Influence of Alkali Metal Cations on the Hydrogen Evolution Reaction Activity of Pt, Ir, Au, and Ag Electrodes in Alkaline Electrolytes

Abstract

Fundamental understanding of the influence of so‐called spectator electrolyte species on the catalytic activity of electrodes is considered as a relatively novel direction in electrocatalysis. Numerous recent examples show that seemingly inert electrolyte components drastically influence the performance of catalytic centers. Even alkali metal cations in aqueous electrolytes at high pH values can change the reaction turnover frequency by orders of magnitude, depending on their nature, from Li+ to Cs+. Here, we use several electrodes, namely Pt(polycrystalline), Pt(111), Pt(221), Ir(111), Au(111), and Ag(polycrystalline), in different alkali metal cation‐containing electrolytes to reveal their role in the hydrogen evolution reaction (HER). The HER activity trends of various Pt electrodes, irrespective of their surface structure, correlate with the hydration energy of the corresponding alkali metal cations present in the electrolyte (Li+>Na+>K+>Rb+>Cs+). The trend remains the same for the Ir(111), however, it is reversed for Au(111) and Ag(pc) electrocatalysts.

Revealing the nature of active sites in electrocatalysis

“…The electrolyte composition is another parameter that can substantially modulate the overall catalyst performance. 29,[105][106][107][108] The ORR activities of various single crystalline Pt electrodes in different alkaline solutions have been investigated by Garlyyev et al 109 Interestingly, the inuence of the alkali metal cations is surface structure sensitive. As shown in Fig.…”

Influence of Van der Waals Interactions on the Solvation Energies of Adsorbates at Pt‐Based Electrocatalysts

“…Depending on the desired level of accuracy, these concrete observations and our tabulated values can be used to rapidly incorporate solvation into models for electrocatalysis and liquid-phase catalysis.The solvation of adsorbates is becoming a topic of great interest in computational electrocatalysis in view of the current search for more realistic representations of electrode-electrolyte interfaces. Numerous recent experimental works show that solvent and/or electrolyte effects change the activity and selectivity of electrocatalysts for important reactions such as oxygen reduction, [1,2] hydrogen evolution, [3,4] CO 2 reduction, [5,6] and CO reduction. [7,8] In addition, computational works show that solvation and/or cation coadsorption modify the adsorption energies of reaction intermediates, [9][10][11][12][13] which may not only lead to changes in reaction pathways [14] but also to considerable differences in the calculated activity of electrocatalysts.…”

Prospects of Value‐Added Chemicals and Hydrogen via Electrolysis

“…In electrocatalytic reactions the overpotential is mainly governed by the electrocatalyst activity, which mainly depends on its surface structure and composition . Furthermore, in recent studies the rate of the reaction is shown to be largely influenced by the so‐called spectator species in the electrolyte . Thus, the composition of the solution needs to be carefully tailored.…”