• Journal of the Korean Chemical Society
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• v.67 no.6
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• pp.415-419
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• 2023

In this study, we report the one-pot synthesis of reduced graphene oxide (rGO) containing platinum nanoparticles with catalytic activity to break down hydrogen peroxide as a peroxidase-mimicking catalyst. A single reducing agent was used to reduce graphene oxide and a platinum precursor at a moderately low temperature of 70℃. The rGO was homogeneously decorated with platinum nanoparticles. The catalytic activity of Pt-rGO was investigated for the oxidation of 3,3',5,5'- tetramethylbenzidine (TMB), a peroxidase substrate, in the presence of hydrogen peroxide. The Pt-rGO coupled with glucose oxidase was also able to detect glucose at millimolar concentrations (up to 1 mM). Our results show that the Pt-rGO composite is a promising catalyst for the detection of hydrogen peroxide. This method was also applied for the detection of glucose.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.21-30
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• 2006

[ $M/Fe_2O_3$ ] (M=Rh, Ce and Zr) mixed oxides were prepared using urea method to develop a medium for chemical hydrogen storage by their redox cycles. And their redox behaviors by repeated cycles were studied using temperature programmed reaction(TPR) technique. Additives such as Rh, Ce and Zr were added to iron oxides in order to lower the reaction temperature for reduction by hydrogen and re-oxidation by water-splitting. From the results, concentration of urea used as a precipitant had little effect on particle size and reduction property of iron oxide. TPR patterns of iron oxide consisted of two reduction peaks due to the course of $Fe_2O_3\;{\rightarrow}\;Fe_3O_4\;{\rightarrow}\;Fe$. The results of repeated redox tests showed that Rh added to iron oxide have an effect on lowering the re-oxidation temperature by water-splitting. Meanwhile, Ce and Zr additives played an important role in prevention of deactivation by repeated cycles. Finally, Fe-oxide(Rh, Ce, Zr) sample added with Rh, Ce and Zr showed the lowest re-oxidation temperature by water-splitting and maintained high $H_2$ recovery in spite of the repeated redox cycles. Consequently, it is expected that Fe-oxide(Rh, Ce, Zr) sample can be a feasible medium for chemical hydrogen storage using redox cycle of iron oxide.

• Journal of the Korean Ceramic Society
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• v.47 no.1
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• pp.1-7
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• 2010

Solid oxide fuel cells (SOFCs) have been under development for a variety of power generation applications. Power system sizes considered range from small watt-size units (e.g., 50-W portable devices) to very large multi-megawatt systems (e.g., 500-MW base load power plants). Because of the reversibility of its operation, the SOFC has also been developed to operate under reverse or electrolysis mode for hydrogen production from steam (In this case, the cell is referred to as solid oxide electrolysis cell or SOEC.). Potential applications for the SOEC include on-site and large-scale hydrogen production. One critical requirement for practical uses of these systems is long-term performance stability under specified operating conditions. Intrinsic material properties and operating environments can have significant effects on cell performance stability, thus performance degradation rate. This paper discusses potential applications of the SOFC/SOEC, technological status and current research and development (R&D) direction, and certain aspects of long-term performance degradation in the operation of SOFCs/SOECs for power generation/hydrogen production.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.52.1-52.1
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• 2009

Cupric oxide (CuO) is a p-type semiconductor with band gap of ~1.7 eV and reported to be suitable for catalysis, lithium-copper oxide electrochemical cells, and gas sensors applications. The nanoparticles, plates and nanowires of CuO were found sensing to NO2, H2S and CO. In this work, we report about the comparison about hydrogen sensing of nano thin film and nanowires structured CuO deposited on single-walled carbon nanotubes (SWNTs). The thin film and nanowires are synthesized by deposition of Cu on different substrate followed by oxidation process. Nano thin films of CuO are deposited on thermally oxidized silicon substrate, whereas nanowires are synthesized by using a porous thin film of SWNTs as substrate. The hydrogen sensing properties of synthesized materials are investigated. The results showed that nanowires cupric oxide deposited on SWNTs showed higher sensitivity to hydrogen than those of nano thin film CuO did.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.157.2-157.2
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• 2011

In this work, we prepared Mg nanoparticles loaded graphite oxide (Mg-G) as a function of Mg content in order to investigate hydrogen storage behaviors. The structure and morphology of the Mg-G samples were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The textural properties of the samples were evaluated using $N_2$/77 K adsorption isotherms. The hydrogen adsorption capacities were investigated at 298 K/10 MPa. As a result, the hydrogen adsorption capacities of the Mg-G were enhanced with increasing the Mg content. Therefore, it was found that the presence of Mg on graphite surfaces created hydrogen-favorable sites, resulting in enhancing the hydrogen adsorption capacity.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.4
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• pp.329-334
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• 2016

Hydrogen is eco-friendly alternative energy source and the photoelectrochemical water splitting is believed to be one of the promising methods for hydrogen production. Many researchers have studied several potential photocatalysts to increase the photoelectochemical performance efficiency for hydrogen conversion. In this study, the GO (graphene oxide) was prepared by Tour's method and was dispersed in precursor solutions of $WO_3$ and $BiVO_4$. Those precursor solutions were spin-coated on FTO glass and several photocatalyst thin films of $WO_3$, $BiVO_4$ and $WO_3/BiVO_4$ were prepared by calcination. The morphologies of prepared photocatalyst thin films were measured by scanning electron microscope. The photoelectrochemical performances of photocatalyst thin films with rGO (reduced graphene oxide) and without rGO were analyzed systematically.

• Korean Journal of Acupuncture
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• v.28 no.1
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• pp.61-69
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• 2011

Objectives : The purpose of this study is to investigate effects of White Ginseng-Ejung-tang acupuncture solution (EJ) on nitric oxide (NO) and of hydrogen peroxide production in RAW 264.7 mouse macrophages stimulated by lipopolysaccharide (LPS). Methods : Cell viability was measured by modified MTT assay. NO production was measured by Griess reagent assay. Hydrogen peroxide production was measured by dihydrorhodamine 123 (DHR) assay. Significant differences were examined by using a Student's t-test. Results : The results of the experiment are as follows. 1. EJ did not show cell toxicity against RAW 264.7 cells for 24 hr incubation at the concentrations of up to $200\;{\mu}g$/mL in RAW 264.7 cells. 2. EJ significantly inhibited NO production for 24 hr incubation in RAW 264.7 cells (p <0.05). 3. EJ significantly inhibited the LPS-induced production of NO for 24 hr incubation in RAW 264.7 cells (p <0.05). 4. EJ significantly inhibited the LPS-induced production of hydrogen peroxide for 16, 24, 40, 48, 64, and 72 hr incubation in RAW 264.7 cells (p <0.05). Conclusions : These results suggest that EJ has an anti-inflammtory property related with its inhibition of NO and hydrogen peroxide production in LPS-induced macrophages.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.3
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• pp.201-207
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• 2004

Redox characteristics of metal oxide for hydrogen production by thermochemical water-splitting were investigated. $CuFe_2O_4$ as a redox pair that had a different molar ratio of Cu and Fe were prepared by co-precipitation method. Hydrogen production consisted of water-splitting step and thermal reduction step was performed below 1200K. Redox characteristics of Cu-ferrites were studied using the thermal gravimetric analysis technique. Also, structure change of Cu-ferrite during thermal reduction was investigated using the high temperature controlled XRD. In results, oxygen release of Cu-ferrite during the thermal reduction was initiated at oxygen site combined with Cu. Consequently, oxygen release amount of Cu-ferrite was increased with increase of Cu molar ratio of Cu-ferrite. It was found that thermal reduction of Cu-ferrite was begun at $875^\circ{C}$. It was confirmed that structure of Cu-ferrite was changed to metal and cation excess metal oxide during the thermal reduction step.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.389-397
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• 1996

Gatric mucosa is exposed to toxic, reactive oxygen species generated within the lumen. Nitric oxide protected acetaminophen-induced hepatotoxicity by maintaining glutathione homeostasis. The present study examined the role of nitric oxide in mediating hydrogen peroxide - induced damage to gastric cells. Hydrogen peroxide was generated by glucose oxidase acting on ${\beta}-D-glucose$. L-arginine, $N^G-nitro-L-arginine$ methyl ester, or $N^G-nitro-L-arginine$ were treated to the cells with glucose/glucose oxidase. Lipid peroxidation and nitrite release and cellular content of glutathione were determined. As a result, dose - dependent increase in lipid peroxide production as well as dose - dependent decrease in nitrite release and cellular glutathione content were observed in glucose/glucose oxidase - treated cells. Pretreatment of L-arginine, a substrate for nitric oxide synthase, prevented the increase of lipid peroxide production and the reduction of nitrite release as well as glutathione content. Inhibitors of nitric oxide synthase such as $N^G-nitro-L-arginine$ methyl ester and $N^G-nitro-L-arginine$ did not protect hydrogen peroxide - induced cell damage. In conclusion, nitric oxide protects gestric cells from hydrogen peroxide possibly by inhibiting lipid peroxidation and by preserving cellular glutathione stores.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.5
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• pp.416-423
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• 2009

High-temperature steam electrolysis (HTSE) using solid oxide cell is a challenging method for highly efficient large-scale hydrogen production as a reversible process of solid oxide fuel cell (SOFC). The overall efficiency of the HTSE hydrogen and synthesis gas production system was analyzed thermo-electrochemically. A thermo-electrochemical model for the hydrogen and synthesis gas production system with solid oxide electrolysis cell (SOEC) and very high temperature gas-cooled reactor (VHTR) was established. Sensitivity analyses with regard to the system were performed to investigate the quantitative effects of key parameters on the overall efficiency of the production system. The overall efficiency with SOEC and VHTR was expected to reach a maximum of 58% for the hydrogen production system and to 62% for synthesis gas production system by improving electrical efficiency, steam utilization rate, waste heat recovery rate, electrolysis efficiency, and thermal efficiency. Therefore, overall efficiency of the synthesis production system has higher efficiency than that of the hydrogen production system.