Energetics of the Underpotential Deposition of Hydrogen on Platinum Electrodes I. Absence of Coadsorbed Species
Energetics of the Underpotential Deposition of Hydrogen on Platinum Electrodes I. Absence of Coadsorbed Species
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铂电极上氢的欠电位沉积的能量学 I. 不存在共吸附物质
DOI：
10.1149/1.1837955
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发表时间：
1997
影响因子：
3.9
通讯作者：
G. Jerkiewicz
中科院分区：
文献类型：
--
作者：
A. Zolfaghari;M. Chayer;G. Jerkiewicz
Research on the underpotential deposition of hydrogen (UPD H) on Pt electrodes by cyclic voltammetry in 0.05, 0.10, and 0.50 M aqueous H{sub 2}SO{sub 4} solutions at temperatures from 273 to 343 K shows that the adsorption-desorption profiles shift toward less positive values upon temperature (T) increase. Treatment of the experimental results based on a general electrochemical adsorption isotherm allows determination of {Delta}G{sub ads}{sup o} (H(UPD)) as a function of T and the H(UPD) surface coverage, {theta}{sub H(UPD)}; {Delta}G{sub ads}{sup o} (H(UPD)) varies from {minus}11 to {minus}25 kJ/mol. The relation between {Delta}G{sub ads}{sup o} (H(UPD)) and T for {theta}{sub H(UPD)} = const allows determination of {Delta}S{sub ads}{sup o} (H(UPD)), which is from {minus}40 to {minus}90 J/mol K. Subsequently, {Delta}H{sub ads}{sup o} (H(UPD)) is determined and varies from {minus}27 to {minus}46 kJ/mol. An analysis of the values of {Delta}H{sub ads}{sup o} (H(UPD)) and {Delta}S{sub ads}{sup o} (H(UPD)) leads to conclusion that the UPD H on Pt electrodes is an enthalpy-driven process. Knowledge of {Delta}H{sub ads}{sup o} (H(UPD)) permits determination of the bond energy between Pt and H(UPD), E(Pt-H(UPD)), which is from 245 to 265 kJ/mol. The value of E(Pt-H(UPD)) falls close to that of the bond energy between Pt and H(chem),more » E(Pt-H(chem)), which varies from 243 to 247 kJ/mol. Proximity of E(Pt-H(UPD)) to E(Pt-H(chem)) indicates that H(UPD), and H(chem) have a similar binding mechanism in presence of the electrified solid/liquid interface and under gas-phase conditions; it shows that H(UPD) and H(chem) might occupy the same adsorption sites, thus indicating that H(UPD), like H(chem), is strongly embedded in the surface lattice of the Pt substrate.« less
Research on the underpotential deposition of hydrogen (UPD H) on Pt electrodes by cyclic voltammetry in 0.05, 0.10, and 0.50 M aqueous H{sub 2}SO{sub 4} solutions at temperatures from 273 to 343 K shows that the adsorption-desorption profiles shift toward less positive values upon temperature (T) increase. Treatment of the experimental results based on a general electrochemical adsorption isotherm allows determination of {Delta}G{sub ads}{sup o} (H(UPD)) as a function of T and the H(UPD) surface coverage, {theta}{sub H(UPD)}; {Delta}G{sub ads}{sup o} (H(UPD)) varies from {minus}11 to {minus}25 kJ/mol. The relation between {Delta}G{sub ads}{sup o} (H(UPD)) and T for {theta}{sub H(UPD)} = const allows determination of {Delta}S{sub ads}{sup o} (H(UPD)), which is from {minus}40 to {minus}90 J/mol K. Subsequently, {Delta}H{sub ads}{sup o} (H(UPD)) is determined and varies from {minus}27 to {minus}46 kJ/mol. An analysis of the values of {Delta}H{sub ads}{sup o} (H(UPD)) and {Delta}S{sub ads}{sup o} (H(UPD)) leads to conclusion that the UPD H on Pt electrodes is an enthalpy-driven process. Knowledge of {Delta}H{sub ads}{sup o} (H(UPD)) permits determination of the bond energy between Pt and H(UPD), E(Pt-H(UPD)), which is from 245 to 265 kJ/mol. The value of E(Pt-H(UPD)) falls close to that of the bond energy between Pt and H(chem),more » E(Pt-H(chem)), which varies from 243 to 247 kJ/mol. Proximity of E(Pt-H(UPD)) to E(Pt-H(chem)) indicates that H(UPD), and H(chem) have a similar binding mechanism in presence of the electrified solid/liquid interface and under gas-phase conditions; it shows that H(UPD) and H(chem) might occupy the same adsorption sites, thus indicating that H(UPD), like H(chem), is strongly embedded in the surface lattice of the Pt substrate.« less