<br>零电荷电势的溶剂依赖性的起源,JACS Au

当前位置： X-MOL 学术 › JACS Au › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

零电荷电势的溶剂依赖性的起源
JACS Au ( IF 8.5 ) Pub Date : 2023-11-15 , DOI: 10.1021/jacsau.3c00552
Weiqiang Tang _{1,

2} , Shuangliang Zhao _{1,

3} , Jun Huang _{2,

4}

Affiliation

Au(111)-KPF ₆界面的基本性质，特别是零电荷电势 (PZC)，在溶剂之间表现出明显的变化，但其起源在很大程度上仍然难以捉摸。在这项研究中，我们的目标是将溶剂依赖性与异质介电介质中金属-溶液界面处发生的电子溢出的微观现象联系起来。为了解决在恒定电势条件下描述溶剂调制电子溢出的挑战，我们采用半经典函数方法并通过第一原理计算和实验数据对其进行参数化。我们发现，控制这种现象的关键变量是金属边缘上方约 2.5 Å 区域内的局部介电常数。较高的局部介电常数一方面有利于电子溢出，从而往往会增加 PZC，另一方面会增强对电子电荷的屏蔽，从而往往会降低 PZC。这些双重效应导致 PZC 和局部介电常数之间存在非单调关系。此外，我们的研究结果表明，电子溢出会在电极电位处产生电容峰值，该电容峰值比浓溶液中的 PZC 更负。这一观察结果与预测峰值精确出现在 PZC 的经典模型形成鲜明对比。为了阐明电子溢出对总电容的贡献，我们将总电容分解为金属的量子电容C _q 、电解质溶液的经典电容C _c和考虑电子-离子相关性的电容C _qc 。我们的计算表明，由于在更负的电势下促进了电子溢出， C _qc为负。我们的工作不仅揭示了局部介电常数在调节电子溢出方面的重要性，而且还提出了一种可行的理论方法来研究操作条件下溶剂对电化学界面的影响。

"点击查看英文标题和摘要"

Origin of Solvent Dependency of the Potential of Zero Charge

Fundamental properties of the Au(111)–KPF₆ interface, particularly the potential of zero charge (PZC), exhibit pronounced variations among solvents, yet the origin remains largely elusive. In this study, we aim to link the solvent dependency to the microscopic phenomenon of electron spillover occurring at the metal–solution interface in heterogeneous dielectric media. Addressing the challenge of describing the solvent-modulated electron spillover under constant potential conditions, we adopt a semiclassical functional approach and parametrize it with first-principles calculations and experimental data. We unveil that the key variable governing this phenomenon is the local permittivity within the region approximately 2.5 Å above the metal edge. A higher local permittivity facilitates the electron spillover that tends to increase the PZC on the one hand and enhances the screening of the electronic charge that tends to decrease the PZC on the other. These dual effect lead to a nonmonotonic relationship between the PZC and the local permittivity. Moreover, our findings reveal that the electron spillover induces a capacitance peak at electrode potentials that are more negative than the PZC in concentrated solutions. This observation contrasts classical models predicting the peak to occur precisely at the PZC. To elucidate the contribution of electron spillover to the total capacitance, we decompose the total capacitance into a quantum capacitance of the metal C_q, a classical capacitance of electrolyte solution C_c, and a capacitance C_qc accounting for electron–ion correlations. Our calculations reveal that C_qc is negative due to the promoted electron spillover at more negative potentials. Our work not only reveals the importance of local permittivity in tuning the electron spillover but also presents a viable theoretical approach to study solvent effects on electrochemical interfaces under operating conditions.

更新日期：2023-11-15

点击分享查看原文

点击收藏

公开下载

阅读更多本刊新发论文