NaBH(4) induces a high ratio of Ni(3+)/Ni(2+) boosting OER activity of the NiFe LDH electrocatalyst.
NaBH(4) induces a high ratio of Ni(3+)/Ni(2+) boosting OER activity of the NiFe LDH electrocatalyst.
复制标题
NaBH4 诱导高比例的 Ni3/Ni2 提高 NiFe LDH 电催化剂的 OER 活性
作者：
电化学水裂解是一种很有前途的制氢方法，但缓慢的析氧反应动力学（OER）极大地限制了水裂解的整体转化效率。过渡金属类水滑石（TMDHs）是一种高效的非贵金属OER催化剂，特别是Ni-Fe类水滑石（NiFeLDHs），受到了广泛的关注。具有大配位数的高价Ni 3+物种在OER催化中起着至关重要的作用。在本文中，我们报告了一个令人惊讶的发现，NiFe LDH和NaBH 4与多金属离子之间的反应诱导了Fe 3+周围的空位形成和Ni 3+的富集，关键地激活了OER性能。发现Ni 3 +/Ni 2+的比率与OER性能密切相关，很好地解释了Ni 3+离子在电催化中的八面体位点中的主导作用。值得注意的是，直接在泡沫镍（NF）上的NaBH 4处理的NiFe LDH（表示为NaBH 4-NiFe LDH@NF）表现出出色的OER性能，在100 mA cm−2下的过电位仅为310 mV，塔菲尔斜率为47 mV dec−1。对于我们研究的一系列具有不同金属组合的TM LDH，发现高价金属离子与OER性能正相关。
Electrochemical water splitting is a promising way to produce hydrogen gas, but the sluggish kinetics of the oxygen evolution reaction (OER) extremely restrict the overall conversion efficiency of water splitting. Transition metal based LDHs (TM LDHs) are one of the most effective non-noble metal OER catalysts and have attracted wide interest, especially the nickel–iron LDH (NiFe LDH). The high valence Ni3+ species with a large coordination number play a vital role in OER catalysis. Herein, we report on a surprising discovery that reaction between NiFe LDH and NaBH4 with multi-hydrides induces vacancy formation around Fe3+ and enrichment in Ni3+, crucially activating the OER performance. The ratio of Ni3+/Ni2+ is found to be closely tied to the OER performance, nicely accounting for the leading role of Ni3+ ions in octahedral sites in electrocatalysis. Significantly, the NaBH4 treated NiFe LDH directly on nickel foam (NF), denoted as NaBH4–NiFe LDH@NF exhibited an outstanding OER performance with an overpotential of only 310 mV at 100 mA cm−2, and a Tafel slope of 47 mV dec−1. For the series of TM LDHs we studied with different metal combinations, the high valence metal ion is found to be positively related to OER performance.
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