Surface amorphized nickel hydroxy sulphide for efficient hydrogen evolution reaction in alkaline medium
Surface amorphized nickel hydroxy sulphide for efficient hydrogen evolution reaction in alkaline medium
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DOI：
10.1016/j.cej.2020.127275
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发表时间：
2021-01-15
影响因子：
15.1
通讯作者：
Noda, Suguru
中科院分区：
文献类型：
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作者：
Anantharaj, Sengeni;Sugime, Hisashi;Noda, Suguru
非氧化物/氢氧化物析氢反应（HER）催化剂在暴露于碱时甚至在还原条件下也经历显著程度的羟基化。这种羟基化在碱性HER电催化中的实际作用先前没有给出任何意义。在这项研究中，我们报告了一个有趣的发现，硫化镍一个众所周知的HER电催化剂，当受到阳极电位循环覆盖Ni 2+和Ni 3+氧化还原对导致加速羟基化伴随表面非晶化。结果，实现了改善的电化学表面、更好的HER动力学和更好的电荷转移，在100 mA cm（2）下使HER过电位降低110 mV。这种表面非晶化和羟基化的硫化镍在50 h以上的恒电流和恒电位电解中都表现出优异的稳定性。此外，它还显示出较低的Tafel斜率（120 mV dec（-1））、就2C（dl）而言较高的相对ECSA（3.85 μ F cm（-2））和Ni位点较高的电化学可及性（3.7 × 10（17）cm（-2）），这进一步证明了我们改进非氧化物/氢氧化物催化剂的HER活性的方法的优越性。因此，这项研究开辟了新的途径，重新审视其他非氧化物/氢氧化物催化剂在碱性HER有利于能源和成本效益的氢气产生。
Non-oxide/hydroxide hydrogen evolution reaction (HER) catalysts undergo hydroxylation to a significant extent even under reductive condition when exposed to alkali. Actual role of such hydroxylation in alkaline HER electrocatalysis is not previously given any significance. In this study, we report an intriguing finding that nickel sulfide a well-known HER electrocatalyst when subjected to anodic potential cycling covering Ni2+ and Ni3+ redox couple led to accelerated hydroxylation accompanying surface amorphization. As a result, improved electrochemical surface, better HER kinetics, and better charge transfer were achieved that lowering the HER over potential by 110 mV at 100 mA cm(2). This surface amorphized and hydroxylated nickel sulfide exhibited excellent stability upon both galvanostatic and potentiostatic electrolysis for over 50 h. Besides, it also showed a lower Tafel slope (120 mV dec(-1)), higher relative ECSA in terms of 2C(dl) (3.85 mu F cm(-2)), and higher electrochemical accessibility for Ni sites (3.7 x 10(17) cm(-2)) which further advocate the superiority of our way of improving HER activity of a non-oxide/hydroxide catalyst. Thus, this study open up new avenues for re-examining other nonoxide/hydroxide catalysts in alkaline HER for benefiting the energy and cost-efficient hydrogen generation.