Goyal Akansha, Koper Marc T M
Leiden Institute of Chemistry, Leiden University, PO Box 9502, 2300, RA, Leiden, The Netherlands.
Angew Chem Int Ed Engl. 2021 Jun 7;60(24):13452-13462. doi: 10.1002/anie.202102803. Epub 2021 May 7.
In this work we study the role of alkali metal cation concentration and electrolyte pH in altering the kinetics of the hydrogen evolution reaction (HER) at gold (Au) electrodes. We show that at moderately alkaline pH (pH 11), increasing the cation concentration significantly enhances the HER activity on Au electrodes (with a reaction order ≈0.5). Based on these results we suggest that cations play a central role in stabilizing the transition state of the rate-determining Volmer step by favorably interacting with the dissociating water molecule (*H-OH -cat ). Moreover, we show that increasing electrolyte pH (pH 10 to pH 13) tunes the local field strength, which in turn indirectly enhances the activity of HER by tuning the near-surface cation concentration. Interestingly, a too high near-surface cation concentration (at high pH and high cation concentration) leads to a lowering of the HER activity, which we ascribe to a blockage of the surface by near-surface cations.
在这项工作中，我们研究了碱金属阳离子浓度和电解质pH值在改变金（Au）电极上析氢反应（HER）动力学方面的作用。我们表明，在中等碱性pH值（pH 11）下，增加阳离子浓度会显著提高Au电极上的HER活性（反应级数≈0.5）。基于这些结果，我们认为阳离子通过与解离的水分子（*H-OH -cat）有利地相互作用，在稳定速率决定步骤Volmer步骤的过渡态中起着核心作用。此外，我们表明增加电解质pH值（pH 10至pH 13）会调节局部场强，进而通过调节近表面阳离子浓度间接提高HER的活性。有趣的是，过高的近表面阳离子浓度（在高pH值和高阳离子浓度下）会导致HER活性降低，我们将其归因于近表面阳离子对表面的阻塞。
