Showa Denko Research Articles

Surfactin as an ingredient in cosmetic industry: Benefits and trends.

Surfactin is a natural surfactant almost exclusively produced by Bacillus species with excellent physical-chemical, and biological properties. Among innovative applications, surfactin has been recently used as an ingredient in formulations. The antibacterial and anti-acne activities, as well as the anti-wrinkle, moisturizing, and cleansing features, are some of the reasons this lipopeptide is used in cosmetics. Considering the importance of biosurfactants in the world economy and sustainability, their potential properties for cosmetic and dermatological products, and the importance of patents for technological advancement in a circular bioeconomy system, the present study aims to review all patents involving surfactin as an ingredient in cosmetic formulas. This review was conducted through Espacenet, wherein patents containing the terms "cosmetic" and "surfactin" in their titles, abstracts, or claims were examined. Those patents that detailed a specific surfactin dosage within their formulations were selected for analysis. All patents, irrespective of their publication date, from October 1989 to December 2022, were considered. Additionally, a comprehensive search was performed in the MEDLINE and EMBASE databases, spanning from their inception until the year 2023. This complementary search aimed to enrich the understanding derived from patents, with a specific emphasis on surfactin, encompassing its associated advantages, efficacy, mechanisms of action on the skin, as well as aspects related to sustainability and its merits in cosmetic formulations. From the 105 patents analysed, 75% belong to Japan (54), China (14), and Korea (9). Most of them were submitted by Asian companies such as Showa Denko (15), Kaneka (11) and Kao Corporation (5). The formulations described are mainly emulsions, skincare, cleansing, and haircare, and the surfactin dose does not exceed 5%. Surfactin appears in different types of formulas worldwide and has a high tendency to be used. Surfactin and other biosurfactants are a promising alternative to chemical ingredients in cosmetic formulations, guaranteeing skin health benefits and minimizing the impact on the environment.

Asian Paints licenses VAM technology from Showa Denko

Asian Paints licenses VAM technology from Showa Denko

Showa Denko to license vinyl acetate monomer technology to Asian Paints, India

Showa Denko to license vinyl acetate monomer technology to Asian Paints, India

Global carbon nanotubes market report to 2030 - featuring Arkema, Carbon Solutions, Showa Denko and Unidym among others

Global carbon nanotubes market report to 2030 - featuring Arkema, Carbon Solutions, Showa Denko and Unidym among others

(Digital Presentation) Effect of Iron Doping on Oxygen Reduction Activity of Zirconium Oxides Containing Carbon and Nitrogen Using Pyrazine Carboxylic Acid As Platinum Alternative Cathodes for PEFC

The use of carbon-supported platinum catalysts as cathode of present polymer electrolyte fuel cells (PEFCs) have some problems such as high cost and low amount of resources of platinum. Therefore, we have attempted to develop substitute of platinum based on group 4 transition metal oxides. We found that stable oxygen vacancies on the surface and lattice distortion by doping foreign elements of these metal oxides could act as active sites of oxygen reduction reaction (ORR) [1]. However, although zirconium oxides show some ORR activity, the onset potential of the ORR still remains low. Then, we focused on the improvement of the ORR activity by an addition of iron ions to zirconium oxides according to the research of P. Madkikar et. al. [2]. In this study, we used pyrazine carboxylic acid as ligand of metal ions to prepare zirconium-iron complexes including carbon and nitrogen as precursors. The precursors were heat-treated under low oxygen pressure to obtain the iron-added zirconium oxide-based catalysts, which are designated as ZrOx-Fe. We investigated the correlation between the ORR activity and physical characteristics such as crystalline phase.ZrOx-Fe catalysts were synthesized according to the previous patent [3]. We prepared zirconium complexes solutions by mixing zirconium butoxide and acetic acid in acetylacetone as a solvent. On the other hand, we also prepared iron complexes solutions by mixing iron acetic acid and pyrazine carboxylic acid in mixed solvents of water, ethanol and acetic acid. The amount of the iron addition was changed in atomic ratios of 0, 0.004, 0.01, 0.1, and 0.2 against Zr atoms. The iron atomic ratio of 0.004 was selected according to P. Madkikar’s results, because Fe atomic ratio of 0.0036 caused the highest ORR activity in the report [2]. After mixing of two solutions, the solutions were stirring several days, and the precursors were obtained by evaporation and vacuum drying. These precursors were heat-treated under argon including 2 % hydrogen and 0.05 % oxygen for low oxygen pressure oxidation, and finally ZrOx-Fe catalysts were obtained. To investigate the effect of Fe addition to zirconium oxides, we also synthesized iron-based catalyst without Zr in the same way. Electrochemical measurements were conducted in the solution of 0.5 M H2SO4 at 30 oC. In this study, we used the ORR onset potential as the parameter of the ORR activity, which was defined as the potential when the ORR current (i ORR) was 0.01 ampere per a mass of the whole catalysts.Among the ZrOx-Fe catalysts prepared in this study, ZrOx-Fe with the Fe atomic ratio of 0.1 showed the highest E ORR, which was designated as ZrOx-Fe(0.1). Therefore, we compared with ZrOx and FeOx prepared by the same way as well as conventional catalysts. Fig. 1 shows the ORR polarization curves of the ZrOx, ZrOx / CNT [1], ZrOx-Fe / KB [2], FeOx and ZrOx-Fe(0.1) catalysts. As shown in Fig.1, the ZrOx-Fe(0.1) catalyst had highest ORR onset potential among these catalysts. Comparing with ZrOx, FeOx and ZrOx-Fe(0.1), the Fe addition into zirconium oxide was essential to increase the ORR onset potential. In addition, the onset potential of the ZrOx-Fe(0.1) was higher than that of the ZrOx-Fe / KB [2] and our previous ZrOx / CNT [1]. The onset potential of the ZrOx-Fe(0.1) was exceeded 0.9 V that we have never been able to reach with zirconium oxides. Therefore, the addition of iron to zirconium oxides improved drastically the quality of the active sites of the ORR.Next, we examined crystalline phase of all ZrOx-Fe catalysts with XRD. All ZrOx-Fe catalysts were consisted of ZrO2 monoclinic or tetragonal phase. We calculated monoclinic rate in each catalyst using the equation in the literature [4]. The change of atomic ratio of Fe caused the different monoclinic rate. A positive correlation between the ORR onset potentials and the monoclinic rates of the ZrOx-Fe was obtained. Thus, the ORR onset potential increased with increasing the monoclinic rate in the catalysts, suggesting that the monoclinic phase formed the active sites of the ORR.AcknowledgementThe authors thank the financial support of the New Energy and Industrial Technology Development Organization (NEDO), JSPS grants-in-aid for scientific research, and ENEOS Tonen General Sekiyu Research / Development Encouragement & Scholarship Foundation.References(1) A. Ishihara et. al., Int. J. Hydro. Energy, 45, 5438 (2019).(2) P. Madkikar et. al., J. Electrochem. Soc., 166, F3032 (2019).(3) Showa Denko Corp., R. Monden et. al., Oxygen reduction catalysts, the methods of these, and polymer electrolyte fuel cells, JP 2013-240785, 2013-12-05.(4) H. Toraya et. al., J. Am. Ceram. Soc., 67, C119 (1984). Figure 1

Photocatalytic Properties of TiO2 Electrodes on Stainless Steel Substrate Using Optimized TiO2 Pastes for Screen Printing

Solar cells and panels are one of the applications by converting solar energy into electrical energy. However, there exist environmental impacts such as deforestation, microclimate change, soil quality deterioration and migration of wildlife animals when a large amount of land areas are used for solar power plants. One of the solutions to those issues is to build floating solar panels in dams and lakes. We still need to apply large water areas, i.e., oceanic areas for those floating solar cells. Our research group has been studying floating solar cells that are compatible and have the potential to be used in marine environments. This solar cell is made of titanium dioxide photoanode and copper oxides photocathode with seawater electrolyte. Titanium dioxide (TiO2) has been studied for its photocatalytic properties. In this study, the photocatalytic properties of screen printed TiO2 electrodes on stainless steel substrate prepared from different pastes of TiO2 were examined and analysed.Type 329J4L stainless steel with duplex phase structure (ferritic + austenitic) was used as a substrate for TiO2 electrode. At first, the surface of the substrate was polished by sandpaper of 60 grade to form a grid pattern on it. The substrate was then cleaned by acetone in ultrasonic cleaner for 10 minutes and rinsed with distilled water. After that, the substrate was treated with passivation treatment. In this treatment, the substrate was placed in 10 % nitric acid (HNO3) solution at 60 ºC for 30 minutes and then rinsed with distilled water. After passivation treatment, the substrate was printed with TiO2 paste and heat treated at 150 ºC for 60 minutes to form the first layer of TiO2 film on the substrate. The second layer of TiO2 film was formed by screen printing of TiO2 paste followed by heat treatment at 550 ºC for 30 minutes. Finally, the electrode was solder welded and coated with epoxy resin to get ready for the measurement. Different TiO2 pastes were prepared and used for printing on the substrate. The first one was using the purchased TiO2 paste (SP-100 Showa Denko, Japan). The other ones were prepared from TiO2 powder (Sigma-Aldrich). Those pastes were prepared using the certain ratios of TiO2 powder, nitric acid, acetic acid, tritonX-100, and polyethylene glycol.The potential and polarization measurement of the electrodes were carried out in artificial seawater. The irradiation measurement was conducted using a xenon lamp (150 W) with a calibrated wavelength range of 250 nm to 800 nm and output irradiation intensity of 10.5 mW/cm2. Saturated calomel electrode (SCE) was used as a reference electrode and the potentio-galvanostat (SDPS-511U, Japan) was used as the measuring device. Figure 1 shows the potential values over a 2 -hour irradiation testing of two TiO2 electrodes prepared from two different pastes. The optimized TiO2 paste showed higher photopotential performance over time than the merchandized one. The surface and microstructures of the electrodes before and after the measurement were examined by Scanning Electron Microscope (SEM) and the pastes were investigated by Thermogravimetry Differential Thermal Analysis (TG-DTA) and X-ray powder diffraction (XRD). The results are planned to be presented in the upcoming ECS conference meeting. Figure 1

Showa Denko, SK mull US chip chemicals

Showa Denko, SK mull US chip chemicals

Showa Denko and SK mull US semiconductor material plant

Showa Denko and SK mull US semiconductor material plant

Development of Ag/CNT Films As Electrical Connectors Using a Cyanide-Free Electroplating Bath

Ag films as an electrical contact material have been applied to electrical devices because of the best electrical conductivity and is relatively low cost compared to that of Au. However, Ag is easily sulfurized in the air. In addition, Ag connectors with extremely soft are easy to wear. These are responsible for the increasing in resistance between electrical connectors. To overcome these issues, Ag/graphite1 with wear resistant property and Ag/CNTs2,3 with excellent mechanical strength have been studied. In the later composite, CNTs function as electrical pass even in the degradation derived from sulfidation and friction. This is the motivation of the development of Ag composite as a connector. The Ag/CNT composites have been prepared by using toxic cyanide electroplating baths4-6 which suppress dendrite growth of Ag by stable complex with cyanide ions. We focused on the iodide aqueous solutions instead of toxic cyanide electroplating baths for realizing eco-friendly approach. In the present study, the pH effect in iodide aqueous solutions on current efficiency of Ag electroplating was investigated. Then, we tried to produce Ag/CNT composite with high electrical contact properties and remarkable wear resistance. The pH in iodide-electroplating solutions was adjusted using H2SO4 or KOH. CNTs (VGCF, SHOWA DENKO K.K.) were used without further purification, and then the CNTs were dispersed into the iodide-electroplating solutions. Co-electrodeposition of Ag/CNT was performed under galvanostatic conditions using a pure Ag plate as the anode and a pure Cu plate as the cathode at temperature of 298 K. The concentration of I3 − causing poor current efficiency during the electroplating was determined by iodometric titration of I2 (I3 − ⇄ I− + I2) using Na2S2O3-dissolved aqueous solution (I2 + 2S2O3 2− → S4O6 2− + 2I−).7 Under the condition of low pH at atmosphere, I− is generally oxidized to I2, and then the I2 reacts with I− to form I3 − (I2 + I− ⇄ I3 −). Considering the equilibrium potentials of Ag+/Ag = +0.799 V vs. SHE and I3 −/I− = +0.536 V vs. SHE, the reduction of Ag+ (Ag electrodeposition) proceeds preferentially. However, at the presence of [Ag m I n ] m − n complex ions with a relatively high stability constant, the equilibrium potential of Ag+/Ag shifts to negative and thereby consumes electrons (currents) by the reduction of I3 − during the electroplating. Therefore, the I3 − formation should be suppressed. In the solution adjusted to pH=1, the I3 − concentration was suddenly increased, whereas in the solution of pH=12, the concentration was maintained below detection limit even after 30 days (Fig. 1a). The current efficiency was significantly improved, and 100% efficiency was achieved only when adjusting to pH=12. In the composite electroplating-film prepared using the solution (pH=12), we can clearly observe that CNTs are uniformly immobilized by Ag film and incorporated inside the film (Fig. 1b). The structure with large amount of CNTs should offer not only the high electrical contact property but also the improved wear resistance.References) 1. W. Lv, T. S. Chen, K. Q. Zheng, Z. G. Zhang, Werkst. Korros., 69, 933 (2018). 2. Y. Litovka, I. Dyakov, R. Stolyarov, V. Kulakov, A. Zhigachev, V, Korenkov, Mater. Sci. Eng., 693, 012005 (2019). 3. M. Fujishige, M. Sekino, K. Fujisawa, S. Morimoto, K. Takeuchi, S. Arai, A. Kawai, Appl. Phys. Express, 3, 065801 (2010). 4. V. I. Rigou, G. Marginean, D. Frunzăverde, C. V. Câmpian, Wear, 290, 61 (2012). 5. I. Krastev, T. Valkova, A. Zielonka, J. Appl. Electrochem., 34, 79 (2004). 6. Y. Zhou, Y. Huo, J. Mater. Sci. Mater. Electron., 27, 931 (2016). 7. W. Gottardi, J. Pfleiderer, Anal. Bioanal. Chem., 382, 1328 (2005). Figure 1

Business Roundup

BUSINESS Business Roundup ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2020, 98 (2), p 13January 13, 2020Cite this:C&EN 98, 2, 13AbstractFormosa Petrochemical has received air permits from Louisiana’s Department of Environmental Quality for a $9 billion project it is considering building in Saint James Parish. The project still requires a final go-ahead from Formosa. Showa Denko will build a $28 million facility in Shanghai to make high-purity gases for the electronics industry. Output will include nitrous oxide, used to form oxidized films, and octafluorocyclobutane, used to etch the films. Livent has lowered its earnings forecast for the fourth quarter and full-year 2019. The company, a spin-off from FMC, attributes the revision to lower-than-expected prices for lithium chemicals. Ionomr Innovations, based in Vancouver, British Columbia, has raised $3 million in a seed round of funding to develop ion-exchange membranes and related polymer products. The start-up makes materials for fuel cells, hydrogen production, and batteries. Boragen, one of C&EN’s 10 Start-Ups to Watch in 2017, has raised $2 million from existing investorsView: PDF | Full Text HTML

Showa Denko to acquire Hitachi Chemical

In a large merger of two Japanese chemical makers with electronic material businesses, Showa Denko is buying Hitachi Chemical for about $8.9 billion. Hitachi had operating income of about $440 million on sales of $6.3 billion in its most recent fiscal year. About 40% of its sales come from materials, including chemical mechanical planarization slurries, epoxy compounds, and anode materials for lithium-ion batteries. The company also makes auto components, batteries, and printed circuit boards. Showa Denko had operating income of $1.7 billion on sales of $9.1 billion in 2018. The company makes petrochemicals and industrial gases in addition to electronic materials. It also has nonchemical businesses, including aluminum and building materials. Showa Denko says it wants to grow its high-tech businesses as a response to stiffening competition from China. Jefferies stock analyst Yoshihiro Azuma is negative on the deal. He is particularly worried about the amount of debt Showa Denko

Mergers reach Japan

With two midsize Japanese chemical makers merging and rumors floating that two other firms may combine, experts say consolidation may be coming to the fragmented Japanese chemical industry. After the announcement of merger discussions in May, Nippon Shokubai and Sanyo Chemical say they have agreed to combine into a new company, to be called Synfomix. And reports came out of Japan last month that Showa Denko was considering the acquisition of Hitachi Chemical, among other possible targets. The combination of Shokubai and Sanyo will create a firm with annual sales of roughly $4.7 billion. Shokubai is the larger, with 2018 sales of $3.2 billion. Both players focus on specialties, particularly materials used in health and personal care. Notably, both produce superabsorbent polymers (SAPs), the key material in diapers. Vertically integrated, Shokubai is the world’s largest producer of SAPs. Sanyo is less focused on SAPs and offers 3,000 materials used in

Anode material firm raises $18 million

Washington State–based Group14 Technologies has raised $18 million from investors to scale up output of its silicon-based anode material, which it says could significantly enhance the performance of lithium-ion batteries. The investors are the industrial companies Amperex Technologies, BASF, Cabot, and Showa Denko, as well as the venture capital firm OVP Venture Partners. Group14 says its anode material, composed of nanostructured porous carbon and silicon, is a drop-in replacement for graphite.

Showa Denko sticks with nonstick coatings

Japan’s Showa Denko has signed a deal to buy Industrielack AG, a Swiss maker of nonstick coatings, from the private equity firm Helvetica Capital. ILAG employs 120 people and makes fluorochemical-, silicone polyester-, and ceramic-based coatings for cookware and industrial products at plants in Switzerland and China. The newly acquired business complements GMM Nonstick Coatings, a US-based firm that Showa Denko bought in 2017. After the ILAG acquisition, Showa Denko says, it will have $60 million in annual nonstick coating sales out of a global market worth $1.2 billion.

The role of cross-species microphysiological systems in understanding target organ toxicity in Oncology drug projects

The eosinophilia-myalgia syndrome (EMS) outbreak that occurred in the USA and elsewhere in 1989 was caused by the ingestion of Showa Denko K.K. (SD) L-tryptophan (L-Trp). “Six compounds” detected in the L-Trp were reported as case-associated contaminants. Recently the final and most statistically significant contaminant, “Peak AAA” was structurally characterized. The “compound” was actually shown to be two structural isomers resulting from condensation reactions of L-Trp with fatty acids derived from the bacterial cell membrane. They were identified as the indole C-2 anteiso (AAA1-343) and linear (AAA2-343) aliphatic chain isomers. Based on those findings, we utilized a combination of on-line HPLC-electrospray ionization mass spectrometry (LC–MS), as well as both precursor and product ion tandem mass spectrometry (MS/MS) to facilitate identification of a homologous family of condensation products related to AAA1-343 and AAA2-343. We structurally characterized eight new AAA1-XXX/AAA2-XXX contaminants, where XXX represents the integer molecular ions of all the related homologs, differing by aliphatic chain length and isomer configuration. The contaminants were derived from the following fatty acids of the bacterial cell membrane, 5-methylheptanoic acid (anteiso-C8:0) for AAA1-315; n-octanoic acid (n-C8:0) for AAA2-315; 6-methyloctanoic acid (anteiso-C9:0) for AAA1-329; n-nonanoic acid (n-C9:0) for AAA2-329; 10-methyldodecanoic acid (anteiso-C13:0) for AAA1-385; n-tridecanoic acid (n-C13:0) for AAA2-385; 11-methyltridecanoic acid (anteiso-C14:0) for AAA1-399; and n-tetradecanoic acid (n-C14:0) for AAA2-399. The concentration levels for these contaminants were estimated to be 0.1–7.9 μg / 500 mg of an individual SD L-Trp tablet or capsule The structural similarity of these homologs to case-related contaminants of Spanish Toxic Oil Syndrome (TOS) is discussed.

Status and Trends in Epitaxy and Defects

SiC-powered devices which reduce the power loss, size, and weight of power converters are gradually appearing in the power electronics market. From now on, cost reduction and quality improvement of SiC epitaxial wafers is required to further increase their popularity. This paper describes the state of development of mass production of the epi-wafer at Showa Denko K. K.

Toshiba pure hydrogen fuel cell in operation at new hotel in Kawasaki

In Japan, Toshiba Energy Systems & Solutions Corporation (Toshiba ESS) has delivered a pure hydrogen fuel cell system for Showa Denko KK (SDK), which has been installed in the new Kawasaki King Skyfront Tokyu REI hotel in Kawasaki City, Kanagawa Prefecture.

Peak AAA fatty acid homolog contaminants present in the dietary supplement l-Tryptophan associated with the onset of eosinophilia-myalgia syndrome

The eosinophilia-myalgia syndrome (EMS) outbreak that occurred in the USA and elsewhere in 1989 was caused by the ingestion of Showa Denko K.K. (SD) L-tryptophan (L-Trp). “Six compounds” detected in the L-Trp were reported as case-associated contaminants. Recently the final and most statistically significant contaminant, “Peak AAA” was structurally characterized. The “compound” was actually shown to be two structural isomers resulting from condensation reactions of L-Trp with fatty acids derived from the bacterial cell membrane. They were identified as the indole C-2 anteiso (AAA1-343) and linear (AAA2-343) aliphatic chain isomers. Based on those findings, we utilized a combination of on-line HPLC-electrospray ionization mass spectrometry (LC–MS), as well as both precursor and product ion tandem mass spectrometry (MS/MS) to facilitate identification of a homologous family of condensation products related to AAA1-343 and AAA2-343. We structurally characterized eight new AAA1-XXX/AAA2-XXX contaminants, where XXX represents the integer molecular ions of all the related homologs, differing by aliphatic chain length and isomer configuration. The contaminants were derived from the following fatty acids of the bacterial cell membrane, 5-methylheptanoic acid (anteiso-C8:0) for AAA1-315; n-octanoic acid (n-C8:0) for AAA2-315; 6-methyloctanoic acid (anteiso-C9:0) for AAA1-329; n-nonanoic acid (n-C9:0) for AAA2-329; 10-methyldodecanoic acid (anteiso-C13:0) for AAA1-385; n-tridecanoic acid (n-C13:0) for AAA2-385; 11-methyltridecanoic acid (anteiso-C14:0) for AAA1-399; and n-tetradecanoic acid (n-C14:0) for AAA2-399. The concentration levels for these contaminants were estimated to be 0.1–7.9 μg / 500 mg of an individual SD L-Trp tablet or capsule The structural similarity of these homologs to case-related contaminants of Spanish Toxic Oil Syndrome (TOS) is discussed.

Structure determination of disease associated peak AAA from l-Tryptophan implicated in the eosinophilia-myalgia syndrome

The eosinophilia-myalgia syndrome (EMS) outbreak of 1989 that occurred in the USA and elsewhere was caused by the ingestion of l-Tryptophan (L-Trp) solely manufactured by the Japanese company Showa Denko K.K. (SD). Six compounds present in the SD L-Trp were reported to be case-associated contaminants. However, “one” of these compounds, Peak AAA has remained structurally uncharacterized, despite the fact that it was described as “the only statistically significant (p=0.0014) contaminant”. Here, we employ on-line microcapillary-high performance liquid chromatography-electrospray ionization mass spectrometry (LC–MS), and tandem mass spectrometry (MS/MS) to determine that Peak AAA is in fact two structurally related isomers. Peak AAA1 and Peak AAA2 differed in LC retention times, and were determined by accurate mass-LC–MS to both have a protonated molecular ion (MH+) of mass 343.239Da (Da), corresponding to a molecular formula of C21H30N2O2, and possessing eight degrees of unsaturation (DoU) for the non-protonated molecule. By comparing the LC–MS and LC–MS-MS retention times and spectra with authentic synthetic standards, Peak AAA1 was identified as the intermolecular condensation product of L-Trp with anteiso 7-methylnonanoic acid, to afford (S)-2-amino-3-(2-((S,E)-7-methylnon-1-en-1-yl)-1H-indol-3-yl)propanoic acid. Peak AAA2 was determined to be a condensation product of L-Trp with decanoic acid, which produced (S)-2-amino-3-(2-((E)-dec-1-en-1-yl)-1H-indol-3-yl)propanoic acid.

Exploring Active Sites in Nitrogen Doped Carbon Nanotube Based Electrocatalyst

Carbon nanotube based electrocatalysts have been expected to be the alternative catalysts for the Oxygen Reduction Reaction (ORR) due to their competitively high activity and low cost compared with the conventional Pt/C catalysts. Although pristine carbon nanotubes are known to exhibit poor ORR activity, doping heteroatoms, introducing transition metals and controlling carbon structure can be applied to enhance their ORR activity extensively.[1-4] Nevertheless, the origin of the ORR activity is still not well understood. The Metal-Nitrogen-Carbon complex (MNC) and Nitrogen containing carbon (CNx) related sites have been proposed to be the possible active sites in nitrogen doped carbon materials. In both MNC and CNx structures, it is widely accepted that pyridinic nitrogen plays an important role in the ORR. To further verify the ORR mechanism, in this study, we conduct durability tests to study the relationship between ORR activity and nitrogen structures. The LSV of HA-N900, HA-N900 after durability test (Dur-HA-N900) and re-nitrogen doping of Dur-HA-N900 (Re-N900) in 0.1M HClO4 were shown in Figure 1. As pyridinic nitrogen is always related to the high ORR activity, it is reasonable that along with the ORR activity decreases after the durability test, the pyridinc nitrogen concentration also decreases. Indeed, this phenomenon was confirmed by conducting XPS measurements for the samples. On the other hand, interestingly, we found that even though by introducing pyridinc nitrogen to the same level as that before the durability test through re-nitrogen doping, the ORR activity could not return to the initial state. The ORR activity, along with the role of different kind of nitrogen composition and the metal impurities’ effect will be discussed further on the conference through detailed characterizations with X-ray Photoelectron Spectroscopy (XPS), Temperature Programed Desorption (TPD) and Raman Spectroscopy. The MWCNTs used were provided by Showa Denko KK Japan (VGCF-X, diameter: 15nm, approximate length: 3μm; containing Fe impurities <1 wt%). As a precursor, functionalized and purified MWCNT was obtained by heat and acid treatment in the mixture of H2SO4/HNO3 (HA). [5] Then HAMWCNTs were nitrogen doped in 10% NH3/ Argon gas at 900℃(HA-N900). The durability test was conducted by cycling the catalysts under Ar gas bubbling in 0.1M HClO4 with a scan rate of 500mV/s, voltage window [1.0-1.5] V vs. RHE for 1600 cycles. Acknowledgements This work partially was supported by the Center for Low Carbon Society Strategy (LCS) and Shin-Etsu Chemical Co. Ltd. , Japan. Their contribution is greatly appreciated. Reference [1] Waki, Keiko. "Nitrogen Doped Defective Carbon Nanotube Electrocatalyst for Oxygen Reduction Reaction." PRiME 2016/230th ECS Meeting (October 2-7, 2016). Ecs, 2016. [2] Waki, Keiko, et al. "Non-nitrogen doped and non-metal oxygen reduction electrocatalysts based on carbon nanotubes: mechanism and origin of ORR activity." Energy & Environmental Science 7.6 (2014): 1950-1958. [3] Li, Yanguang, et al. "An oxygen reduction electrocatalyst based on carbon nanotube-graphene complexes." Nature nanotechnology 7.6 (2012): 394-400. [4]Tao, Li, et al. "Edge-rich and dopant-free graphene as a highly efficient metal-free electrocatalyst for the oxygen reduction reaction." Chemical Communications 52.13 (2016): 2764-2767. [5] Oktaviano, Haryo S, et al. "Nano-drilled multiwalled carbon nanotubes: characterizations and application for LIB anode materials." Journal of Materials Chemistry 22.48 (2012): 25167-25173. Figure 1