Electrochemical stability of stainless-steel-made anode for alkaline water electrolysis: Surface catalyst nanostructures and oxygen evolution overpotentials under applying potential cycle loading
Electrochemical stability of stainless-steel-made anode for alkaline water electrolysis: Surface catalyst nanostructures and oxygen evolution overpotentials under applying potential cycle loading
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DOI：
10.1016/j.elecom.2020.106902
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发表时间：
2020-12
影响因子：
5.4
通讯作者：
Naoto Todoroki;T. Wadayama
中科院分区：
文献类型：
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作者：
Naoto Todoroki;T. Wadayama
研究了碱性水电解用NiFe-氢氧化物/氧化物催化层不锈钢(SS)阳极(NiFe-HyOx/SS)的电化学稳定性。在75℃的316SS板上，30 mA/cm2的1 mM KOH溶液中恒流密度电解5 h，得到NiFe-HyOx催化层，当电流密度为100 mA/cm2时，析氧反应的初始过电势约为270 mV，而在20℃时，在7 mM KOH中分别施加0.5和1.8 nV的20,000次电位循环(PS)时，析氧反应的初始过电势几乎保持不变。PCS负载前后的扫描电子显微镜观察表明，50 nm厚的纳米纤维状NiFe-HyOx催化层的结构和厚度保持不变，而催化层下方形成了约850 nm厚的相对致密的NiFe-(HyOx)氧化物中间层。结果表明，NiFe-HyOx/SS阳极优异的OER性能来源于表面催化层。
We investigated electrochemical stability of the NiFe-hydroxide/oxide-catalyst-layer covered stainless-steel(SS)-anode (NiFe-HyOx/SS) for alkaline water electrolysis. The NiFe-HyOx catalyst layer was synthesized through constant current density electrolysis of 30 mA/cm2in 1 M KOH solution of a 316 SS plate at 75 ℃ for 5 h. The initial overpotential of oxygen evolution reaction (OER) was estimated to be ca. 270 mV at 100 mA/cm2and the potential kept almost constant during applying the 20,000 potential cycles (PCs) of 0.5 and 1.8 V vs. reversible hydrogen electrode in 7 M KOH at 20 ℃. Scanning transmission electron microscopic observations conducted before and after the PCs loading revealed that the 50 nm-thick, nanofiber-like NiFe-HyOx catalyst layer remained unchanged in structure and in thickness, while the ca. 850 nm-thick, relatively dense NiFe-(hydro)oxide interlayer was generated under the catalyst layer. The results suggest that the superior OER property of the NiFe-HyOx/SS anode is originated from the surface catalyst layer.