在碱性条件下，层状氧化锰对无铁/镍电解液中水氧化的反应性低得惊人,Inorganic Chemistry

当前位置： X-MOL 学术 › Inorg. Chem. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

在碱性条件下，层状氧化锰对无铁/镍电解液中水氧化的反应性低得惊人
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2022-01-14 , DOI: 10.1021/acs.inorgchem.1c03665
Mahya Salmanion ₁ , Ivan Kondov ₂ , Matthias Vandichel ₃ , Pavlo Aleshkevych ₄ , Mohammad Mahdi Najafpour _{1,

5,

6}

Affiliation

到目前为止，许多关于 Mn 氧化物的析氧反应 (OER) 的研究都集中在活性上。然而，确定性能最佳的活性位点和相应的催化循环也至关重要。在此，首次研究了层状氧化锰在无铁/镍的 KOH 中对 OER 的真实本征活性。在 pH ≈ 14 时，在无 Fe/Ni KOH 存在下，层状锰氧化物的 OER 开始发生在 1.72 V（与可逆氢电极 (RHE) 相比）。在 Fe 离子存在的情况下，层状氧化锰的 OER 过电位降低了 190 mV，而 Tafel 斜率则显着降低（从 172.8 到 49 mV/十年）。此外，我们发现在层状氧化锰的存在下，Ni 和 Fe 离子都显着增加了 OER，但是，在碱性条件下，纯层状氧化锰在没有 Ni 和 Fe 的情况下并不是 OER 的有效催化剂。因此，纯层状氧化锰和电解质是发现层状氧化锰在 OER 中的真正内在活性的关键因素。我们的结果对碱性条件下层状锰氧化物对 OER 的高效性提出了质疑，并且还阐明了在碱性条件下层状锰氧化物存在时电解液中镍和铁杂质对 OER 的重要作用。总体而言，计算模型支持来自实验结构和电化学表征的结论。特别是，用 Fe 替代掺杂可将热力学 OER 过电位降低至 310 mV。此外，计算出的无铁结构的热力学 OER 起始电位高于 1。

"点击查看英文标题和摘要"

Surprisingly Low Reactivity of Layered Manganese Oxide toward Water Oxidation in Fe/Ni-Free Electrolyte under Alkaline Conditions

So far, many studies on the oxygen-evolution reaction (OER) by Mn oxides have been focused on activity; however, the identification of the best performing active site and corresponding catalytic cycles is also of critical importance. Herein, the real intrinsic activity of layered Mn oxide toward OER in Fe/Ni-free KOH is studied for the first time. At pH ≈ 14, the onset of OER for layered Mn oxide in the presence of Fe/Ni-free KOH happens at 1.72 V (vs reversible hydrogen electrode (RHE)). In the presence of Fe ions, a 190 mV decrease in the overpotential of OER was recorded for layered Mn oxide as well as a significant decrease (from 172.8 to 49 mV/decade) in the Tafel slope. Furthermore, we find that both Ni and Fe ions increase OER remarkably in the presence of layered Mn oxide, but that pure layered Mn oxide is not an efficient catalyst for OER without Ni and Fe under alkaline conditions. Thus, pure layered Mn oxide and electrolytes are critical factors in finding the real intrinsic activity of layered Mn oxide for OER. Our results call into question the high efficiency of layered Mn oxides toward OER under alkaline conditions and also elucidate the significant role of Ni and Fe impurities in the electrolyte in the presence of layered Mn oxide toward OER under alkaline conditions. Overall, a computational model supports the conclusions from the experimental structural and electrochemical characterizations. In particular, substitutional doping with Fe decreases the thermodynamic OER overpotential up to 310 mV. Besides, the thermodynamic OER onset potential calculated for the Fe-free structures is higher than 1.7 V (vs RHE) and, thus, not in the stability range of Mn oxides.

更新日期：2022-01-31

点击分享查看原文

点击收藏

阅读更多本刊最新论文本刊介绍/投稿指南

全部期刊列表>>