Meng, C Yin, A novel isophorone-based red-emitting fluorescent probe for selective detection of sulfide anions in water for in vivo imaging, J Mater Chem B (2017) 2798–2803 [3] J Li, C Yin, F Huo, Chromogenic and fluorogenic chemosensors for hydrogen sulfide: review of detection mechanisms since the year 2009, RSC Adv (2015) 2191–2206 [4] M MalekAlaiea, M Jahangiri, A.M Rashidib, A HaghighiAsl, N Izadi, Selective hydrogen sulfide (H2 S) sensors based on molybdenum trioxide (MoO3 ) nanoparticle decorated reduced graphene oxide, Mater Sci Semicond Process 38 (2015) 93–100 [5] H Liu, W Zhang, H Yu, L Gao, Z Song, S Xu, M Li, Y Wang, H Song, J Tang, Solution-processed gas sensors employing SnO2 quantum dot/MWCNT nanocomposites, ACS Appl Mater Interfaces (2016) 840–846 [6] Z Song, Z Wei, B Wang, Z Luo, S Xu, W Zhang, H Yu, M Li, Z Huang, J Zang, F Yi, H Liu, Sensitive room-temperature H2 S gas sensors employing SnO2 quantum wire/reduced graphene oxide nanocomposites, Chem Mater 28 (2016) 1205–1212 [7] Z Song, J Liu, Q Liu, H Yu, W Zhang, Y Wang, Z Huang, J Zang, H Liu, Enhanced H2 S gas sensing properties based on SnO2 quantum wire/reduced graphene oxide nanocomposites: equilibrium and kinetics modeling, Sens Actuators B 249 (2017) 632–638 [8] A Fattah, S Khatami, Selective H2 S gas sensing with a graphene/n-Si Schottky diode, IEEE Sens J 14 (2014) 4104–4108 [9] Y.-H Zhang, Y.-B Chen, K.-G Zhou, C.-H Liu, J Zeng, H.-L Zhang, Y Peng, Improving gas sensing properties of graphene by introducing dopants and defects: a first-principles study, Nanotechnology 20 (2009) 185504 [10] S.S Varghese, S Lonkar, K.K Singh, S Swaminathan, A Abdala, Recent advances in graphene based gas sensors, Sens Actuators B 218 (2015) 160–183 [11] A.H Reshak, S Auluck, Adsorbing H2 S onto a single graphene sheet: a possible gas sensor, J Appl Phys 116 (2014) 103702 [12] R.J Toh, H.L Poh, Z Sofer, M Pumera, Transition metal (Mn, Fe Co, Ni)-doped graphene hybrids for electrocatalysis, Chem Asian J (2013) 1295–1300 [13] H Zhang, X Luo, H Song, X Lin, X Lu, Y Tang, DFT study of adsorption and dissociation behavior of H2 S on Fe-doped graphene, Appl Surf Sci 317 (2014) 511–516 [14] Y.-H Zhang, L.-F Han, Y.-H Xiao, D.-Z Jia, Z.-H Guo, F Li, Understanding dopant and defect effect on H2 S sensing performances of graphene: a first-principles study, Comput Mater Sci 69 (2013) 222–228 [15] V Chakrapani, J.C Angus, A.B Anderson, S.D Wolter, B.R Stoner, G.U Sumanasekera, Charge transfer equilibria between diamond and an aqueous oxygen electrochemical redox couple, Science 318 (2007) 1424–1430 [16] J Ristein, Surface transfer doping of semiconductors, Science 313 (2006) 1057–1058 [17] F Maier, M Riedel, B Mantel, J Ristein, L Ley, Origin of surface conductivity in diamond, Phys Rev Lett 85 (2000) 3472–3475 [18] H Liu, Y Liu, D Zhu, Chemical doping of graphene, J Mater Chem 21 (2011) 3335–3345 [19] F Schedin, A.K Geim, S.V Morozov, E.W Hill, P Blake, M.I Katsnelson, K.S Novoselov, Detection of individual gas molecules adsorbed on graphene, Nat Mater (2007) 652–655 [20] Y Song, W Fang, A.L Hsu, J Kong, Iron(III) chloride doping of CVD graphene, Nanotechnology 25 (2014) 395701 [21] Z Jiang, J Li, H Aslan, Q Li, Y Li, M Chen, Y Huang, J.P Froning, M Otyepka, R Zboril, F Besenbacherb, M Dong, A high efficiency H2 S gas sensor material: paper like Fe2 O3 /graphene nanosheets and structural alignment dependency of device efficiency, J Mater Chem A (2014) 6714–6717 [22] K.S Yoo, S.D Han, H.G Moon, S.-J Yoon, C.-Y Kang, Highly sensitive H2 S sensor based on the metal-catalyzed SnO2 nanocolumns fabricated by glancing angle deposition, Sensors 15 (2015) 15468–15477 [23] J.-W Yoon, Y.J Hong, Y.C Kang, J.-H Lee, High performance chemiresistive H2 S sensors using Ag-loaded SnO2 yolk–shell nanostructures, RSC Adv (2014) 16067–16074 285 [24] Y Wang, Y Wang, J Cao, F Kong, H Xia, J Zhang, B Zhu, S Wang, S Wu, Low-temperature H2 S sensors based on Ag-doped Fe2 O3 nanoparticles, Sens Actuators B 131 (2008) 183–189 [25] K Novoselov, A Geim, S Morozov, D Jiang, Y Zhang, S Dubonos, I Grigorieva, A Firsov, Electric field effect in atomically thin carbon films, Science 306 (2004) 666–669 [26] M.S Dresselhaus, P.T Araujo, Perspectives on the 2010 nobel prize in physics for graphene, ACS Nano (2010) 6297–6302 ˜ [27] E.M Córdoba, J.A Munoz, M.L Blázquez, F González, A Ballester, Leaching of chalcopyrite with ferric ion Part III: effect of redox potential on the silver-catalyzed process, Hydrometallurgy 93 (2008) 97–105 [28] R Beams, L.G Cancado, L Novotny, Raman characterization of defects and dopants in graphene, J Phys.: Condens Matter 27 (2015) 083002 [29] X Li, W Cai, J An, S Kim, J Nah, D Yang, R Piner, A Velamakanni, I Jung, E Tutuc, S.K Banerjee, L Colombo, R.S Ruoff, Large-area synthesis of high-quality and uniform graphene films on copper foils, Science 324 (2009) 1312–1314 [30] B Cho, J Yoon, M.G Hahm, D.H Kim, A.R Kim, Y.H Kahng, S.W Park, Y.J Lee, S.G Park, J.D Kwon, C.S Kim, M Song, Y Jeong, K.S Nam, H.C Ko, Graphene-based gas sensor: metal decoration effect and application to a flexible device, Mater Chem C 27 (2014) 5280–5285 [31] H Liu, Y Liu, D Zhua, Chemical doping of graphene, J Mater Chem 21 (2011) 3335–3345 [32] T Oh, CVD graphene synthesis on copper foils and doping effect by nitric acid, Trans Electr Electron Mater (2013) 246–249 [33] H Liu, Y Liu, D Zhua, Chemical doping of graphene, J Mater Chem 21 (2011) 3335–3345 [34] Y Wang, Y Wang, J Cao, F Kong, H Xia, J Zhang, B Zhu, S Wang, S Wu, Low-temperature H2 S sensors based on Ag-doped ␣-Fe2 O3 nanoparticles, Sens Actuators B 131 (2008) 183–189 [35] C.Y Sung, S.A Hashimi, A McCormick, M Tsapatsis, M Cococcioni, Density functional theory study on the adsorption of H2 S and other Claus process tail gas components on copper- and silver-exchanged Y zeolites, J Phys Chem C 116 (2012) 3561–3575 [36] F.C Fabiani, G Fratesi, G.P Brivio, Adsorption of H2 S, HS, S, and H on a stepped Fe(310) surface, Eur Phys J B 78 (2010) 455–460 [37] V.X Hien, Y.-W Heo, Effects of violet- green-, and red-laser illumination on gas-sensing properties of SnO thin film, Sens Actuators B 228 (2016) 185–191 [38] J Ristein, Surface transfer doping of semiconductors, Science 313 (2006) 1057–1058 [39] M.K Verma, V Gupta, A highly sensitive SnO2 –CuO multilayered sensor structure for detection of H2 S gas, Sens Actuators B 166–167 (2012) 378–385 [40] Y Zhao, X He, J Li, X Gao, J Jia, Porous CuO/SnO2 composite nanofibers fabricated by electrospinning and their H2 S sensing properties, Sens Actuators B 165 (2012) 82–87 [41] C Wang, X Chu, M Wu, Detection of H2 S down to ppb levels at room temperature using sensors based on ZnO nanorods, Sens Actuators B 113 (2006) 320–323 [42] L Mai, L Xu, Q Gao, C Han, B Hu, Y Pi, Single ␤-AgVO3 nanowire H2 S sensor, Nano Lett 10 (2010) 2604–2608 [43] X Li, Y Wang, Y Lei, Z Gu, Highly sensitive H2 S sensor based on template-synthesized CuO nanowires, RSC Adv (2012) 2302–2307 Biographies Ovsianytskyi Oleksandr is currently an MS student studying on the fabrication of chemiresistive graphene sensor and characterization of graphene doped with nanoparticles in Korea Institute of Science and Technology Yun-Sik Nam is a senior research scientist working on fabrication of nanoparticle colorimetric sensor and fluorescence sensors in Korea Institute of Science and Technology His research interests cover analytical chemistry and sensor fabrication on hazardous chemicals Ovsianytskyi Tsymbalenko is currently an MS student studying on the fabrication of chemiresistive graphene sensor and characterization of graphene doped with nanoparticles in Korea Institute of Science and Technology Phan-Thi Lan is currently a Ph.D student studying on fabrication of CVD grown graphene and characterization of metal doped graphene in Korea Institute of Science and Technology Myoung-Woon Moon is a principal researcher working on surface modification, biomaterials, and porous materials in Korea Institute of Science and Technology His research interests cover characterization and modification for surface of thin film Kang-Bong Lee is a principal investigator and a professor in Korea Institute of Science and Technology His current research includes the fabrication of chemiresitive graphene gas sensor and colorimetric nanoparticle sensor  ... CVD graphene Chemiresistive sensor H2 S graphene sensor Graphene doping Silver nanoparticle doping a b s t r a c t Herein, we report a highly sensitive and selective H2 S gas sensor based on graphene. .. dissociation of the adsorbed H2 S gas The excellent sensor performance was a result of graphene and Ag energy barrier matching upon contact The graphene H2 S sensor developed in this work exhibited high... al / Sensors and Actuators B 257 (2018) 278–285 Fig (A) SEM image of pristine graphene (B) SEM image of graphene treated with AgNO3 /Fe(NO3 )3 solution (C) Normalized SEM/EDS spectrum of graphene