Wijten Jochem H J, Garcia-Torregrosa Iván, Dijkman Eva A, Weckhuysen Bert M
Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Research, Universiteitsweg 99, Utrecht, The Netherlands.
Chemphyschem. 2020 Mar 17;21(6):518-524. doi: 10.1002/cphc.201901219. Epub 2020 Feb 11.
Non-noble metal electro-catalysts for water splitting are highly desired when we are moving towards a society where green electrons are becoming abundantly available, offering clear prospects to make our society more sustainable. In this work, Ni-Fe-S is reported as a high performing anode material for the water splitting reaction, operating at low overpotentials and showing high apparent stability. Furthermore, Ni-Mo electrodes are developed on metallic foam substrates and optimized in terms of their performance. The Ni-Fe-S material as anode, combined and integrated with Ni-Mo as cathode in a cell configuration, splits water at 10 mA cm and a potential of 1.55 V. Similar to previous reports, we confirm that Mo leaches from Ni-Mo/Ni foam electrodes. Cycling tests and ICP-AES measurements show that the stability of Ni-Fe-S is apparent, and that in reality S is leaching from the material as was already suggested in literature. We expand on this knowledge and show that the leaching of S is dependent on both pH and the cation used during electrocatalysis. Furthermore, we find that applying an oxidative potential is in truth stabilizing towards S and that the alkalinity causes leaching. S was furthermore mobile and found to segregate towards the surface. Finally, using too low pH values (11 and lower) result in the passivating hydroxide metal layers being destroyed and the Ni-Fe-S dissolving completely.
当我们迈向一个绿色电子变得丰富可得的社会，这为使我们的社会更具可持续性提供了清晰前景时，用于水分解的非贵金属电催化剂备受期待。在这项工作中，Ni-Fe-S被报道为一种用于水分解反应的高性能阳极材料，在低过电位下运行并表现出高表观稳定性。此外，在金属泡沫基板上开发了Ni-Mo电极，并对其性能进行了优化。在电池配置中，将Ni-Fe-S材料作为阳极与Ni-Mo作为阴极组合并集成，在10 mA cm⁻²的电流密度和1.55 V的电位下实现水分解。与之前的报道类似，我们证实Mo从Ni-Mo/泡沫镍电极中浸出。循环测试和ICP-AES测量表明，Ni-Fe-S的稳定性是表观的，实际上正如文献中已经指出的那样，S正从材料中浸出。我们进一步拓展了这一认识，并表明S的浸出取决于pH值和电催化过程中使用的阳离子。此外，我们发现施加氧化电位实际上对S具有稳定作用，而碱度会导致浸出。S还具有移动性，并发现其向表面偏析。最后，使用过低的pH值（11及更低）会导致钝化的氢氧化物金属层被破坏，Ni-Fe-S完全溶解。
