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Ultralow charge-transfer resistance with ultralow Pt loading for hydrogen evolution and oxidation using Ru@Pt core-shell nanocatalysts.

Wang JX, Zhang Y, Capuano CB, Ayers KE - Sci Rep (2015)

Bottom Line: In 1 M HClO4 at 23 °C, a CTR as low as 0.04 Ω cm(-2) was obtained with only 20 μg cm(-2) Pt and 11 μg cm(-2) Ru using the carbon-supported Ru@Pt with 1:1 Ru:Pt atomic ratio.Derived from temperature-dependent CTRs, the activation barrier of the Ru@Pt catalyst for the HER-HOR in acids is 0.2 eV or 19 kJ mol(-1).Using the Ru@Pt catalyst with total metal loadings <50 μg cm(-2) for the HER in proton-exchange-membrane water electrolyzers, we recorded uncompromised activity and durability compared to the baseline established with 3 mg cm(-2) Pt black.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973, USA.

ABSTRACT
We evaluated the activities of well-defined Ru@Pt core-shell nanocatalysts for hydrogen evolution and oxidation reactions (HER-HOR) using hanging strips of gas diffusion electrode (GDE) in solution cells. With gas transport limitation alleviated by micro-porous channels in the GDEs, the charge transfer resistances (CTRs) at the hydrogen reversible potential were conveniently determined from linear fit of ohmic-loss-corrected polarization curves. In 1 M HClO4 at 23 °C, a CTR as low as 0.04 Ω cm(-2) was obtained with only 20 μg cm(-2) Pt and 11 μg cm(-2) Ru using the carbon-supported Ru@Pt with 1:1 Ru:Pt atomic ratio. Derived from temperature-dependent CTRs, the activation barrier of the Ru@Pt catalyst for the HER-HOR in acids is 0.2 eV or 19 kJ mol(-1). Using the Ru@Pt catalyst with total metal loadings <50 μg cm(-2) for the HER in proton-exchange-membrane water electrolyzers, we recorded uncompromised activity and durability compared to the baseline established with 3 mg cm(-2) Pt black.

No MeSH data available.


Related in: MedlinePlus

Pt-loading-dependent HER-HOR CTR and cyclic voltammetry curves measured using hanging-strip GDEs.(a) CTRs measured in hydrogen saturated 1 M HClO4 at 23 °C for five Ru@Pt catalysts with the Pt:Ru atomic ratio ranging from 0.1 to 1.3 as a function of Pt loading. The black line is calculated using 0.4 (Ω cm2) divided by Pt loading LPt (μg cm−2). (b) iR-corrected voltammetry curves on the GDE strips for a Pt and a bilayer Ru@Pt1.0 catalysts.
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f2: Pt-loading-dependent HER-HOR CTR and cyclic voltammetry curves measured using hanging-strip GDEs.(a) CTRs measured in hydrogen saturated 1 M HClO4 at 23 °C for five Ru@Pt catalysts with the Pt:Ru atomic ratio ranging from 0.1 to 1.3 as a function of Pt loading. The black line is calculated using 0.4 (Ω cm2) divided by Pt loading LPt (μg cm−2). (b) iR-corrected voltammetry curves on the GDE strips for a Pt and a bilayer Ru@Pt1.0 catalysts.

Mentions: To determine the optimal Pt:Ru atomic ratio in the Ru@Pt catalysts and the minimal Pt loading that is required for top performance, we measured the Pt-loading-dependent CTRs for five Ru@Pt catalysts with the Pt:Ru atomic ratios ranging from 0.1 to 1.3. In our previous studies, monolayer and bilayer Pt shells, respectively, were found for the Ru@Pt catalysts synthesized using 0.5 and 1.0 Pt:Ru atomic ratio9. With Pt loadings up to 25 μg cm−2, the best performance often was attained with the bilayer Ru@Pt1.0 catalyst (red dots in Fig. 2a). The trend is illustrated by a calculated curve using CTR (Ω cm2) = 0.4/Pt loading (μg cm−2), that is, ≤0.04 Ω cm2 can be obtained with ≥10 μg cm−2 Pt. Due to the uncertainty level in determining the HFR (see the noise in Fig. 1d for highly active samples), we consider 0.04 Ω cm2 as the minimal value that can be unambiguously determined.


Ultralow charge-transfer resistance with ultralow Pt loading for hydrogen evolution and oxidation using Ru@Pt core-shell nanocatalysts.

Wang JX, Zhang Y, Capuano CB, Ayers KE - Sci Rep (2015)

Pt-loading-dependent HER-HOR CTR and cyclic voltammetry curves measured using hanging-strip GDEs.(a) CTRs measured in hydrogen saturated 1 M HClO4 at 23 °C for five Ru@Pt catalysts with the Pt:Ru atomic ratio ranging from 0.1 to 1.3 as a function of Pt loading. The black line is calculated using 0.4 (Ω cm2) divided by Pt loading LPt (μg cm−2). (b) iR-corrected voltammetry curves on the GDE strips for a Pt and a bilayer Ru@Pt1.0 catalysts.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507399&req=5

f2: Pt-loading-dependent HER-HOR CTR and cyclic voltammetry curves measured using hanging-strip GDEs.(a) CTRs measured in hydrogen saturated 1 M HClO4 at 23 °C for five Ru@Pt catalysts with the Pt:Ru atomic ratio ranging from 0.1 to 1.3 as a function of Pt loading. The black line is calculated using 0.4 (Ω cm2) divided by Pt loading LPt (μg cm−2). (b) iR-corrected voltammetry curves on the GDE strips for a Pt and a bilayer Ru@Pt1.0 catalysts.
Mentions: To determine the optimal Pt:Ru atomic ratio in the Ru@Pt catalysts and the minimal Pt loading that is required for top performance, we measured the Pt-loading-dependent CTRs for five Ru@Pt catalysts with the Pt:Ru atomic ratios ranging from 0.1 to 1.3. In our previous studies, monolayer and bilayer Pt shells, respectively, were found for the Ru@Pt catalysts synthesized using 0.5 and 1.0 Pt:Ru atomic ratio9. With Pt loadings up to 25 μg cm−2, the best performance often was attained with the bilayer Ru@Pt1.0 catalyst (red dots in Fig. 2a). The trend is illustrated by a calculated curve using CTR (Ω cm2) = 0.4/Pt loading (μg cm−2), that is, ≤0.04 Ω cm2 can be obtained with ≥10 μg cm−2 Pt. Due to the uncertainty level in determining the HFR (see the noise in Fig. 1d for highly active samples), we consider 0.04 Ω cm2 as the minimal value that can be unambiguously determined.

Bottom Line: In 1 M HClO4 at 23 °C, a CTR as low as 0.04 Ω cm(-2) was obtained with only 20 μg cm(-2) Pt and 11 μg cm(-2) Ru using the carbon-supported Ru@Pt with 1:1 Ru:Pt atomic ratio.Derived from temperature-dependent CTRs, the activation barrier of the Ru@Pt catalyst for the HER-HOR in acids is 0.2 eV or 19 kJ mol(-1).Using the Ru@Pt catalyst with total metal loadings <50 μg cm(-2) for the HER in proton-exchange-membrane water electrolyzers, we recorded uncompromised activity and durability compared to the baseline established with 3 mg cm(-2) Pt black.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973, USA.

ABSTRACT
We evaluated the activities of well-defined Ru@Pt core-shell nanocatalysts for hydrogen evolution and oxidation reactions (HER-HOR) using hanging strips of gas diffusion electrode (GDE) in solution cells. With gas transport limitation alleviated by micro-porous channels in the GDEs, the charge transfer resistances (CTRs) at the hydrogen reversible potential were conveniently determined from linear fit of ohmic-loss-corrected polarization curves. In 1 M HClO4 at 23 °C, a CTR as low as 0.04 Ω cm(-2) was obtained with only 20 μg cm(-2) Pt and 11 μg cm(-2) Ru using the carbon-supported Ru@Pt with 1:1 Ru:Pt atomic ratio. Derived from temperature-dependent CTRs, the activation barrier of the Ru@Pt catalyst for the HER-HOR in acids is 0.2 eV or 19 kJ mol(-1). Using the Ru@Pt catalyst with total metal loadings <50 μg cm(-2) for the HER in proton-exchange-membrane water electrolyzers, we recorded uncompromised activity and durability compared to the baseline established with 3 mg cm(-2) Pt black.

No MeSH data available.


Related in: MedlinePlus