• Journal of the Korean institute of surface engineering
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• v.51 no.5
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• pp.332-336
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• 2018

Alkaline oxygen electrocatalysis, targeting anion exchange membrane alkaline-based metal-air batteries has become a subject of intensive investigation because of its advantages compared to its acidic counterparts in reaction kinetics and materials stability. However, significant breakthroughs in the design and synthesis of efficient oxygen reduction catalysts from earth-abundant elements instead of precious metals in alkaline media still remain in high demand. One of the most inexpensive alternatives is carbonaceous materials, which have attracted extensive attention either as catalyst supports or as metal-free cathode catalysts for oxygen reduction. Also, carbon composite materials have been recognized as the most promising because of their reasonable balance between catalytic activity, durability, and cost. In particular, heteroatom (e.g., N, B, S or P) doping on carbon materials can tune the electronic and geometric properties of carbon, providing more active sites and enhancing the interaction between carbon structure and active sites. Here, we focused on boron and nitrogen doped nanocarbon composit (BNC nanocarbon) catalysts synthesized by a solution plasma process using the simple precursor of pyridine and boric acid without further annealing process. Additionally, guidance for rational design and synthesis of alkaline ORR catalysts with improved activity is also presented.

• Textile Coloration and Finishing
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• v.31 no.1
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• pp.33-41
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• 2019

In this report, nano-sized catalysts were introduced onto fabric surface to eliminate toxic chemicals assisted by physical adsorption. For chemical removal of toxic compounds, a series of zirconium-containing catalysts were synthesized and treated on fabric to catalyze the hydrolysis and oxidation of target molecules. Antimicrobial was also introduced for the research purpose to prove the compatibility of as-synthesized catalysts with other solutions. Zirconium ligated with hydroxyl group and MOF(Metal-Organic Frameworks) were exploited as catalyst for removal of toxic compounds, while zinc complex was used for an antimicrobial to culminate in a chemical shield. Once fabrics were functionalized, fabrics were washed 2 or 5 times for a washing durability test. The amount of catalyst in textile were measured by ICP-MS and weight increasing ratio of fabrics.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.387-391
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• 2019

A highly porous Ni@MIL-101catalyst for urea oxidation was synthesized by anchoring Ni into a Cr-based metal-organic framework, MIL-101, particles. The morphology, structure, and composition of as synthesized Ni@MIL-101 catalysts were characterized by X-Ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electro-catalytic activity of the Ni@MIL-101catalysts towards urea oxidation was investigated using cyclic voltammetry. It was found that the structure of Ni@MIL-101 retained that of the parent MIL-101, featuring a high BET surface area of $916m^2g^{-1}$, and thus excellent electro-catalytic activity for urea oxidation. A $urea/H_2O_2$ fuel cell with Ni@MIL-101 as anode material exhibited an excellent performance with maximum power density of $8.7mWcm^{-2}$ with an open circuit voltage of 0.7 V. Thus, this work shows that the highly porous three-dimensional Ni@MIL-101 catalysts can be used for urea oxidation and as an efficient anode material for urea fuel cells.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.61-66
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• 2022

This study is to increase the surface area and maximize the effect of the catalyst by coating a nanometersized metal catalyst material on the anode layer using atomic layer deposition (ALD) technology. ALD process is known to produce uniform films with well-controlled thickness at the atomic level on substrates. We measured the performance by coating metals (Ni) on Ni/YSZ, which is the most widely known anode material for solid oxide fuel cells. ALD coatings began to show a decrease in cell performance over 3 nm coatings.

• Journal of Electrochemical Science and Technology
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• v.13 no.4
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• pp.417-423
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• 2022

With the emerging importance of catalysts for water electrolysis, developing efficient and inexpensive electrocatalysts for water electrolysis plays a vital role in renewable hydrogen energy technology. In this study, a 1nm thickness of TiC-supported Ru catalyst for hydrogen evolution reaction (HER) has been successfully fabricated using an electron (E)-beam evaporator and thermal decomposition of gaseous CH₄ in a furnace. The prepared Ru/TiC catalyst exhibited an outstanding performance for alkaline hydrogen evolution reaction with an overpotential of 55 mV at 10 mA cm^-2. Furthermore, we demonstrated that the outstanding HER performance of Ru/TiC was attributed to the high surface area of the support and the metal-support interaction.

• Clean Technology
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• v.20 no.2
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• pp.189-201
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• 2014

Partial oxidation, $CO_2$ reforming and the oxidative $CO_2$ reforming of $CH_4$ to produce synthesis gas over supported Ni hydrotalcite-type ($Ni_{0.5}Ca_{2.5}Al$ catalyst) catalysts were carried out and the effects of metal supports (i.e.; Mg and Ca) on the formation of a stable double-layer structure on the catalysts were evaluated. The $CH_4$ reforming stability was determined to be affected by the differences in the interaction strength between the active Ni ions and support metal ions. Only a Ni-Mg-Al composition produced a highly stable hydrotalcite-type double-layered structure; while the Ni-Ca-Al-type composition did not. Such structure provides excellent stability for the catalyst (-80% efficiency) as confirmed by the long-term $CO_2$ reforming test (-100 h), while the Ni-Ca-Al catalyst exhibited deactivation phases starting at the beginning of the reaction. The interaction strength between the active metal (Ni) and the supporting components (Mg and Al) was determined by temperature-programed reduction (TPR) analyses. The affinity was also confirmed by the TPR temperature because the Ni-Mg-Al catalyst required a higher temperature to reduce the Ni relative to the Ni-Ca-Al catalyst. The highest initial activity for synthesis gas production was observed for the $Ni_{0.5}Ca_{2.5}Al$ catalyst; however, this activity decreased quickly due to coke formation. The $Ni_{0.5}Ca_{2.5}Al$ catalyst exhibited a high reactivity and was more stable than the other catalysts because it had a higher resistance to coke formation.

• Journal of the Korean Electrochemical Society
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• v.4 no.4
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• pp.172-175
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• 2001

Nanophase catalyst layer for direct methanol fuel cell has been fabricated by magnetron sputtering method. Catalyst metal targets and carbon were sputtered simultaneously on the Nafion membrane surface at abnormally higher gas (Ar/He mixture) pressure than that of normal thin film processing. They could be coated as a novel structure of catalyst layer containing porous PtRu or Pt and carbon particles both in nanometer range. Membrane electrode assembly made with this layer led to a reduction of the catalyst loading. At the catalyst loading of 1.5mg $PtRu/cm^2$ for anode and 1mg $Pt/cm^2$ for cathode, it could provide $45 mW/cm^2$ in the operation at 2 M methanol, 1 Bar Air at 80"C. It is more than $30\%$ increase of the power density performance at the same level of catalyst loading by conventional method. This was realized due to the ultra fine particle sizes and a large fraction of the atoms lie on the grain boundaries of nanophase catalyst layer and they played an important role of fast catalyst reaction kinetics and more efficient fuel path. Commercialization of direct methanol fuel cell for portable electronic devices is anticipated by the further development of such design.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.92-97
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• 2008

Selective catalytic reduction (SCR) of NO with ammonia was carried out over the physical mixture of $MnO_2$ and K or Cu-loaded activated carbons (AC) at low temperature. Introduction of oxygen affected positively the reduction of NO. Metal-impregnated AC showed significantly enhanced catalytic activity. Without water, the mixed catalyst of $MnO_2$ and K-loaded AC exhibited the best activity in the reduction of NO at $120^{\circ}C$. On the contrary, the activities of all the catalysts were significantly diminished in the presence of water. The mixed catalyst of $MnO_2$ and Cu-loaded AC treated with nitric acid and heat (1 : 1, w/w) exhibited the better activity for the reduction of NO than each single catalyst in presence of water.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.537-544
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• 2011

This work was conducted to investigate the oxidation characteristics of methane having the highest ignition temperature among the other hydrocarbon gases using transition metal catalysts. The catalyst used for methane oxidation was manganese oxide having a various oxidation number, such as MnO, $MnO_2$, $Mn_2O_3$, $Mn_3O_4$, $Mn_4O_5$. The manganese oxide(MnxOy) catalyst is impregnated on $TiO_2$, $Al_2O_3$ for methane oxidation. To enhanced both of activity and life time of catalysts, Ni and Co was used as a promoter. In this study, various co-catalysts were synthesized by using excess wet impregnation method. The effect of reaction temperature and space velocity was measured to calculate the activity of catalysts such as, activation energy of $T_{50}$, and $T_{90}$. The life time of bi-metallic manganese mixture, such as Mn-Co and Mn-Ni catalysts, were increased more 10 % than manganese oxide catalyst, but activity of those was decreased slightly.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.1
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• pp.8-14
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• 2015

In this study, the model biomass was used for hydrogen production by supercritical water gasification (SCWG). Model biomasses were glycerol, glycine, lignin and cellulose. The feed concentration was set to 1 wt%. Experiments were conducted in a reactor at $440^{\circ}C$ and above 26.3 MPa for 30 min. The effects of catalysts such as alkali metal salt ($K_2CO_3$ and $Na_2CO_3$) and transition metal salts ($Ni(NO_3)_2$, $Fe(NO_3)_3$ and $Mn(NO_3)_2$) on the gasification were systematically investigated. No tar or coke was observed in all experiments. The results showed that the gasification efficiency increased with various catalysts. For the cellulose and glycerol, all catalysts were effective for the promoted $H_2$ production compared with no catalyst. The significant decrease of $H_2$ production compared with no catalyst was observed with $Na_2CO_3$ and $Fe(NO_3)_3$ for glycine and lignin. respectively. The highest H2 production, 1.24 mmol was obtained for glycerol-SCWG with $Mn(NO_3)_2$. Conclusively, the addition of $Mn(NO_3)_2$ enhanced all model biomass gasification efficiency and increased the hydrogen production promoting the supercritical water reaction.