<br>海水电解中镍铁基阳极微区酸化驱动的降解机制,ACS Applied Materials & Interfaces

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海水电解中镍铁基阳极微区酸化驱动的降解机制
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2024-01-14 , DOI: 10.1021/acsami.3c13929
Mengyi Tang _{1,

2} , Kaifa Du _{1,

2} , Rui Yu _{1,

2} , Hao Shi _{1,

2} , Peilin Wang _{1,

2} , Yifan Guo _{1,

2} , Qinyi Wei _{1,

2} , Huayi Yin _{1,

2} , Dihua Wang _{1,

2}

Affiliation

阳极稳定性对于高效可靠的海水电解槽至关重要。本文通过阳极氧化制备了 NiFe 基薄膜催化剂作为模型电极，在模拟碱性海水（1 M KOH + 0.5 M NaCl）中表现出令人满意的析氧性能，在 100 mA cm 下过电势为 348 mV ^–2且长期稳定性超过 100 小时。之后，评估了电解液的电流密度和本体pH值对其稳定性的影响。研究发现，电极稳定性对电解条件敏感，在 0.1 M KOH + 0.5 M NaCl 中，电极稳定性在 20 mA cm ^–2时失败，但在 0.5 M KOH + 0.5 M NaCl 中，电极稳定性超过 500 mA cm ^–2 。电极溶解，电解过程中在非常接近电极表面的区域立即形成一些沉淀物。这可以归因于阳极极化下电极/电解质界面与本体电解质之间的 pH 差异。也就是说，微区酸化加速了^Cl-对电极的腐蚀，从而影响了电极的稳定性。对不同电解条件下电极的运行性能进行分类，以进一步分析其降解行为，产生分别对应于稳定析氧、剧烈溶解-沉淀和完全钝化过程的三个区域。因此，增加整体pH值可以减轻微区酸化并提高阳极在高电流密度下的稳定性。总的来说，这项研究为理解 NiFe 基催化剂的降解机制提供了新的见解，并为阳极的应用提供了电解质工程策略。

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Microzone-Acidification-Driven Degradation Mechanism of the NiFe-Based Anode in Seawater Electrolysis

The anode stability is critical for efficient and reliable seawater electrolyzers. Herein, a NiFe-based film catalyst was prepared by anodic oxidation to serve as a model electrode, which exhibited a satisfactory oxygen evolution performance in simulated alkaline seawater (1 M KOH + 0.5 M NaCl) with an overpotential of 348 mV at 100 mA cm^–2 and a long-term stability of over 100 h. After that, the effects of the current density and bulk pH of the electrolyte on its stability were evaluated. It was found that the electrode stability was sensitive to electrolysis conditions, failing at 20 mA cm^–2 in 0.1 M KOH + 0.5 M NaCl but over 500 mA cm^–2 in 0.5 M KOH + 0.5 M NaCl. The electrode dissolved, and some precipitates immediately formed at the region very close to the electrode surface during the electrolysis. This can be ascribed to the pH difference between the electrode/electrolyte interface and the bulk electrolyte under anodic polarization. In other words, the microzone acidification accelerates the corrosion of the electrode by Cl^–, thus affecting the electrode stability. The operational performances of the electrode under different electrolysis conditions were classified to further analyze the degradation behavior, which resulted in three regions corresponding to the stable oxygen evolution, violent dissolution–precipitation, and complete passivation processes, respectively. Thereby increasing the bulk pH could alleviate the microzone acidification and improve the stability of the anode at high current densities. Overall, this study provides new insights into understanding the degradation mechanism of NiFe-based catalysts and offers electrolyte engineering strategies for the application of anodes.

更新日期：2024-01-14

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