Engineering Facets and Oxygen Vacancies over Hematite Single Crystal for Intensified Electrocatalytic H2O2 Production,Advanced Functional Materials

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Engineering Facets and Oxygen Vacancies over Hematite Single Crystal for Intensified Electrocatalytic H2O2 Production
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2020-04-27 , DOI: 10.1002/adfm.201910539
Ruijie Gao _{1,

2} , Lun Pan _{1,

2} , Zhengwen Li ₁ , Chengxiang Shi _{1,

2} , Yunduo Yao _{1,

2} , Xiangwen Zhang _{1,

2} , Ji‐Jun Zou _{1,

2}

Affiliation

Hydrogen peroxide is a highly valuable chemical, and electrocatalytic oxygen reduction towards H₂O₂ offers an alternative method for safe on‐site applications. Generally, low‐cost hematite (α‐Fe₂O₃) is not recognized as an efficient electrocatalyst because of its inert nature, but it is herein reported that α‐Fe₂O₃ can be endowed with high catalytic activity and selectivity via the engineering of facets and oxygen vacancies. Density‐functional theory (DFT)calculations predict that the {001} facet is intrinsically selective for H₂O₂ production, and that oxygen vacancies can trigger the high activity, providing sites for O₂ adsorption and protonation, stabilizing the *OOH intermediate, and preventing cleavage of the OO bond. The synthesized oxygen‐defective α‐Fe₂O₃ single crystals with exposed {001} facets achieve high selectivities for H₂O₂ of >90%, >88%, and >95% in weakly acidic, neutral, and alkaline electrolytes, respectively, and the H₂O₂ production rate reaches 454 mmol g⁻¹_cat h⁻¹ at 0.1 V versus RHE under alkaline conditions. In an anion exchange membrane fuel cell, a maximum H₂O₂ production of 546.8 mmol L⁻¹ with a high Faradaic efficiency of 80.5% is achieved. Thus, this work details a low‐cost catalyst feasible for H₂O₂ synthesis, and highlights the feasibility of theoretical catalyst design for practical applications.

中文翻译：

赤铁矿单晶上增强电催化生成H2O2的工程学方面和氧空位

过氧化氢是一种非常有价值的化学物质，向H ₂ O _2的电催化氧还原是安全现场应用的另一种方法。一般，低成本的赤铁矿（α-的Fe ₂ ö ₃）不被识别为由于其惰性性质的有效电催化剂，但是在本文中报道了的α-Fe ₂ ö ₃能够经由高的催化活性和选择性被赋予刻面和氧空位的工程。密度泛函理论（DFT）的计算表明，{001}晶面对H ₂ O _2的产生具有内在选择性，并且氧空位可以触发高活性，从而为O提供了位点₂吸附和质子化，稳定* OOH中间体，并防止OO键断裂。将合成的氧缺陷的α-Fe _2个ö ₃单晶与露出{001}面实现为H高选择性₂ ö ₂ > 90％，> 88％，> 95％在弱酸性，中性和碱性电解质，在碱性条件下，相对于RHE，在0.1 V下H ₂ O _2的生产率达到了454 mmol g ^-1_cat h ^-1。在阴离子交换膜燃料电池中，最大H ₂ O ₂产生为546.8 mmol L ^-1法拉第效率高达80.5％。因此，这项工作详述了可用于H ₂ O ₂合成的低成本催化剂，并强调了理论催化剂设计在实际应用中的可行性。

更新日期：2020-04-27

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