Effect of H2S on the CO2 corrosion of carbon steel in acidic solutions

The objective of this study is to evaluate the effect of low-level hydrogen sulfide (H₂S) on carbon dioxide (CO₂) corrosion of carbon steel in acidic solutions, and to investigate the mechanism of iron sulfide scale formation in CO₂/H₂S environments. Corrosion tests were conducted using 1018 carbon steel in 1 wt.% NaCl solution (25 °C) at pH of 3 and 4, and under atmospheric pressure. The test solution was saturated with flowing gases that change with increasing time from CO₂ (stage 1) to CO₂/100 ppm H₂S (stage 2) and back to CO₂ (stage 3). Corrosion rate and behavior were investigated using linear polarization resistance (LPR) technique. Electrochemical impedance spectroscopy (EIS) and potentiodynamic tests were performed at the end of each stage. The morphology and compositions of surface corrosion products were analyzed using scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that the addition of 100 ppm H₂S to CO₂ induced rapid reduction in the corrosion rate at both pHs 3 and 4. This H₂S inhibition effect is attributed to the formation of thin FeS film (tarnish) on the steel surface that suppressed the anodic dissolution reaction. The study results suggested that the precipitation of iron sulfide as well as iron carbonate film is possible in the acidic solutions due to the local supersaturation in regions immediately above the steel surface, and these films provide corrosion protection in the acidic solutions.     

The performances of higher alcohol synthesis over nickel modified K2CO3/MoS2 catalyst

Ni modified K₂CO₃/MoS₂ catalyst was prepared and the performance of higher alcohol synthesis catalyst was investigated under the conditions: T = 280–340 °C, H₂/CO (molar radio) = 2.0, GHSV = 3000 h^− 1, and P = 10.0 MPa. Compared with conventional K₂CO₃/MoS₂ catalyst, Ni/K₂CO₃/MoS₂ catalyst showed higher activity and higher selectivity to C₂⁺OH. The optimum temperature range was 320–340 °C and the maximum space-time yield (STY) of alcohol 0.30 g/ml h was obtained at 320 °C. The selectivity to hydrocarbons over Ni/K₂CO₃/MoS₂ was higher, however, it was close to that of K₂CO₃/MoS₂ catalyst as the temperature increased. The results indicated that nickel was an efficient promoter to improve the activity and selectivity of K₂CO₃/MoS₂ catalyst.     

Calcination and sintering characteristics of limestone under O2/CO2 combustion atmosphere

The O₂/CO₂ coal combustion technology is an innovative combustion technology that can control CO₂, SO₂ and NO_x emissions simultaneously. Calcination and sintering characteristics of limestone under O₂/CO₂ atmosphere were investigated in this paper. The pore size, the specific pore volume and the specific surface area of CaO calcined were measured by N₂ adsorption method. The grain size of CaO calcined was determined by XRD analysis. The specific pore volume and the specific surface area of CaO calcined in O₂/CO₂ atmosphere are less than that of CaO calcined in air at the same temperature. And the pore diameter of CaO calcined in O₂/CO₂ atmosphere is larger than that in air. The specific pore volume and the specific surface area of CaO calcined in O₂/CO₂ atmosphere increase initially with temperature, and then decline as temperature exceeds 1000 °C. The peaks of the specific pore volume and the specific surface area appear at 1000 °C. The specific surface area decreases with increase in the grain size of CaO calcined. The correlations of the grain size with the specific surface area and the specific pore volume can be expressed as L = 744.67 + 464.64 lg(1 / S) and L = − 608.5 + 1342.42 lg(1 / ε), respectively. Sintering has influence on the pore structure of CaO calcined by means of influencing the grain size of CaO.     

The experiment research of corrosion behaviour about Ni-based alloys in simulant solution containing H2S/CO2

Aimed at the problem of tubing corrosion in environment that containing hydrogen sulfide (H₂S), carbon dioxide (CO₂), and chlorides (Cl⁻), the corrosion behaviour of two nickel based alloys (UNS 06985 and UNS 08825) in 15 wt%NaCl solution containing H₂S/CO₂ in high temperature and high pressure environment was investigated. The pitting corrosion behaviour of Ni-based alloys was studied in FeCl₃·6H₂O solution by means of polarisation curve and immersion tests. The scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) was applied to analyse the microstructure and corrosion performance of the samples. The results showed that the pitting-resistant of nickel alloy UNS 06985 was superior to UNS 08825. With the rising of experimental temperature, the corrosion increased and some slight pitting attacks appeared on the surface of UNS 08825. The test temperature was the crucial factor that influenced not only the compactness and the growing rate of corrosion product scale, but also the corrosion rate of the alloys. Elemental sulfur is a strong oxidant, the presence of S0 leads to a serious localized corrosion. XRD showed that the corrosion films formed on nickel base alloys consisted of NiS, CrO₃, and the oxides of Ni and Fe. The polarisation curves showed a different corrosion behaviour of two alloys, anodic curve of UNS 06985 has a wider passivation area, and there has higher transpassive potential.     

Gasoline-range hydrocarbon synthesis over Co/SiO2/HZSM-5 catalyst with CO2-containing syngas

Selective synthesis of gasoline-range hydrocarbons (C₅-C₁₂) was investigated in a fixed-bed micro reactor using two series of CO₂-containing syngas with various mole CO₂/(CO + CO₂) and H₂/(CO + CO₂) ratios, where Fischer-Tropsch synthesis(FTS) and in situ hydrocracking/hydroisomerization were performed over bifunctional Co/SiO₂/HZSM-5 catalyst. CO₂ was converted at 0.15-0.55 of CO₂/(CO + CO₂) ratio under H₂-rich condition (H₂/(CO + CO₂) = 2.0), highest conversion of 20.3% at 0.42. Further increasing CO₂ content decreased CO₂ conversion and quite amount of CO₂ acted as diluting component. For the syngas with low H₂ content or H₂/(CO + CO₂) ratio(< 1.85, H₂/CO = 2.0), the competitive adsorption of CO, H₂ and CO₂ resulted in low CO, CO₂ and total carbon conversion, which was 57.9%, 12.7% and 31.4% respectively at 0.74 of H₂/(CO + CO₂) ratio(H₂/CO/CO₂/N₂ = 40.8/20.4/34.8/4). FTS results indicated that high H₂ content and proper H₂/(CO + CO₂) ratio were favorable for the conversion of CO₂-containing syngas. More than 45% selectivity to gasoline-range hydrocarbons including isoparaffins was obtained under the two series of syngas. It was also tested that the catalytic activity of Co/SiO₂/HZSM-5 kept stable under CO₂-containing syngas(< 7.5%). And the quick catalytic deactivation under high CO₂ containing syngas(H₂/CO/CO₂/N₂ = 45.3/23.2/27.1/3.06) was due to carbon deposition and pore blockage by heavy hydrocarbon, tested by thermal gravimetry, N₂ physisorption and scanning electron microscopy(SEM).     

油气田CO2/H2S共存腐蚀与缓蚀技术研究进展

CO₂/H₂S是油气田采集、运输、处理过程中主要的腐蚀介质，由其引起的管道设备的腐蚀问题变得越来越严重，腐蚀和防腐已经成为研究热点。分别对近年来国内外开展的有关CO₂和H₂S共存腐蚀及缓蚀技术的研究进行综述。CO₂/H₂S共存腐蚀研究主要依靠试验手段，但目前的研究结果有很大的离散性，根据不同的试验条件会产生不同的研究结果。分压比是国内外大多数学者研究CO₂/H₂S腐蚀规律的切入点，但关于两者主导腐蚀的分压比界限划分现有研究存有争议。缓蚀技术研究讨论了缓蚀剂作用机理，评述了抑制CO₂/H₂S共存腐蚀常用的酰胺类、咪唑啉衍生物类、季铵盐类和Schiff碱类缓性剂在国内外的研究与应用现状，展望了这一领域的研究前景及发展方向。     

Soft template synthesis of mesoporous Co3O4/RuO2·xH2O composites for electrochemical capacitors

Co₃O₄/RuO₂·xH₂O composites with various Ru content (molar content of Ru = 5%, 10%, 20%, 50%) were synthesized by one-step co-precipitation method. The precursors were prepared via adjusting pH of the mixed aqueous solutions of Co(NO₃)₂·6H₂O and RuCl₃·0.5H₂O by using Pluronic123 as a soft template. For the composite with molar ratio of Co:Ru = 1:1 annealed at 200 °C, Brunauer-Emmet-Teller (BET) results indicated that the composite showed mesoporous structure, and the specific surface area of the composite was as high as 107 m² g⁻¹. The electrochemical performances of these composites were measured in 1 M KOH electrolyte. Compared with the composite prepared without template, the composite with P123 exhibited a higher specific capacitance. When the molar content of Ru was rising, the specific capacitance of the composites increased significantly. It was also observed that the crystalline structures as well as the electrochemical activities were strongly dependent on the annealing temperature. A capacitance of 642 F/g was obtained for the composite (Co:Ru = 1:1) annealed at 150 °C. Meanwhile, the composites also exhibited good cycle stability. Besides, the morphologies and textural characteristic of the samples were also investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM).     

Aqueous piperazine derivatives for CO2 capture: Accurate screening by a wetted wall column

Concentrated aqueous piperazine (PZ) has been identified as a better solvent for CO₂ capture than monoethanolamine (MEA), because it has a greater rate of CO₂ absorption and greater CO₂ capacity. This work evaluates the effect of substitute groups on PZ performance. Many previous screening studies measured absorption/desorption with CO₂/N₂ sparging, which lacks accuracy and cannot be used to estimate actual absorber performance. In this work a wetted wall column was used to accurately measure absorption/desorption rate at typical rich and lean CO₂ loading (α) and simulate performance of real packing. The method also provides accurate measurement of CO₂ solubility at 40-100 °C. This study provided rate and solubility data at 40-100 °C and practical ranges of CO₂ loading for 8 m 1-methylpiperazine (1-MPZ), 8 m 2-methylpiperazine (2-MPZ), 4 m 2-MPZ/4 m PZ, 7.7 m N-(2-hydroxyethyl)piperazine (HEP), 6 m 1-(2-aminoethyl)piperazine (AEP), 8 m 2-piperidine ethanol (2-PE), and 2 m trans-2,5-dimethylpiperazine (2,5-DMPZ). With the measurements of CO₂ flux (NCO₂) and equilibrium driving force, liquid film mass transfer coefficients (k_g′) are calculated. The rate decreases as of 1-MPZ = PZ > 2-MPZ/PZ > 2-MPZ > HEP > MEA > AEP = 2-PE. This method also allows bracketing and determination of equilibrium CO₂ partial pressure (^*PCO₂) at each condition. Semi-empirical solubility models of CO₂ for each amine were regressed from experimental solubility data to find the lean and rich CO₂ loading corresponding to 0.500 kPa and 5 kPa CO₂ partial pressure respectively. Based on the solubility model, the actual operating capacity of the solvents without overstripping decreases in the sequence of 2-PE > 2-MPZ > 2-MPZ/PZ > 1-MPZ > PZ > HEP > AEP > MEA. The enthalpy of CO₂ absorption (ΔH_abs) of all the piperazine derivatives is around 70 kJ/mol CO₂.     

Mechanism and kinetics of Al2O3 nanoparticles formation by reaction of bulk Al with H2O and CO2 at sub- and supercritical conditions

Oxidation of bulk samples of 〈Al〉 by water and H₂O/CO₂ mixture at sub- and supercritical conditions for uniform temperature increase and at the injection of H₂O (665 K, 23.1 MPa) and H₂O/CO₂ (723 K, 38.0 MPa) fluids into the reactor has been studied. Transition of 〈Al〉 into AlOOH and Al₂O₃ nanoparticles has been found out. Aluminum samples oxidized by H₂O and H₂O/CO₂ fluids at the injection mostly consist of large particles (300-500 nm) of α-Al₂O₃. Those oxidized for uniform temperature increase contain smaller particles (20-70 nm) of γ-Al₂O₃ as well. Mechanism of this phenomenon is explained by orientation of oxygen in H₂O polar molecules to the metal in the electric field of contact voltage at Al/AlOOH and Al/Al₂O₃ boundary. Addition of CO₂ to water resulted in CO, CH₄, CH₃OH and condensed carbon, increase in size of Al₂O₃ nanoparticles and significant decrease in time delay. In pure CO₂ 〈Al〉 oxidation resulted in oxide film. Using temperature and time dependences of gaseous reactant pressure and Redlich-Kwong state equation, kinetics of H₂ formation has been described and oxidation regularities determined. At aluminum oxidation by H₂O and H₂O/CO₂ fluids, self-heating of the samples followed by oxidation rate increase has been registered. The samples of oxidized aluminum have been studied with a transmission electronic microscope, a thermal analyzer and a device for specific surface measurement. The effect of oxidation conditions on the characteristics of synthesized nanoparticles has been found out.     

Impact of SO2 concentration on the corrosion rate of X70 steel and iron in water-saturated supercritical CO2 mixed with SO2

The corrosion behavior of X70 steel and iron in water-saturated supercritical CO₂ mixed with SO₂ was investigated using weight-loss measurements. As a comparison, the instantaneous corrosion rate in the early stages for iron in the same corrosion environment was measured by resistance relaxation method. Surface analyzes using SEM/EDS, XRD and XPS were applied to study the morphology and chemical composition of the corroded sample surface. Weight-loss method results showed that the corrosion rate of X70 steel samples increased with SO₂ concentration, while the corrosion rate increased before decreasing with SO₂ concentration for iron sample. Comparing resistance relaxation method results with weight-loss method results, it is found that the instantaneous corrosion rate of iron is much higher than the uniform corrosion rate of the iron tablet specimens which are covered with thick corrosion product films after a long period of corrosion. The corrosion product films were mainly composed of FeSO₄ and FeSO₃ hydrates. The possible reaction mechanism under such environment was also analyzed, and the electrochemical reaction between the dissolved SO₂ in the condensed water film with iron is the critical reaction step.     

V-doped In2O3 nanofibers for H2S detection at low temperature

Pristine and vanadium-doped In₂O₃ nanofibers were fabricated by electrospinning and their sensing properties to H₂S gas were studied. X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the inner structure and the surface morphology. The H₂S-sensing performances were characterized at different temperatures ranging from 50 to 170 °C. The sensor based on 6 mol% V-doped In₂O₃ nanofibers exhibit the highest response, i.e. 13.9–50 ppm H₂S at the relatively low temperature of 90 °C. In addition, the fast response (15 s) and recovery (18 s) time, and good selectivity were observed.     

Passivity of OC404 steel modified electrochemically with CeO2-Ce2O3 layers in sulfuric acid media

The effect of cerium oxides film, formed electrochemically on OC404 stainless steel (SS), upon the corrosion behavior of steel in 0.1N H₂SO₄ was investigated. The modification of the steel surface by deposition of cerium oxides films was found to improve the steel corrosion resistance. A linear dependence between the stationary corrosion potential of the cerium oxides/SS system and the cerium concentration in the oxide film was established. The shift of the corrosion potential in the positive direction was found to depend on the proceeding of a depolarizing cathode reaction of CeO₂ reduction (instead of the hydrogen depolarizing reaction) occurring on the cathodic zones, formed by this oxide. On the basis of XPS analyses of the samples, subjected to real corrosion under the conditions of self-dissolution, a pronounced drop of the surface concentration of CeO₂ was established. This is a proof of the occurrence of an effective cathode process of CeO₂ reduction to Ce₂O₃, which was then dissolved in H₂SO₄. Data were obtained (XPS) on the composition and structure of the surface film (SEM) after electrodeposition of cerium oxides and after corrosion in the sulfuric acid medium under consideration for time intervals ranging from 50 up to 1000 h. The ICP-AES studies acquired data on the quantity of dissolved elements, forming the passive layer. After exposure to the corrosive medium, the deposited layer showed enrichment in oxides of chromium and aluminium. The passive film on stainless steel, modified in this way, proved to be more stable to the effect of aggressive sulfuric acid medium, compared to the case of natural passive film.     

High-pressure sorption isotherms and sorption kinetics of CH4 and CO2 on coals

Using a manometric experimental setup, high-pressure sorption measurements with CH₄ and CO₂ were performed on three Chinese coal samples of different rank (VR_r = 0.53%, 1.20%, and 3.86%). The experiments were conducted at 35, 45, and 55 °C with pressures up to 25 MPa on the 0.354-1 mm particle fraction in the dry state. The objective of this study was to explore the accuracy and reproducibility of the manometric method in the pressure and temperature range relevant for potential coalbed methane (CBM) and CO₂-enhanced CBM (CO₂-ECBM) activities (P > 8 MPa, T > 35 °C). Maximum experimental errors were estimated using the Gauss error propagation theorem, and reproducibility tests of the high-pressure sorption measurements for CH₄ and CO₂ were performed. Further, the experimental data presented here was used to explicitly study the CO₂ sorption behaviour of Chinese coal samples in the elevated pressure range (up to 25 MPa) and the effects of temperature on supercritical CO₂ sorption isotherms.The experiments provided characteristic excess sorption isotherms which, in the case of CO₂ exhibit a maximum around the critical pressure and then decline and level out towards a constant value. The results of these manometric tests are consistent with those of previous gravimetric sorption studies and corroborate a crossover of the 35, 45, and 55 °C CO₂ excess sorption isotherms in the high-pressure range. The measurement range could be extended, however, to significantly higher pressures. The excess sorption isotherms tend to converge, indicating that the temperature dependence of CO₂ excess sorption on coals at high-pressures (>20 MPa) becomes marginal. Further, all CO₂ high-pressure isotherms measured in this study were approximated by a three-parameter excess sorption function with special consideration of the density ratio of the “free” phase and the sorbed phase. This function provided a good representation of the experimental data.The maximum excess sorption capacity of the three coal samples for methane ranged from 0.8 to 1.6 mmol/g (dry, ash-free) and increased from medium volatile bituminous to subbituminous to anthracite. The medium volatile bituminous coal also exhibited the lowest overall excess sorption capacity for CO₂. However, the subbituminous coal was found to have the highest CO₂ sorption capacity of the three samples. The mass fraction of adsorbed substance as a function of time recorded during the first pressure step was used to analyze the kinetics of CH₄ and CO₂ sorption on the coal samples. CO₂ sorption proceeds more rapidly than CH₄ sorption on the anthracite and the medium volatile bituminous coal. For the subbituminous coal, methane sorption is initially faster, but during the final stage of the measurement CO₂ sorption approaches the equilibrium value more rapidly than methane.     

Selective oxidation of methanol to dimethoxymethane over acid-modified V2O5/TiO2 catalysts

Selective oxidation of methanol to dimethoxymethane (DMM) was conducted in a fixed-bed reactor over an acid-modified V₂O₅/TiO₂ catalyst. The influence of the acid modification on its structure, redox and acidic properties, and catalytic performance for methanol oxidation were investigated. The results indicated that the content of vanadia in the catalyst exhibits a vital influence on the dispersion of vanadium species, while the acid modification can enhance its surface acidity. Proper amounts of the acid (W() = 15%) and V₂O₅ (W(V₂O₅) = 15%) components loaded in the acid-modified V₂O₅/TiO₂ catalyst are able to build a bi-functional circumstance that is favorable for the formation of DMM with high activity and selectivity. As a result, for the selective oxidation of methanol, the H₂SO₄-modified V₂O₅/TiO₂ catalyst gives a much higher DMM yield at 150 °C than the unmodified one.     

Room temperature magnetoelectric coupling study in multiferroic Bi4NdTi3Fe0.7Ni0.3O15 prepared by a multicalcination procedure

Single-phase Bi₄NdTi₃Fe_0.7Ni_0.3O₁₅ polycrystalline samples were synthesized following a multicalcination procedure. The sample exhibited multiferroic property at room temperature, which was demonstrated by the ferroelectric (2P_r=8.52 μC/cm², 2E_c=89 kV/cm at applied electric field 110 kV/cm) and magnetic (2M_r=388 m emu/g, 2H_c=689 Oe at applied magnetic field 1.04 T) hysteresis loops. More importantly, magnetoelectric coupling effect is observed from measurements of electrical properties not only under small but also under large electric signal when an external magnetic field is applied. The present results suggest a new candidate for a room temperature multiferroic material with magnetoelectric coupling effect.     

Protection of mild steel corrosion with Schiff bases in 0.5 M H2SO4 solution

Three new Schiff bases, viz., N,N′-ethylen-bis (salicylidenimine) [S₁], N,N′-isopropylien-bis (salicylidenimine) [S₂], and N-acetylacetone imine, N′-(2-hydroxybenzophenone imine) ortho-phenylen [S₃] have been investigated as corrosion inhibitors for mild steel in 0.5 M H₂SO₄ using Tafel polarization and electrochemical impedance spectroscopy (EIS). The three Schiff bases function as good inhibitors reaching inhibition efficiencies of ∼97-98% at 300 ppm concentration. The fraction <theta> of the metal surface covered by the inhibitor is found to increase with inhibitor concentration. Of the three Schiff bases, the S2 shows better efficiency than the other two Schiff bases. The adsorption of the inhibitor follows Langmuir isortherm. Thermodynamic calculations indicate the adsorption to be physical in nature.     

Microwave dielectric properties of the (1 − x)Mg2TiO4-xCaTiO3-y wt.% ZnNb2O6 ceramics system

Composite ceramics based on (1 − x)Mg₂TiO₄-xCaTiO₃-y wt.% ZnNb₂O₆ (x = 0.12-0.16, y = 0-8) were prepared by a conventional mixed-oxide route. Zn²⁺ partially replaced Mg²⁺ in Mg₂TiO₄ and formed the spinel-structured (Mg_1−δZn_δ)₂TiO₄ phase. Nb²⁺, is known to be solid soluble in CaTiO₃, was found to change its shape from cubic to pliable. A bi-phase system (Mg_1−δZn_δ)₂TiO₄ and CaTiO₃ exhibited in all samples, where a small amount of second phase Mg_1−δZn_δTiO₃ was also detected. The microwave dielectric properties of specimens were strongly related to ZnNb₂O₆ and CaTiO₃ content. As y increased, ?_r and τ_f decreased, however, Q × f decreased to a minimum value and started to increase thereafter. It was also found that ?_r and τ_f increased and Q × f decreased with increasing x. The optimized microwave dielectric properties with ?_r = 18.37, Q × f = 31,027 GHz (at 6 GHz), and τ_f = 0.51 ppm/°C were achieved for (1 − x)Mg₂TiO₄-xCaTiO₃-y wt.% ZnNb₂O₆ (x = 0.12, y = 4) sintered at 1360 °C for 6 h.     

Enhanced solid-state electrogenerated chemiluminescence of Au/CdS nanocomposite and its sensing to H2O2

Au nanoparticles (AuNPs) are good quenchers once they closely contact with luminophore. Here we reported a simple approach to obtain enhanced electrogenerated chemiluminescence (ECL) behavior based on Au/CdS nanocomposite films by adjusting the amount of AuNPs in the nanocomposite. The maximum enhancement factor of about 4 was obtained at an indium tin oxide (ITO) electrode in the presence of co-reactant H₂O₂. The mechanism of this enhancement was discussed in detail. The strong ECL emission from Au/CdS nanocomposites film was exploited to determine H₂O₂. The resulting ECL biosensors showed a linear response to the concentration of H₂O₂ ranging from 1.0 × 10⁻⁸ to 6.6 × 10⁻⁴ mol L⁻¹ with a detection limit of 5 nmol L⁻¹ (S/N = 3) and good stability and reproducibility.     

An unusual H2O2 electrochemical sensor based on Ni(OH)2 nanoplates grown on Cu substrate

In this work, Ni(OH)₂ nanoplates grown on the Cu substrate were synthesized and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Then a novel Cu-Ni(OH)₂ modified glass carbon electrode (Cu-Ni(OH)₂/GCE) was fabricated and evaluated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and typical amperometric response (i-t) method. Exhilaratingly, the Cu-Ni(OH)₂/GCE shows significant electrocatalytic activity toward the reduction of H₂O₂. At an applied potential of −0.1 V, the sensor produces an ultrahigh sensitivity of 408.1 μA mM⁻¹ with a low detection limit of 1.5 μM (S/N = 3). The response time of the proposed electrode was less than 5 s. What's more, the proposed sensor displays excellent selectivity, good stability, and satisfying repeatability.     

Nanocrystalline In2O3-SnO2 thick films for low-temperature hydrogen sulfide detection

Nanocrystalline In₂O₃-SnO₂ thick films were fabricated using the screen-printing technique and their responses toward low concentrations of H₂S in air (2-150 ppm) were tested at 28-150 °C. The amount of In₂O₃-loading was varied from 0 to 9 wt.% of SnO₂ and superb sensing performance was observed for the sensor loaded with 7 wt.% In₂O₃, which might be attributed to the decreased crystallite size as well as porous microstructure caused by the addition of In₂O₃ to SnO₂ without structural modification. The interfacial barriers between In₂O₃ and SnO₂ might be another major factor. Typically, the response of 7 wt.% In₂O₃-loaded SnO₂ sensor toward 100 ppm of H₂S was 1481 at room temperature and 1921 at optimal operating temperature (40 °C) respectively, and showed fast and recoverable response with good reproducibility when operated at 70 °C, which are highly attractive for the practical application in low-temperature H₂S detection.