Low pH Electrolytic Water Splitting Using Earth-Abundant Metastable Catalysts That Self-Assemble in Situ
Low pH Electrolytic Water Splitting Using Earth-Abundant Metastable Catalysts That Self-Assemble in Situ
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DOI：
10.1021/ja5003197
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发表时间：
2014-02-26
影响因子：
15
通讯作者：
Cronin, Leroy
中科院分区：
文献类型：
--
作者：
Bloor, Leanne G.;Molina, Pedro I.;Cronin, Leroy
在低pH条件下电解水的典型催化剂是基于贵金属（阴极为Pt，阳极为IrO2或RuO2）。然而，这些金属既稀有又昂贵，因此，如果要更广泛地使用电解生产的氢，就需要更低的成本和更丰富的催化剂。这里,我们表明,electrode-film形成从第一行过渡金属离子的水溶液在pH值1.6可以诱导作用下一个适当的细胞偏见和钴的细胞在超过2 V电压导致的形成一对催化剂显示功能稳定氧进化和质子减少超过24小时,我们表明,这些电影是亚稳,如果打开电路,随着O-2和H-2的析出，它们重新溶解到电解液中，因此，进入系统的电荷的总体法拉第效率与获得的气体量对于O-2和H-2接近一致。这项工作强调了第一行过渡金属通过利用而不是试图避免催化剂在所使用的低ph值下溶解的自然倾向，在酸性介质中介导非均相电解水分裂的能力。反过来，我们希望这将鼓励其他人研究基于丰富元素的亚稳态电催化剂在一系列反应中的前景，这些反应传统上由于它们在普遍条件下的不稳定性而被忽视。
Typical catalysts for the electrolysis of water at low pH are based on precious metals (Pt for the cathode and IrO2 or RuO2 for the anode). However, these metals are rare and expensive, and hence lower cost and more abundant catalysts are needed if electrolytically produced hydrogen is to become more widely available. Herein, we show that electrode-film formation from aqueous solutions of first row transition metal ions at pH 1.6 can be induced under the action of an appropriate cell bias and that in the case of cobalt voltages across the cell in excess of 2 V lead to the formation of a pair of catalysts that show functional stability for oxygen evolution and proton reduction for over 24 h. We show that these films are metastable and that if the circuit is opened, they redissolve into the electrolyte bath with concomitant O-2 and H-2 evolution, such that the overall Faradaic efficiency for charge into the system versus amounts of gases obtained approaches unity for both O-2 and H-2. This work highlights the ability of first row transition metals to mediate heterogeneous electrolytic water splitting in acidic media by exploiting, rather than trying to avoid, the natural propensity, of the catalysts to dissolve at the low pHs used. This in turn we hope will encourage others to examine the promise of metastable electrocatalysts based on abundant elements for a range of reactions for which they have traditionally been overlooked on account of their perceived instability under the prevailing conditions.