Fe-doped mayenite electride composite with 2D reduced Graphene Oxide: As a non-platinum based, highly durable electrocatalyst for Oxygen Reduction Reaction.,Scientific Reports

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Fe-doped mayenite electride composite with 2D reduced Graphene Oxide: As a non-platinum based, highly durable electrocatalyst for Oxygen Reduction Reaction.
Scientific Reports ( IF 3.8 ) Pub Date : 2019-12-24 , DOI: 10.1038/s41598-019-55207-6
Karim Khan _{1,

2,

3} , Ayesha Khan Tareen ₂ , Muhammad Aslam ₄ , Sayed Ali Khan ₅ , Qasim Khan ₅ , Qudrat Ullah Khan ₅ , Muhammad Saeed ₆ , Awais Siddique Saleemi ₇ , Maryam Kiani ₅ , Zhengbiao Ouyang ₃ , Han Zhang ₂ , Zhongyi Guo ₁

Affiliation

Since the last decades, non-precious metal catalysts (NPMC), especially iron based electrocatalysts show sufficient activity, potentially applicant in oxygen reduction reaction (ORR), however they only withstand considerable current densities at low operating potentials. On the other hand iron based electrocatalysts are not stable at elevated cathode potentials, which is essential for high energy competence, and its remains difficult to deal. Therefore, via this research a simple approach is demonstrated that allows synthesis of nanosize Fe-doped mayenite electride, [Ca24Al28O64]4+·(e-)4 (can also write as, C12A7-xFex:e-, where doping level, x = 1) (thereafter, Fe-doped C12A7:e-), consist of abundantly available elements with gram level powder material production, based on simple citrate sol-gel method. The maximum achieved conductivity of this first time synthesized Fe-doped C12A7:e- composite materials was 249 S/cm. Consequently, Fe-doped C12A7:e- composite is cost-effective, more active and highly durable precious-metal free electrocatalyst, with 1.03 V onset potential, 0.89 V (RHE) half-wave potential, and ~5.9 mA/cm2 current density, which is higher than benchmark 20% Pt/C (5.65 mA/cm2, and 0.84 V). The Fe-doped C12A7:e- has also higher selectivity for desired 4e- pathway, and more stable than 20 wt% Pt/C electrode with higher immunity towards methanol poisoning. Fe-doped C12A7:e- loses was almost zero of its original activity after passing 11 h compared to the absence of methanol case, indicates that to introduce methanol has almost negligible consequence for ORR performance, which makes it highly desirable, precious-metal free electrocatalyst in ORR. This is primarily described due to coexistence of Fe-doped C12A7:e- related active sites with reduced graphene oxide (rGO) with pyridinic-nitrogen, and their strong coupling consequence along their porous morphology textures. These textures assist rapid diffusion of molecules to catalyst active sites quickly. In real system maximum power densities reached to 243 and 275 mW/cm2 for Pt/C and Fe-doped C12A7:e- composite, respectively.

中文翻译：

Fe 掺杂钙铝石电子化合物与二维还原氧化石墨烯复合材料：作为一种非铂基、高度耐用的氧还原反应电催化剂。

近几十年来，非贵金属催化剂（NPMC），特别是铁基电催化剂表现出足够的活性，有望应用于氧还原反应（ORR），但它们只能在低工作电位下承受相当大的电流密度。另一方面，铁基电催化剂在升高的阴极电势下不稳定，而阴极电势对于高能量能力至关重要，并且仍然难以处理。因此，通过这项研究，证明了一种简单的方法，可以合成纳米尺寸的铁掺杂钙铝石电子化合物，[Ca24Al28O64]4+·(e-)4（也可以写为，C12A7-xFex:e-，其中掺杂水平，x = 1)（此后为铁掺杂C12A7:e-），由丰富的可用元素组成，基于简单的柠檬酸盐溶胶-凝胶方法，可进行克级粉末材料生产。首次合成的Fe掺杂C12A7:e-复合材料的最大电导率为249 S/cm。因此，Fe 掺杂的 C12A7:e- 复合材料是一种经济高效、活性更高且高度耐用的不含贵金属的电催化剂，具有 1.03 V 的起始电位、0.89 V (RHE) 半波电位和 ~5.9 mA/cm2 电流密度，高于基准 20% Pt/C（5.65 mA/cm2 和 0.84 V）。Fe 掺杂的 C12A7:e- 对所需的 4e- 途径也具有更高的选择性，并且比 20 wt% Pt/C 电极更稳定，对甲醇中毒具有更高的免疫力。与不存在甲醇的情况相比，Fe 掺杂的 C12A7:e- 在经过 11 小时后其原始活性损失几乎为零，表明引入甲醇对 ORR 性能的影响几乎可以忽略不计，这使得它非常理想，不含贵金属ORR 中的电催化剂。这主要是由于 Fe 掺杂的 C12A7:e 相关活性位点与还原氧化石墨烯 (rGO) 与吡啶氮的共存，以及它们沿着多孔形态纹理的强耦合结果。这些纹理有助于分子快速扩散到催化剂活性位点。在实际系统中，Pt/C 和 Fe 掺杂的 C12A7:e- 复合材料的最大功率密度分别达到 243 和 275 mW/cm2。

更新日期：2019-12-25

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