NaOH/KOH 水溶液的 pH 值：电催化的关键和重要参数,ACS Energy Letters

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NaOH/KOH 水溶液的 pH 值：电催化的关键和重要参数
ACS Energy Letters ( IF 19.3 ) Pub Date : 2021-09-15 , DOI: 10.1021/acsenergylett.1c01693
J. Niklas Hausmann ₁ , Brian Traynor ₂ , Rupert J. Myers ₃ , Matthias Driess ₁ , Prashanth W. Menezes ₁

Affiliation

图 1. 左：电化学储能的能量示意图，以析氢和氧化反应为例（蓝色）。右图：作为浓度和温度函数的 1 M KOH 的 pH 依赖性。红色条表示电催化文献中报道的 25 °C 和 1 M 下的 pH 值范围（见表 S1）。如果使用 13.5 或 14 的 pH 值，是否存在显着的效率差异？为什么报告了 25 °C 下 1 M KOH 的不同 pH 值？可以确定 (Na/K)OH 水溶液的绝对 pH 值吗？是否可以提供合理的 (Na/K)OH 水溶液（0-100 °C，0-10 M）的 pH 值，以允许省略电催化中不一致的实验 pH 测定？图 2. 0.1、1 和 6 mol/kg NaOH 水溶液（左）和 KOH（右）的 pH 值作为温度的函数，使用方程 5 计算，并基于 Åkerlöf 和同事的活动系数。虚线表示水和 Na/KOH 的活度系数为 1 的常见假设，这相当于直接使用浓度计算 pH 值。支持信息中的电子表格可用于计算 0–10 M (Na/K)OH 浓度范围内的 pH 值_(aq)和温度范围 0–100 °C。在大约 4.5 和 6 mol/kg 时，NaOH 和 KOH 水溶液的电导率分别达到最大值。支持信息中的电子表格可用于计算浓度范围 0–10 M (Na/K)OH _(aq)和温度范围 0–100 °C的 pH 值和其他数据。支持信息可在 https://pubs.acs.org/doi/10.1021/acsenergylett.1c01693 免费获取。

表 S1，报告了 1 M KOH 的各种 pH 值，图 S1，活性系数与温度和摩尔浓度的关系 (PDF)
用于 pH 计算的 Excel 电子表格 (XLSX)

表 S1，包含 1 M KOH 的各种报告 pH 值，以及图 S1，活度系数与温度和摩尔浓度的关系 (PDF) 用于 pH 计算的 Excel 电子表格 (XLSX) 大多数电子支持信息文件无需订阅 ACS 网络版即可获得. 此类文件可以按文章下载用于研究用途（如果相关文章有公共使用许可，则该许可可能允许其他用途）。可以通过 RightsLink 许可系统的请求从 ACS 获得许可用于其他用途：http://pubs.acs.org/page/copyright/permissions.html。本观点中表达的观点是作者的观点，不一定是 ACS 的观点。由 Deutsche Forschungsgemeinschaft (DFG, 德国研究基金会）根据德国卓越战略 – EXC 2008/1-390540038 – UniSysCat。JNH 归功于柏林爱因斯坦基金会/EC² /BIG-NSE 博士奖学金。导致本出版物的研究受益于 EPSRC 拨款编号 EP/R010161/1 和 UKCRIC 协调节点的支持，EPSRC 拨款编号 EP/R017727/1，该基金资助 UKCRIC 的持续协调。英国电信感谢 NSF CAREER #1751925 的支持。本文引用了 31 篇其他出版物。对于电催化质子耦合反应，pH 依赖性等价于 ( n _{H ⁺} / n _{e ^–} ) × 0.059 V，其中n _e–和n _{H ⁺}分别是反应中转移的电子数和质子数。

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The pH of Aqueous NaOH/KOH Solutions: A Critical and Non-trivial Parameter for Electrocatalysis

Figure 1. Left: Schematic energy diagram for electrochemical energy storage with the hydrogen evolution and oxidation reaction as examples (blue). Right: pH dependency of 1 M KOH as a function of concentration and temperature. The red bar marks the pH value range reported in the electrocatalysis literature at 25 °C and 1 M (see Table S1). Is there a significant efficiency difference if a pH value of 13.5 or 14 is used? Why have different pH values for 1 M KOH at 25 °C been reported? Can absolute pH values of aqueous (Na/K)OH solutions be determined? Can reasonable pH values of aqueous (Na/K)OH solutions (0–100 °C, 0–10 M) be provided that allow omitting inconsistent experimental pH determinations in electrocatalysis? Figure 2. pH values of 0.1, 1, and 6 mol/kg aqueous NaOH (left) and KOH (right) solutions as functions of temperature, calculated with eq 5 and based on Åkerlöf and co-workers’ activity coefficient. The dashed lines are for the common assumption that the activity coefficients of water and Na/KOH are 1, which is equivalent to using concentrations directly for pH calculations. The spreadsheet in the Supporting Information can be used to calculate the pH for the concentration range 0–10 M (Na/K)OH_(aq) and the temperature range 0–100 °C. At around 4.5 and 6 mol/kg the electric conductivities of aqueous NaOH and KOH are at their maxima, respectively. The spreadsheet in the Supporting Information can be used to calculate the pH and other data for the concentration range 0–10 M (Na/K)OH_(aq) and the temperature range 0–100 °C. The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsenergylett.1c01693.

Table S1, with various reported pH values for 1 M KOH, and Figure S1, with activity coefficients plotted against temperature and molality (PDF)
Excel spreadsheet for pH calculations (XLSX)

Table S1, with various reported pH values for 1 M KOH, and Figure S1, with activity coefficients plotted against temperature and molality (PDF) Excel spreadsheet for pH calculations (XLSX) Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html. Views expressed in this Viewpoint are those of the authors and not necessarily the views of the ACS. Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC 2008/1-390540038 – UniSysCat. J.N.H. is indebted to the Einstein Foundation Berlin/EC²/BIG-NSE for a Ph.D. fellowship. The research leading to this publication benefitted from EPSRC funding under Grant No. EP/R010161/1, and from support from the UKCRIC Coordination Node, EPSRC Grant No. EP/R017727/1, which funds UKCRIC’s ongoing coordination. B.T. acknowledges support from NSF CAREER #1751925. This article references 31 other publications. For electrocatalytic proton-coupled reactions, the pH dependency is equivalent to the term (n_H⁺/n_e^–) × 0.059 V, where n_e– and n_H⁺ are the number of electrons and protons transferred in the reaction, respectively.

更新日期：2021-10-08

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