The construction of NiFe-based composites on foam metal is an advanced strategy to design high-performance catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, we chose Fe foam (FF) as the substrate, which was first modified by anodic electrodeposition to form a porous and loose FeS_x/FeO_x layer. This modified layer facilitates the construction of nanoflower-structured NiFeS₂/NiFe₂O₄ composites with large electrochemical active surface area, higher Ni content and enhanced ratio of Ni³⁺ to Ni²⁺, compared with the sample fabricated by direct etching FF. The prepared NiFeS₂/NiFe₂O₄/FF electrode only requires overpotentials of 242 and 273 mV to achieve current densities of 100 and 500 mA cm⁻² for OER, respectively. It also possesses faster reaction kinetics with a low Tafel slope of 31.12 mV dec^-1 and superior durability without potential reduction for 200 h at a large current density of 500 mA cm⁻². Meanwhile, the performance of overall water splitting cell assembled with NiFeS₂/NiFe₂O₄/FF is better than that of cell based on the noble metal Pt/C/FF||RuO₂/FF. This work provides a simple and cost-effective strategy for constructing efficient electrocatalysts, making it promising for large-scale industrial applications in alkaline water electrolysis.

中文翻译：

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通过蚀刻改性泡沫铁构建 NiFeS2/NiFe2O4 复合材料作为整体分解水的高效双功能催化剂


在泡沫金属上构建 NiFe 基复合材料是设计用于析氢反应 （HER） 和析氧反应 （OER） 的高性能催化剂的先进策略。在此，我们选择泡沫铁 （FF） 作为基材，首先通过阳极电沉积对其进行改性，形成多孔松散的 FeS_x/FeO_x 层。与直接刻蚀 FF 制备的样品相比，该改性层有助于构建纳米花结构的 NiFeS₂/NiFe₂O₄ 复合材料，与直接蚀刻 FF 制备的样品相比，具有较大的电化学活性表面积、更高的 Ni 含量和增强的 Ni³⁺ 与 Ni²⁺ 的比率。所制备的 NiFeS₂/NiFe₂O₄/FF 电极只需要 242 和 273mV 的过电位，即可分别实现 100 和 500mAcm⁻² 的 OER 电流密度。它还具有更快的反应动力学，具有 31.12mV ^dec-1 的低塔菲尔斜率，并且在 500mAcm⁻² 的大电流密度下 200 小时内无电位还原。同时，以 NiFeS₂/NiFe₂O₄/FF 组装的分解水电池的整体性能优于基于贵金属 Pt/C/FF||RuO₂/FF 的。这项工作为构建高效的电催化剂提供了一种简单且具有成本效益的策略，使其有望在碱性水电解中的大规模工业应用中发挥作用。