Ir 전극 계면에서 위상이동 방법 및 상관계수를 이용한 수소의 흡착동온식 결정

전상규,Jeon, Sang-K. 한국전기화학회 2007 한국전기화학회지 Vol.10 No.2

백금족/수용액 계면에서 Langmuir, Frumkin, Temkin 흡착등온식(${\theta}\;vs.\;E$)을 결정하기 위해 최적중간주파수 일 때 위상이동($0^{\circ}{\leq}-{\varphi}{\leq}90^{\circ}$) 거동($-{\varphi}\;vs.\;E$)과 표면피복율($1{\geq}{\theta}{\geq}0$) 거동(${\theta}\;vs.\;E$) 사이의 선형 관계식 연구에 관한 위상이동 방법 및 상관계수를 제안하고 증명하였다. Ir/0.1 M KOH수용액 계면에서 음극 $H_2$ 발생 반응에 관한 수소의 Langmuir 및 Temkin 흡착등온식(${\theta}\;vs.\;E$), 평형상수(Langmuir 흡착등온식: $K=3.3{\times}10^{-4}mol^{-1}$, Temkin 흡착등온식: $K=3.3{\times}10^{-3}{\exp}(-4.6{\theta})\;mol^{-1}$), 상호작용 파라미터(Temkin 흡착등온식: g=4.6), 표준자유에너지($K=3.3{\times}10^{-4}mol^{-1}$ 일 때 ${\Delta}G_{ads}^0=19.9kJ\;mol^{-1},\;K=3.3{\times}10^{-3}{\exp}(-4.6{\theta})\;mol^{-1}$ 및 $0.2<{\theta}<0.8$일 때 $16.5<{\Delta}G_{\theta}^0<23.3kJ\;mol^{-1}$)를 결정한다. 수소 흡착부위의 비균일 및 측 방향 상호작용 효과는 무시할 수 있다. ${\theta}$의 중간값 즉, $0.2<{\theta}<0.8$일 때 Langmuir 또는 Frumkin 흡착등온식과 상관관계에 있는 Temkin 흡착등온식은 상관계수를 이용하여 쉽게 결정할 수 있다. 위상이동 방법 및 상관계수는 흡착동온식(${\theta}\;vs.\;E$) 및 연관된 전극속도론과 열역학 파라미터(K, g, ${\Delta}G_{ads}^0, {\Delta}G_{\theta}^0$)를 결정하기 위한 정확하고 확실한 기술 및 방법이다. The phase-shift method and correlation constants for studying a linear relationship between the behavior ($-{\varphi}\;vs.\;E$) of the phase shift ($0^{\circ}{\leq}-{\varphi}{\leq}90^{\circ}$) for the optimum intermediate frequency and that (${\theta}\;vs.\;E$) of the fractional surface coverage ($1{\geq}\theta{\geq}0$) have been proposed and verified to determine the Langmuir, Frumkin, and Temkin adsorption isotherms (${\theta}\;vs.\;E$) at noble metal/aqueous electrolyte interfaces. At an Ir/0.1 M KOH aqueous electrolyte interface, the Langmuir and Temkin adsorption isotherms (${\theta}\;vs.\;E$), equilibrium constants ($K=3.3{\times}10^{-4}\;mol^{-1}$ for the Langmuir and $K=3.3{\times}10^{-3}{\exp}(-4.6{\theta})\;mol^{-1}$ for the Temkin adsorption isotherm), interaction parameter (g = 4.6 for the Temkin adsorption isotherm), and standard free energies (${\Delta}G_{ads}^0=19.9kJ\;mol^{-1}\;for\;K=3.3{\times}10^{-4}\;mol^{-1}$ and $16.5<{\Delta}G_{\theta}^0<23.3\;kJ\;mol^{-1}\;for\;K=3.3{\times}10^{-3}{\exp}(-4.6{\theta})\;mol^{-1}\;and\;0.2<\theta<0.8$) of H for the cathodic $H_2$ evolution reaction are determined using the phase-shift method and correlation constants. The inhomogeneous and lateral interaction effects on the adsorption of H are negligible. At the intermediate values of ${\theta},\;i.e,\;0.2<{\theta}<0.8$, the Temkin adsorption isotherm (${\theta}\;vs.\;E$) correlating with the Langmuir or the Frumkin adsorption isotherm (${\theta}\;vs.\;E$), and vice versa, is readily determined using the correlation constants. The phase-shift method and correlation constants are accurate and reliable techniques to determine the adsorption isotherms (${\theta}\;vs.\;E$) and related electrode kinetic and thermodynamic parameters(K, g, ${\Delta}G_{ads}^0, {\Delta}G_{\theta}^0$).

Determination of Adsorption Isotherms of Hydrogen on Zirconium in Sulfuric Acid Solution Using the Phase-Shift Method and Correlation Constants

천장호,천진영 한국전기화학회 2009 한국전기화학회지 Vol.12 No.1

The phase-shift method and correlation constants, i.e., the unique electrochemical impedance spectroscopy (EIS) techniques for studying the linear relationship between the behavior (−ϕ vs. E) of the phase shift (90° ≥ -ϕ≥ 0°) for the optimum intermediate frequency and that (θ vs. E) of the fractional surface coverage (0 ≤ θ ≤ 1), have been proposed and verified to determine the Langmuir, Frumkin, and Temkin adsorption isotherms of H and related electrode kinetic and thermodynamic parameters at noble metal (alloy)/aqueous solution interfaces. At a Zr/0.2 M H2SO4 aqueous solution interface, the Frumkin and Temkin adsorption isotherms (θ vs. E), equilibrium constants (K = 1.401 × 10-17 exp(-3.5θ) mol-1 for the Frumkin and K = 1.401 × 10-16 exp(-8.1θ) mol-1 for the Temkin adsorption isotherm), interaction parameters (g = 3.5 for the Frumkin and g = 8.1 for the Temkin adsorption isotherm), rates of change of the standard free energy (r = 8.7 kJ mol-1 for g = 3.5 and r = 20 kJ mol-1 for g = 8.1) of H with θ, and standard free energies (96.13≤ΔG<수식> ≤ 104.8 kJ mol-1 for K= 1.401 × 10-17 exp(-3.5θ) mol-1 and 0 ≤ θ ≤ 1 and 94.44 < ΔG<수식> < 106.5 kJ mol-1 for K= 1.401×10-16 exp(-8.1θ) mol-1 and 0.2 < θ < 0.8) of H are determined using the phase-shift method and correlation constants. At 0.2 < θ < 0.8, the Temkin adsorption isotherm correlating with the Frumkin adsorption isotherm, and vice versa, is readily determined using the correlation constants. The phase-shift method and correlation constants are probably the most accurate, useful, and effective ways to determine the adsorption isotherms of H and related electrode kinetic and thermodynamic parameters at highly corrosion-resistant metal/aqueous solution interfaces.

Determination of Adsorption Isotherms of Hydrogen on Zirconium in Sulfuric Acid Solution Using the Phase-Shift Method and Correlation Constants

Chun, Jang-H.,Chun, Jin-Y. The Korean Electrochemical Society 2009 한국전기화학회지 Vol.12 No.1

The phase-shift method and correlation constants, i.e., the unique electrochemical impedance spectroscopy (EIS) techniques for studying the linear relationship between the behavior ($-{\varphi}$ vs. E) of the phase shift ($90^{\circ}{\geq}-{\varphi}{\geq}0^{\circ}$) for the optimum intermediate frequency and that ($\theta$ vs. E) of the fractional surface coverage ($0{\leq}{\theta}{\leq}1$), have been proposed and verified to determine the Langmuir, Frumkin, and Temkin adsorption isotherms of H and related electrode kinetic and thermodynamic parameters at noble metal (alloy)/aqueous solution interfaces. At a Zr/0.2 M ${H_2}{SO_4}$ aqueous solution interface, the Frumkin and Temkin adsorption isotherms ($\theta$ vs. E), equilibrium constants (K = $1.401{\times}10^{-17}\exp(-3.5{\theta})mol^{-1}$ for the Frumkin and K = $1.401{\times}10^{-16}\exp(8.1{\theta})mol^{-1}$ for the Temkin adsorption isotherm), interaction parameters (g = 3.5 for the Frumkin and g = 8.1 for the Temkin adsorption isotherm), rates of change of the standard free energy (r = $8.7\;kJ\;mol^{-1}$ for g = 3.5 and r = $20\;kJ\;mol^{-1}$ for g = 8.1) of H with $\theta$, and standard free energies ($96.13{\leq}{\Delta}G^0_{\theta}{\leq}104.8\;kJ\;mol^{-1}$ for K = $1.401{\times}10^{-17}\exp(-3.5{\theta})mol^{-1}$ and $0{\leq}{\theta}{\leq}1$ and ($94.44<{\Delta}G^0_{\theta}<106.5\;kJ\;mol^{-1}$ for K = $1.401{\times}10^{-16}\exp(-8.1{\theta})mol^{-1}$ and $0.2<{\theta}<0.8$) of H are determined using the phase-shift method and correlation constants. At 0.2 < $\theta$ < 0.8, the Temkin adsorption isotherm correlating with the Frumkin adsorption isotherm, and vice versa, is readily determined using the correlation constants. The phase-shift method and correlation constants are probably the most accurate, useful, and effective ways to determine the adsorption isotherms of H and related electrode kinetic and thermodynamic parameters at highly corrosion-resistant metal/aqueous solution interfaces.

Determination of the Frumkin and Temkin Adsorption Isotherms of Hydrogen at Nickel/Acidic and Alkaline Aqueous Solution Interfaces Using the Phase-Shift Method and Correlation Constants

Chun, Jang-H. The Korean Electrochemical Society 2012 한국전기화학회지 Vol.15 No.1

The phase-shift method and correlation constants, which are unique electrochemical impedance spectroscopy techniques for studying the linear relationship between the phase shift ($90^{\circ}{\geq}-{\varphi}{\geq}0^{\circ}$) vs. potential (E) behavior for the optimum intermediate frequency ($f_o$) and the fractional surface coverage ($0{\leq}{\theta}{\leq}1$) vs. E behavior, are proposed and verified to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and the related electrode kinetic and thermodynamic parameters. At Ni/0.5 M $H_2SO_4$ and 0.1M LiOH aqueous solution interfaces, the Frumkin and Temkin adsorption isotherms (${\theta}$ vs. E) of H for the cathodic hydrogen ($H_2$) evolution, interaction parameters (g), equilibrium constants (K), standard Gibbs energies (${\Delta}G^0_{\theta}$) of H adsorption, and rates of change (r) of ${\Delta}G^0_{\theta}$ with ${\theta}$ have been determined using the phase-shift method and correlation constants. A lateral repulsive interaction (g>0) between the adsorbed H species appears. The value of K in the alkaline aqueous solution is much greater than that in the acidic aqueous solution.

Determination of the Frumkin and Temkin Adsorption Isotherms of Hydrogen at Nickel/Acidic and Alkaline Aqueous Solution Interfaces Using the Phase-Shift Method and Correlation Constants

천장호 한국전기화학회 2012 한국전기화학회지 Vol.15 No.1

The phase-shift method and correlation constants, which are unique electrochemical impedance spectroscopy techniques for studying the linear relationship between the phase shift (90o ≥ −ϕ ≥ 0o) vs. potential (E) behavior for the optimum intermediate frequency (fo) and the fractional surface coverage (0 ≤ θ ≤ 1) vs. E behavior, are proposed and verified to determine the Frumkin, Langmuir, and Temkin adsorption isotherms and the related electrode kinetic and thermodynamic parameters. At Ni/0.5 M H2SO4 and 0.1M LiOH aqueous solution interfaces,the Frumkin and Temkin adsorption isotherms (θ vs. E) of H for the cathodic hydrogen (H2)evolution, interaction parameters (g), equilibrium constants (K), standard Gibbs energies (ΔGθo)of H adsorption, and rates of change (r) of ΔGθo with θ have been determined using the phaseshift method and correlation constants. A lateral repulsive interaction (g > 0) between the adsorbed H species appears. The value of K in the alkaline aqueous solution is much greater than that in the acidic aqueous solution.

지반조건에 따른 유전상수 변화에 관한 연구

조진우(Cho, Jinwoo),조원범(Cho, Wonbeom),김진만(Kim, Jinman),최봉혁(Choi, Bonghyuck) 한국지반환경공학회 2012 한국지반환경공학회논문집 Vol.13 No.12

본 논문에서는 TDR 장비를 사용하여 지반특성에 따라 변화하는 유전상수를 측정하였으며, 지반의 함수비 및 밀도와의 상관성을 분석하였다. 또한, 유전상수를 이용한 지중 공동탐사기법의 적용성을 평가하기 위하여 공동의 크기에 따른 유전상수의 변화 정도를 측정하였다. 실험결과 지반의 유전상수는 함수비와 밀도가 증가함에 따라 선형적인 증가 경향을 나타내는 것으로 평가되었으며, 일정한 관계식으로 표현할 수 있었다. 또한, 지반의 유전상수는 공동의 크기에 따라 일정한 경향을 나타내며 변화하는 것으로 평가되었다. TDR 기법을 사용하여 측정된 유전상수값은 지반의 함수비, 밀도와 일정한 상관관계를 나타내고 있음을 확인하였으며, 지중 공동탐사에 관한 기초자료로서 활용할 수 있을 것으로 판단된다. In this study, dielectrical constant of the ground was measured using TDR method and correlated with water contents and density of ground. In order to evaluate the applicability as a cavity exploration, model experiments were carried out to analyze the effects of cavity size on the dielectrical constant. Test result indicated that dielectrical constant of the ground tended to linearly increase with the increase in water contents and density, which can be represented in a certain relational expression. Also, the dielectrical constant of ground varied sensitively with the cavity size of ground. The results conclude that the dielectrical constant, water contents and density of the ground proved to have a correlation among them, and the dielectrical constant is expected to be a basic data on cavity exploration.

Ab initio MRCI+Q Investigations of Spectroscopic Properties of Several Low-lying Electronic States of S₂⁺ Cation

Li, Rui,Zhai, Zhen,Zhang, Xiaomei,Liu, Tao,Jin, Mingxing,Xu, Haifeng,Yan, Bing Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.5

The complete active space self-consist field method followed by the internally contracted multireference configuration interaction method has been used to compute the potential energy curves of $X^2\prod_g$, $a^4\prod_u$, $A^2\prod_u$, $b^4\sum_{g}^{-}$, and $B^2\sum_{g}^{-}$ states of $S{_2}^+$ cation with large correlation-consistent basis sets. Utilizing the potential energy curves computed with different basis sets, the spectroscopic parameters of these states were evaluated. Finally, the transition dipole moment and the Franck-Condon factors of the transition from $A^2\prod_u$ to $X^2\prod_g$ were evaluated. The radiative lifetime of $A^2\prod_u$ is calculated to be 887 ns, which is in good agreement with experimental value of $805{\pm}10$ ns.

Ab initio MRCI+Q Investigations of Spectroscopic Properties of Several Low-lying Electronic States of S2+ Cation

Rui Li,Zhen Zhai,Xiaomei Zhang,Tao Liu,Mingxing Jin,Haifeng Xu,Bing Yan 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.5

The complete active space self-consist field method followed by the internally contracted multireference configuration interaction method has been used to compute the potential energy curves of X2Πg, a4Πu, A2Πu, b4Σ− g, and B2Σ− g states of S2 + cation with large correlation-consistent basis sets. Utilizing the potential energy curves computed with different basis sets, the spectroscopic parameters of these states were evaluated. Finally, the transition dipole moment and the Franck-Condon factors of the transition from A2Πu to X2Πg were evaluated. The radiative lifetime of A2Πu is calculated to be 887 ns, which is in good agreement with experimental value of 805 ± 10 ns.

볼 베어링의 결함검출을 위한 Adaptive Line Enhancer의 적용

김영태,최만용,김기복,박해원,박정학,김종억,류준 한국공작기계학회 2005 한국생산제조학회지 Vol.14 No.2

The early detection of the bearing defects in rotating machinery is very important since the critical failure of bearing causes a machinery shutdown. However it is not easy to detect the vibration signal caused by the initial defects of bearing because of the high level of random noise. A signal processing technique, called the adaptive line enhancer(ALE) as one of adaptive filter, is used in this study. This technique is to eliminate random noise with little a prior knowledge of the noise and signal characteristics. Also we propose the optimal methods for selecting the three main ALE parameters such as correlation length, filter order and adaptation constant. Vibration signals for three abnormal bearings, including inner and outer raceways and ball defects, were acquired by Anderon(angular derivative of radius on) meter. The experimental results showed that ALE is very useful for detecting the bearing defective signals masked by random noise.

Constant Correlation Factors between Temkin and Langmuir or Frumkin Adsorption lsotherms at Poly-Pt, Re, and Ni/Aqueous Electrolyte Interfaces

천장호,전상규,천진영 한국전기화학회 2004 한국전기화학회지 Vol.7 No.4

The constant correlation factors between the Temkin and the Langmuir or the Frumkin adsorption isotherms of over-potentially deposited hydrogen (OPD H) for the cathodic H2 evolution reaction (HER) at poly-Pt and Re/0.5 M H2SO4 and poly-Ni/0.05 M KOH aqueous electrolyte interfaces have been experimentally and consistently found using the phase-shift method. At intermediate values of the fractional surface coverage (), i.e., 0.2 0.8, the Langmuir and Temkin adsorption isotherms of OPD H for the cathodic HER are correlated to each other even though the adsorption conditions or processes are different from each other. At the same range of , correspondingly, the Frumkin and Temkin adsorption isotherms of OPD H for the cathodic HER are correlated to each other. The equilibrium constants (Ko) for the Temkin adsorption isotherms ( vs. E) are consistently ca. 10 times greater than those (K, Ko) for the corresponding Langmuir or Frumkin adsorption isotherms ( vs. E). The interaction parameters (g) for the Temkin adsorption isotherms ( vs. E) are consistently ca. 4.6 greater than those (g) for the corresponding Langmuir or Frumkin adsorption isotherms ( vs. E). These numbers (10 times and 4.6) can be taken as constant correlation factors between the corresponding adsorption isotherms (Temkin, Langmuir, Frumkin) at the interfaces. The Temkin adsorption isotherm corresponding to the Langmuir or the Frumkin adsorption isotherm, and vice versa, can be effectively verified or confirmed using the constant correlation factors. Both the phase-shift method and constant correlation factors are useful and effective for determining or confirming the suitable adsorption isotherms (Temkin, Langmuir, Frumkin) of intermediates for sequential reactions in electrochemical systems.