Interfacial water reorganization as a pH-dependent descriptor of the hydrogen evolution rate on platinum electrodes

Abstract

The hydrogen evolution on platinum is a milestone reaction in electrocatalysis as well as an important reaction towards sustainable energy storage. Remarkably, the pH dependent kinetics of this reaction is not yet fully understood. Here, we present a detailed kinetic study of the hydrogen adsorption and evolution reaction on Pt(111) in a wide pH range. Impedance and Tafel slope measurements show that the hydrogen adsorption and hydrogen evolution are both slow in alkaline media, which is consistent with the observation of a shift in the rate-determining step for H2 evolution.Adding nickel to the Pt(111) surface lowers the barrier for the hydrogen adsorption rate in alkaline solutions and thereby enhances the hydrogen evolution rate. These observations are explained by a new model which highlights the role of the reorganization of interfacial water to accommodate charge transfer through the electric double layer, the energetics of which is controlled by how strongly water interacts with the interfacial field. The new model is supported by laser-induced temperature-jump measurements. Our model sheds new light on the origin of the slow kinetics for the hydrogen evolution reaction in alkaline media.

Lateral Adsorbate Interactions Inhibit HCOO− while Promoting CO Selectivity for CO2 Electrocatalysis on Silver

“…V *H is therefore expected to play an important role in the formation of higher electron reduction products of CO 2 ER and this analysis can potentially be useful for studying catalysts such as Cu where these reaction steps become prominent. [16] Based on the results in Figure 2, we show that there is asignificant energy barrier for the formation of the CO pathway intermediate *COOH, whereas *OCHO is expected to form readily on the Ag(110) surface in the presence of *H. To validate our theoretical findings,p reliminary in situ electrochemical SERS measurements were performed to probe polycrystalline Ag catalyst surface during CO 2 ER in 0.05 m Li 2 B 4 O 7 [17] saturated with CO 2 ,w ith ab ulk pH of 6.1 (Experimental details in Supporting Information). [14] Climbing image nudged elastic band (CI-NEB) calculations were performed to estimate the height of the activation barriers based on the reaction path analysis presented in Figure 1( see Computational Details section in Supporting Information).…”

Iridium‐Based Multimetallic Porous Hollow Nanocrystals for Efficient Overall‐Water‐Splitting Catalysis

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Electrochemical water splitting is considered as the sustainable, environmentalfriendly and low-cost technology for renewable energy supplement. [6,7] Pt and Ir (or Ru)-based nanocrystals are the best metal catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, in overall water splitting device, [8][9][10][11] but unfortunately, their further applications are still hindered by their poor intrinsic electrocatalytic activities resulting from sluggish kinetics of HER and OER. [6,7] Pt and Ir (or Ru)-based nanocrystals are the best metal catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, in overall water splitting device, [8][9][10][11] but unfortunately, their further applications are still hindered by their poor intrinsic electrocatalytic activities resulting from sluggish kinetics of HER and OER.

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Co‐adsorption of Cations as the Cause of the Apparent pH Dependence of Hydrogen Adsorption on a Stepped Platinum Single‐Crystal Electrode

“…However, HER/HOR shows the same pH dependence on a step-free Pt(111) electrode, so that there cannot be a chemical relation between these two observations, at least not for Pt(111) [12] . Still, the cation may block or inhibit active sites [13] , alter the structure of near-surface water, or adsorbed hydroxyl (*OH) may be involved in the hydrogen oxidation/evolution and other electrocatalytic reaction mechanisms as the cation alters its structure and stability.…”