Ultrathin Silicon Oxide Overlayers Enable Selective Oxygen Evolution from Acidic and Unbuffered pH-Neutral Seawater
Ultrathin Silicon Oxide Overlayers Enable Selective Oxygen Evolution from Acidic and Unbuffered pH-Neutral Seawater
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DOI：
10.1021/acscatal.0c04343
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发表时间：
2021-01-12
期刊：
影响因子：
12.9
通讯作者：
Esposito, Daniel, V
中科院分区：
文献类型：
--
作者：
Bhardwaj, Amar A.;Vos, Johannes G.;Esposito, Daniel, V
在淡水稀缺和可再生电力充足的情况下，海水电解是生产清洁氢燃料的一种有吸引力的方法。然而，海水中的氯离子（Cl-）会加速电极的腐蚀，并参与不良的氯析出反应（CER）。这个问题在酸性条件下尤其严重，这种酸性条件是由于期望的析氧反应（OER）而在阳极自然产生的。在此，我们证明了模型铂阳极上的超薄氧化硅（SiOx）覆盖层在酸性和非缓冲ph中性电解质中都能非常有效地抑制0.6 M Cl-存在的CER，通过阻止Cl-向催化活性埋藏界面的运输，同时允许所需的析氧反应（OER）在那里发生。氯离子在SiOx膜层中的渗透性比在反渗透脱盐中使用的常规盐选择膜中的渗透性低3个数量级。在中等过电位下的时间电流测试中，覆盖层也表现出超过12小时的稳健稳定性。SiOx覆盖层在实现选择性和稳定的海水电解方面迈出了有希望的一步，而无需调整电解质的pH值。
Seawater electrolysis is an attractive approach for producing clean hydrogen fuel in scenarios where freshwater is scarce and renewable electricity is abundant. However, chloride ions (Cl-) in seawater can accelerate electrode corrosion and participate in the undesirable chlorine evolution reaction (CER). This problem is especially acute in acidic conditions that naturally arise at the anode as a result of the desired oxygen evolution reaction (OER). Herein, we demonstrate that ultrathin silicon oxide (SiOx) overlayers on model platinum anodes are highly effective at suppressing the CER in the presence of 0.6 M Cl- in both acidic and unbuffered pH-neutral electrolytes by blocking the transport of Cl- to the catalytically active buried interface while allowing the desired oxygen evolution reaction (OER) to occur there. The permeability of Cl- in SiOx overlayers is 3 orders of magnitude less than that of Cl- in a conventional salt-selective membrane used in reverse osmosis desalination. The overlayers also exhibit robust stability over 12 h in chronoamperometry tests at moderate overpotentials. SiOx overlayers demonstrate a promising step toward achieving selective and stable seawater electrolysis without the need to adjust the pH of the electrolyte.