Increasing the rate of the hydrogen evolution reaction in neutral water with protic buffer electrolytes
Increasing the rate of the hydrogen evolution reaction in neutral water with protic buffer electrolytes
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DOI：
10.1073/pnas.2012085117
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发表时间：
2020-12-29
影响因子：
11.1
通讯作者：
Lichtenberger, Dennis L.
中科院分区：
文献类型：
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作者：
Clary, Kayla E.;Karayilan, Metin;Lichtenberger, Dennis L.
在中性pH水中电催化生成H-2具有挑战性，其中析氢反应（HER）的高催化电流对质子源和溶液特性特别敏感。在pH值为7的三（羟甲基）氨基甲烷（tris）溶液中加入[2Fe-2S]-金属聚合物电催化剂，其催化电流密度比传统的磷酸钠溶液或氯化钾（KCl）电解质溶液大两个数量级左右。对于平面多晶Pt圆盘电极，与磷酸钠溶液相比，pH为7的TRIS溶液在电流密度超过100 mA/cm(2)时，H-2生成的催化电流密度增加了50 mA/cm(2)。作为本研究的一个特点，TRIS不仅作为质子的主要来源和pH的缓冲，而且质子化的TRIS （[TRIS- h](+)）也是电解质的唯一阳离子。同时作为质子源、缓冲液和唯一电解质的物质称为质子缓冲电解质（PBE）。讨论了提高金属聚合物和铂催化剂HER率的TRIS PBE的构效关系。这些结果表明，适当设计的PBEs可以提高任何均相或非均相电催化剂体系的HER率。一般准则的选择PBE，以提高催化电流密度的HER系统提供。
Electrocatalytic generation of H-2 is challenging in neutral pH water, where high catalytic currents for the hydrogen evolution reaction (HER) are particularly sensitive to the proton source and solution characteristics. A tris(hydroxymethyl)aminomethane (TRIS) solution at pH 7 with a [2Fe-2S]-metallopolymer electrocatalyst gave catalytic current densities around two orders of magnitude greater than either a more conventional sodium phosphate solution or a potassium chloride (KCl) electrolyte solution. For a planar polycrystalline Pt disk electrode, a TRIS solution at pH 7 increased the catalytic current densities for H-2 generation by 50 mA/cm(2) at current densities over 100 mA/cm(2) compared to a sodium phosphate solution. As a special feature of this study, TRIS is acting not only as the primary source of protons and the buffer of the pH, but the protonated TRIS ([TRIS-H](+)) is also the sole cation of the electrolyte. A species that is simultaneously the proton source, buffer, and sole electrolyte is termed a protic buffer electrolyte (PBE). The structure-activity relationships of the TRIS PBE that increase the HER rate of the metallopolymer and platinum catalysts are discussed. These results suggest that appropriately designed PBEs can improve HER rates of any homogeneous or heterogeneous electrocatalyst system. General guidelines for selecting a PBE to improve the catalytic current density of HER systems are offered.