A highly sensitive ppb-level H2S gas sensor based on fluorophenoxy-substituted phthalocyanine cobalt/rGO hybrids at room temperature

The peripheral and non-peripheral substitution of 4-trifluoromethylphenoxy groups in the design of gas sensing phthalocyanine cobalt/reduced graphene oxide (rGO) hybrids with two different positions of the substituents was realized. Tetra-α(β)-(4-trifluoromethylphenoxy)phthalocyanine cobalt/reduced graphene oxide (3(4)-cF₃poPcCo/rGO) hybrids were prepared through noncovalent interaction, and were analyzed by FT-IR, UV-vis, TGA and SEM. The gas sensing performance of the cF₃poPcCo/rGO hybrid gas sensors towards ppb hydrogen sulfide (H₂S) was measured at room temperature. The results show that the 4-cF₃poPcCo/rGO sensor has better sensitivity, selectivity and reproducibility than the 3-cF₃poPcCo/rGO sensor, as well as a perfect linear response to the concentration of H₂S. For the 4-cF₃poPcCo/rGO sensor, the response sensitivity to 1 ppm H₂S is as high as 46.58, the response and recovery times are 600 s and 50 s for 1 ppm H₂S, and the detection limit is as low as 11.6 ppb. This is mainly due to the loose and porous structure of the cF₃poPcCo/rGO hybrids, the fact that graphene is an excellent conductive agent, and the fact that the electron-withdrawing capability of the trifluoromethyl group can increase the holes of rGO and PcCo. In addition, through electrochemical impedance spectroscopy (EIS) and I–V curves, and density functional theory, the influence of different positions of the substituents of cF₃poPcCo/rGO on the sensing performance and the sensing mechanism for improving sensitivity were discussed and confirmed in detail.

Highly sensitive gas sensing materials are of great importance for environmental pollution monitoring.     

Ruthenium-decorated vanadium pentoxide for room temperature ammonia sensing

Layer structured vanadium pentoxide (V₂O₅) microparticles were synthesized hydrothermally and successfully decorated by a facile wet chemical route, with ∼10–20 nm sized ruthenium nanoparticles. Both V₂O₅ and ruthenium nanoparticle decorated V₂O₅ (1%Ru@V₂O₅) were investigated for their suitability as resistive gas sensors. It was found that the 1%Ru@V₂O₅ sample showed very high selectivity and sensitivity towards ammonia vapors. The sensitivity measurements were carried out at 30 °C (room temperature), 50 °C and 100 °C. The best results were obtained at room temperature for 1%Ru@V₂O₅. Remarkably as short a response time as 0.52 s @ 130 ppm and as low as 9.39 s @ 10 ppm recovery time at room temperature along with high selectivity towards many gases and vapors have been noted in the 10 to 130 ppm ammonia concentration range. Short response and recovery time, high reproducibility, selectivity and room temperature operation are the main attributes of the 1%Ru@V₂O₅ sensor. Higher sensitivity of 1%Ru@V₂O₅ compared to V₂O₅ has been explained and is due to dissociation of atmospheric water molecules on 1%Ru@V₂O₅ as compared to bare V₂O₅ which makes hydrogen atoms available on Brønsted sites for ammonia adsorption and sensing. The presence of ruthenium with a thin layer of oxide is clear from X-ray photoelectron spectroscopy and that of water molecules from Fourier transform infrared spectroscopy.

Layer structured vanadium pentoxide (V₂O₅) microparticles were synthesized hydrothermally and successfully decorated by a facile wet chemical route, with ∼10–20 nm sized ruthenium nanoparticles.     

Boron-doped few-layer graphene nanosheet gas sensor for enhanced ammonia sensing at room temperature

Heteroatom doping in graphene is now a practiced way to alter its electronic and chemical properties to design a highly-efficient gas sensor for practical applications. In this series, here we propose boron-doped few-layer graphene for enhanced ammonia gas sensing, which could be a potential candidate for designing a sensing device. A facile approach has been used for synthesizing boron-doped few-layer graphene (BFLGr) by using a low-pressure chemical vapor deposition (LPCVD) method. Further, Raman spectroscopy has been performed to confirm the formation of graphene and XPS and FESEM characterization were carried out to validate the boron doping in the graphene lattice. To fabricate the gas sensing device, an Si/SiO₂ substrate with gold patterned electrodes was used. More remarkably, the BFLGr-based sensor exhibits an extremely quick response for ammonia gas sensing with fast recovery at ambient conditions. Hence, the obtained results for the BFLGr-based gas sensor provide a new platform to design next-generation lightweight and fast gas sensing devices.

A boron-doped few-layer LPCVD graphene sensor is successfully designed and demonstrated for enhanced NH₃ gas sensing applications.     

Aryl fluoride functionalized graphene oxides for excellent room temperature ammonia sensitivity/selectivity

Herein, we report the covalent functionalization of graphene oxide (GO) through ‘‘click’’ reaction and its applications towards ammonia sensing. This inimitable method of covalent functionalization involves linking GO with azide moiety and click coupling of different derivatives of aryl propargyl ether, which enhances the sensitivity towards ammonia. The functionalized GO were characterized using NMR, XRD, SEM, FT-IR, Raman, UV-Vis, TGA and DSC. Compared to pristine GO, the GO functionalized with Ar samples (GO-Ar) exhibit excellent room temperature ammonia sensing properties with good response/recovery characteristics. It has been observed that 2,3-difluoro and 2,3,4-trifluoro substituted aryl propargyl ether functionalized GO (GO-Ar2 and GO-Ar3) shows superior ammonia sensing with response/recovery of 63%/∼90% and 60%/100%, respectively at 20 ppm. The GO-Ar3 exhibits high sensitivity towards ammonia at 20–100 ppm. Computational studies supports the high sensitivity of GO-Ar towards ammonia due to its high adsorption energy.

Covalent functionalization of graphene oxide (GO) through ‘‘click’’ reaction and its applications towards ammonia sensing has been demonstrated.     

Correction: Boron-doped few-layer graphene nanosheet gas sensor for enhanced ammonia sensing at room temperature

Correction for ‘Boron-doped few-layer graphene nanosheet gas sensor for enhanced ammonia sensing at room temperature’ by Shubhda Srivastava et al., RSC Adv., 2020, 10, 1007–1014. DOI: 10.1039/C9RA08707A

The authors regret that affiliation b was incorrectly provided as Academy of Scientific and Innovative Research (AcSIR), CSIR-National Physical Laboratory Campus, Dr K S Krishnan Road, New Delhi 110012, India.The correct details are provided in the Affiliations section of this document.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Reversible ammonia uptake at room temperature in a robust and tunable metal–organic framework

Ammonia is useful for the production of fertilizers and chemicals for modern technology, but its high toxicity and corrosiveness are harmful to the environment and human health. Here, we report the recyclable and tunable ammonia adsorption using a robust imidazolium-based MOF (JCM-1) that uptakes 5.7 mmol g⁻¹ of NH₃ at 298 K reversibly without structural deformation. Furthermore, a simple substitution of NO₃⁻ with Cl⁻ in a post-synthetic manner leads to an increase in the NH₃ uptake capacity of JCM-1(Cl⁻) up to 7.2 mmol g⁻¹.

Recyclable and tunable ammonia adsorption with JCM-1 and JCM-1(Cl⁻) at room temperature occurs reversibly without structural decomposition.     

A novel one-step synthesis of Ce/Mn/Fe mixed metal oxide nanocomposites for oxidative removal of hydrogen sulfide at room temperature

In this study, CeO₂/Fe₂O₃, CeO₂/Mn₂O₃, and CeO₂/Mn₂O₃/Fe₂O₃ nanocomposites were synthesized by the calcination of molten salt solutions. The microscopic images confirmed polyhedral nanocrystals of 10–20 nm size, clustered to form nanospheres. The elemental mapping confirmed the uniform distribution of transition metal oxides in the CeO₂ matrix. The X-ray diffraction analysis confirmed the phase purity of metal oxides in nanocomposites. The surface area of nanocomposites was in the range of 16–21 m² g⁻¹. X-ray photoelectron spectroscopy confirmed 25–28% of Ce³⁺ ions in the CeO₂ of nanocomposites. These nanocomposites were tested for the removal of hydrogen sulfide gas at room temperature. The maximum adsorption capacity of 28.3 mg g⁻¹ was recorded for CeO₂/Mn₂O₃/Fe₂O₃ with 500 ppm of H₂S gas and 0.2 L min⁻¹ of flow rate. The adsorption mechanism probed by X-ray photoelectron spectroscopy showed the presence of sulfate as the only species formed from the oxidation of H₂S, which was further confirmed by ion chromatography. Thus, the study reports room-temperature oxidation of H₂S over mixed metal composites, which were synthesized by a novel one-step approach.

In this study, CeO₂/Fe₂O₃, CeO₂/Mn₂O₃, and CeO₂/Mn₂O₃/Fe₂O₃ nanocomposites were synthesized by the calcination of molten salt solutions.     

Expanded graphite/NiAl layered double hydroxide nanowires for ultra-sensitive,ultra-low detection limits and selective NOx gas detection at room temperature

To develop an ultra-sensitive and selective NO_x gas sensor with an ultra-low detection limit, expanded graphite/NiAl layered double hydroxide (EG/NA) nanowires were synthesized by using hydrothermal method with EG as a template and adjusting the amount of urea in the reaction. X-ray diffraction and transmission electron microscopy showed EG/NA3 nanowires with a diameter of 5–10 nm and a length greater than 100 nm uniformly dispersed on the expanded graphite nanosheet (>8 layers). The synergy between NiAl layered double hydroxide (NiAl-LDH) and expanded graphite (EG) improved the gas sensing properties of the composites. As expected, gas sensing tests showed that EG/NA composites have superior performance over pristine NiAl-LDH. In particular, the EG/NA3 nanowire material exhibited an ultra-high response (R_a/R_g = 17.65) with ultra-fast response time (about 2 s) to 100 ppm NO_x, an ultra-low detection limit (10 ppb) and good selectivity at room temperature (RT, 24 ± 2 °C), which could meet a variety of application needs. Furthermore, the enhancement of the sensing response was attributed to the nanowire structure formed by NiAl-LDH in the EG interlayer and the conductive nanonetwork of interwoven nanowires.

Expanded graphite/NiAl-LDH nanowires for ultra-sensitive, ultra-low detection limits and selective NO_x gas detection at room temperature.     

Nanostructured WO3/graphene composites for sensing NOx at room temperature

WO₃ has emerged as an outstanding nanomaterial composite for gas sensing applications. In this paper, we report the synthesis of WO₃ using two different capping agents, namely, oxalic acid and citric acid, along with cetyltrimethyl ammonium bromide (CTAB). The effect of capping agent on the morphology of WO₃ material was investigated and presented. The WO₃ materials were characterized using X-ray diffraction analysis (XRD), field emission transmission electron microscopy (FETEM), field emission scanning electron microscopy (FESEM), particle size distribution (PSD) analysis, and UV-visible spectroscopic analysis. WO₃ synthesized using oxalic acid exhibited orthorhombic phase with crystallite size of 10 nm, while WO₃ obtained using citric acid shows monoclinic phase with crystallite size of 20 nm. WO₃ obtained using both capping agents were used to study their gas sensing characteristics, particularly for NO_x gas. The cross sensitivity towards interfering gases and organic vapors such as acetone, ethanol, methanol and triethylamine (TEA) was monitored and explained. Furthermore, the composites of WO₃ were prepared with graphene by physical mixing to improve the sensitivity, response and recovery time. The composites were tested for gas sensing at room temperature as well as at 50 °C and 100 °C. The results indicated that the citric acid-assisted WO₃ material exhibits better response towards NO_x sensing when compared with oxalic acid-assisted WO₃. Moreover, the sensitivity of the WO₃/graphene nanocomposite was better than that of the pristine WO₃ material towards NO_x gas. The WO₃ composite prepared using citric acid as capping agent and graphene exhibits sensing response and recovery time of 29 and 24 s, respectively.

WO₃ have been synthesized using two capping agents out of which citric acid assisted WO₃ was found to exhibit better response towards NO_x than WO₃ obtained from oxalic acid. The sensitivity was further enhanced by preparing composite with graphene.     

Rapid synthesis of cesium lead halide perovskite nanocrystals by l-lysine assisted solid-phase reaction at room temperature

Nowadays, there are many ways to obtain cesium lead halide perovskite nanocrystals. In addition to the synthesis methods carried out in solution, the solid-phase synthesis was reported involving grinding and milling. In this paper, we synthesized luminescent CsPbBr₃/Cs₄PbBr₆ perovskite nanocrystals (PNCs) by three solid-phase synthesis methods (grinding, knocking, stirring) using l-lysine as a ligand. This is the first attempt to use an amino acid for assisting the solid phase synthesis of perovskite and to study the difference in the products obtained by the three solid phase synthesis methods. The results show that the productivity of the solid-phase synthesis methods can be greatly improved by adding l-lysine and the perovskites obtained by the methods are more resistant to water due to the addition of l-lysine. The simplicity of the synthesis process expanded the use of solid-phase synthesis to obtain more perovskites and provided potential applications of perovskite in analytical detection and sensing in aqueous solution.

By comparing three different solid-phase reactions of perovskite powder synthesized using lysine, the reaction process and properties were studied.     

A high-sensitive room temperature gas sensor based on cobalt phthalocyanines and reduced graphene oxide nanohybrids for the ppb-levels of ammonia detection

Highly sensitive gas sensing materials are of great importance for environmental pollution monitoring. In this study, four nanohybrid materials containing different phenoxyl substituents of cobalt phthalocyanines (tetra-β-carboxylphenoxylphthalocyanine cobalt (cpoPcCo), tetra-β-(4-carboxy-3-methoxyphenoxy)phthalocyanine cobalt (cmpoPcCo), tetra-β-phenoxylphthalocyanine cobalt (poPcCo), and tetra-β-(3-methoxyphenoxy)phthalocyanine cobalt (mpoPcCo)) and reduced graphene oxide (rGO) (RPcCo/rGO) were synthesized via non-covalent interactions as a high performance gas sensing materials for the ppb-level detection of ammonia (NH₃). Various characterization techniques, including FT-IR, Raman, UV-vis, TGA, XPS and SEM, were used to confirm the structure, element information and morphology of the as-synthesized materials. The obtained materials were used in interdigital electrodes to fabricate the sensing device, and the gas sensing performance was investigated at room temperature. The obtained sensors exhibited excellent sensitivity, selectivity, good reproducibility and perfect response–concentration linearity towards NH₃, which are mainly ascribed to the synergetic effects of RPcCo and rGO due to the specific surface area structure for NH₃ diffusion, the abundant active sites to adsorb NH₃, and excellent conductivity for efficient electron transport, particularly the effect of RPcCo. For example, the cpoPcCo/rGO-based sensor showed a higher and faster response for low concentration of NH₃ (∼2.5 and 45 s for 100 ppb of NH₃), a ppb level detection and superior stability over 60 days. Besides, the effect of different phenoxyl substituents of cobalt phthalocyanines on the sensing performance and the sensing mechanism for the sensitivity enhancement were discussed and confirmed by the first-principles density functional theory calculations and electrochemical impedance spectroscopy (EIS).

Highly sensitive gas sensing materials are of great importance for environmental pollution monitoring.     

Correction: Gas sensing performance at room temperature of nanogap interdigitated electrodes for detection of acetone at low concentration

Correction for ‘Gas sensing performance at room temperature of nanogap interdigitated electrodes for detection of acetone at low concentration’ by Q. Nguyen Minh et al., RSC Adv., 2017, 7, 50279–50286.

The authors regret that in the original article the authorship was incorrect. J. Baggerman and S. P. Pujari were not included in the original author list. Additionally, J. F. van der Bent was spelled incorrectly in the original article. The correct author list is as presented above.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Porous 3D flower-like CoAl-LDH nanocomposite with excellent performance for NO2 detection at room temperature

The 3D flower-like CoAl-layered double hydroxide (CoAl-LDH) was successfully prepared using the functional template agent of fluoride ions via a facile one-step hydrothermal route. Various techniques proved that all the samples presented 3D flower-like microstructural morphology. Representatively, the CA-2 sample, which was synthesized with the molar ratio of Co : Al of 3.65 : 1, had considerably abundant pores in its thin nanosheets. The average pore size was 2–4 nm, the specific surface area was equal to 49.45 m² g⁻¹, and the thickness of nanosheets was approximately 3.068 nm. The CA-2 sample showed an excellent response to 0.01–100 ppm NO₂ with ultrafast response/recovery time at room temperature (RT). The detection limit of the sensor even reached 10 ppb. The superior gas sensing performance could be attributed to the synergistic effects of the functional template agent of fluoride ions and specific porous 3D flower-like nanostructure. The current study showed that the 3D flower-like CoAl-LDHs might a promising material in practical detection of NO₂ at RT.

We have synthesized 3D flower-like CoAl-LDHs consisting of ultrathin nanosheets for excellent performance for NO₂ detection at room temperature.     

Controlled preparation of multiple mesoporous CoAl-LDHs nanosheets for the high performance of NOx detection at room temperature

By fine tuning the metal mole ratio, CoAl-LDHs (CA) with a 2D nanosheet structure were successfully prepared via a one-step hydrothermal method using urea as both precipitator and pore-forming agent. The morphology of CA samples shows uniform and thin porous hexagonal nanosheets. In particular, CA2-1, prepared with the 2 : 1 molar ratio for Co and Al, respectively, has the highest surface area (54 m² g⁻¹); its average transverse size of platelets is 2.54 μm with a thickness of around 19.30 nm and inter-plate spacing of about 0.2 μm. The sample exhibits a high sensing performance (response value of 17.09) towards 100 ppm NO_x, fast response time (4.27 s) and a low limit of detection (down to 0.01 ppm) at room temperature. Furthermore, CA2-1 shows long -term stability (60 days) and a better selectivity towards NO_x at room temperature. The excellent performance of the fabricated sensor is attributed to the special hexagonal structure of the 2D thin nanosheets with abundant mesopores, where the active sites provide fast adsorption and transportation channels, promote oxygen chemisorption, and eventually decrease the diffusion energy barrier for NO_x molecules. Furthermore, hydrogen bonds between water molecules and OH⁻ could serve as a bridge, thus providing a channel for rapid electron transfer. This easy synthetic approach and good gas sensing performance allow CoAl-LDHs to be great potential materials in the field of NO_x gas sensing.

By fine tuning the metal mole ratio, CoAl-LDHs (CA) with a 2D nanosheet structure were successfully prepared via a one-step hydrothermal method using urea as both precipitator and pore-forming agent.     

Nanostructured cobalt antimonate: a fast responsive and highly stable sensing material for liquefied petroleum gas detection at room temperature

Herein, cobalt antimonate (CoSb₂O₆) nanospheres were fabricated via the sol–gel spin-coating process and employed as a functional liquefied petroleum gas (LPG) sensor at room temperature (25 °C). The microstructure of the fabricated CoSb₂O₆ thin films (thickness ∼ 250 nm) was analyzed via scanning electron microscopy, which revealed the growth of nanospheres having an average diameter of ∼45 nm. The XRD analysis demonstrated the crystalline nature of CoSb₂O₆ with a crystallite size of ∼27 nm. Finally, the fabricated thin films were investigated as sensors for LPG and carbon dioxide (CO₂) at room temperature (25 °C) and 55% R.H. (relative humidity) with different concentrations in the range of 1000–5000 ppm. The sensing results demonstrated greater variations in the electrical properties of films for the incoming LPG than that of the CO₂ gas adsorption. Furthermore, to ensure the long-term stability of fabricated sensors, they were tested periodically at 10 days interval, spanning a total duration of 60 days. In summary, our fabricated LPG sensor displayed high sensitivity (1.96), repeatability, quick response time (21 s) and high long-term stability (99%). Therefore, CoSb₂O₆ nanospheres can be functionalized as a potential LPG-sensitive material characterized by high sensitivity, reliability and stability at room temperature.

Modulation in electrical resistance of the sensing layer due to interaction (adsorption and reactions) with LPG.     

Nanoscale tungsten nitride/nitrogen-doped carbon as an efficient non-noble metal catalyst for hydrogen and oxygen recombination at room temperature in nickel–iron batteries

A nanoscale tungsten nitride/nitrogen-doped carbon (WN/NC) catalyst was synthesized through a facile route, and it exhibited efficient catalytic performance for hydrogen and oxygen recombination at room temperature with an average catalytic velocity of 140 μmol h⁻¹ g_cat⁻¹ and long catalytic life of 954 660 s without decay in the catalytic performance. With the WN/NC catalyst, a nickel–iron battery could be sealed and maintenance-free, and it also exhibited low cost; thus, the nickel–iron battery can be used for large-scale energy storage systems in rural/remote areas.

A nickel–iron battery with nanoscale WN/NC catalyst can be used for large-scale energy storage systems in rural/remote areas.     

Assessment of a four hour delay for urine samples stored without preservatives at room temperature for urinalysis

ObjectivesTo determine whether urine storage at room temperature for up to 2 h versus 4 h changes urinalysis results.Design and methodsWe compared the rejection rate at eight different hospital laboratories and concordance of urinalysis results (n = 83; two laboratories) between urines analyzed within 2 h and 4 h after collection.ResultsThe rejection rate at the two hour cutoff was significantly higher as compared to the four hour cutoff. The concordance between urinalysis results was 97–100% between the two and four hour analyses.ConclusionUrine may be stored for up to 4 h at room temperature without significant changes to the urinalysis results.     

Selective detection of methanol vapour from a multicomponent gas mixture using a CNPs/ZnO@ZIF-8 based room temperature solid-state sensor

Methanol vapour is harmful to human health if it is inhaled, swallowed, or absorbed through the skin. Solid-state gas sensors are a promising system for the detection of volatile organic compounds, unfortunately, they can have poor gas selectivity, low sensitivity, an inferior limit of detection (LOD), sensitivity towards humidity, and a need to operate at higher temperatures. A novel solid-state gas sensor was assembled using carbon nanoparticles (CNPs), prepared from a simple pyrolysis reaction, and zinc oxide@zeolitic imidazolate framework-8 nanorods (ZnO@ZIF-8 nanorods), synthesised using a hydrothermal method. The nanomaterials were characterized using scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy Raman spectroscopy, and Fourier transform infrared spectroscopy. The ZnO@ZIF-8 nanorods were inactive as a sensor, the CNPs showed some sensor activity, and the CNPs/ZnO@ZIF-8 nanorod composite performed as a viable solid-state sensor. The mass ratio of ZnO@ZIF-8 nanorods within the CNPs/ZnO@ZIF-8 nanorod composite was varied to investigate selectivity and sensitivity for the detection of ethanol, 2-propanol, acetone, ethyl acetate, chloroform, and methanol vapours. The assembled sensor composed of the CNPs/ZnO@ZIF-8 nanorod composite with a mass ratio of 1.5 : 6 showed improved gas sensing properties in the detection of methanol vapour with a LOD of 60 ppb. The sensor is insensitive to humidity and the methanol vapour sensitivity was found to be 0.51 Ω ppm⁻¹ when detected at room temperature.

Methanol vapour is harmful to human health if it is inhaled, swallowed, or absorbed through the skin.     

Design and development of highly sensitive PEDOT-PSS/AuNP hybrid nanocomposite-based sensor towards room temperature detection of greenhouse methane gas at ppb level

Herein, we present fabrication of a novel methane sensor based on poly (3,4-ethylenedioxythiophene:poly (styrene sulfonic acid)) (p-PEDOT-PSS) and gold nanoparticles (AuNPs) treated with dimethyl sulfoxide (DMSO) and Zonyl using a spin coating technique. The nanocomposite films were further post treated with H₂SO₄ to improve the charge transport mechanism. The structural and morphological features of the composites were analyzed through scanning electronic microscopy, transmission electron microscopy, Fourier transform infra-red spectroscopy, UV-Vis spectroscopy and thermogravimetric analysis. Treatment with organic solvents and post treatment of H₂SO₄ significantly enhances the conductivity of the composite to 1800 S cm⁻¹. The fabricated sensor shows an excellent sensing response, fast response and recovery time along with acceptable selectivity towards methane gas at ppb concentrations. Due to a simple fabrication technique, excellent conductivity, superior sensing performance and improved mechanical properties, the sensor fabricated in this study could potentially be used to detect greenhouse methane gas at low concentrations.

Fabrication of novel methane sensor based on PEDOT-PSS:AuNPs composite treated with DMSO and Zonyl using spin coating technique.     

Effect of a modified 13X zeolite support in Pd-based catalysts for hydrogen oxidation at room temperature

This study investigated the effect of a modified 13X zeolite to Pd/zeolite catalyst on the oxidation of hydrogen to ensure safety from hydrogen leakage. The catalytic activity of Pd/zeolite catalysts was significantly affected by acid treatment of 13X zeolite support and various calcination temperatures (300 °C, 400 °C, 500 °C, 600 °C) of the Pd/zeolite catalyst. To understand the correlation between the activity and physical properties of the catalysts, activity test, XRD, BET, TEM, TPR, and TPO were performed; Pd/13X (400) was shown to have a high catalytic activity, which depended on the dispersion and particle size of palladium. Also, a strong PdH on the catalyst surface was formed, and a high catalytic activity at a low hydrogen concentration was obtained.

This study investigated the effect of a modified 13X zeolite to Pd/zeolite catalyst on the oxidation of hydrogen to ensure safety from hydrogen leakage.