Design and fabrication of cost-effective transition metal and their oxides-based nanocomposites are of paramount significance for metal-air batteries and water-splitting. However, the traditional optimized designs for nanostructure are complicated, low-efficient and underperform for wide-scale applications. Herein, a novel hierarchical framework of hollow Ni/NiFe₂O₄-CNTs composite microsphere forcibly-assembled by zero-dimensional (0D) Ni/NiFe₂O₄ nanoparticle (< 16 nm) and one-dimensional (1D) self-supporting CNTs was fabricated successfully. Benefitted from the unique nanostructure, such monohybrids can achieve remarkable oxygen evolution reaction (OER) performance in alkaline media with a low overpotential and superior durability, which exceeds most of the commercial catalysts based on IrO₂/RuO₂ or other non-noble metal nanomaterials. The enhanced OER performance of Ni/NiFe₂O₄-CNTs composite is mainly ascribed to the increased catalytic activity and the optimized conductivity induced by the effects of strong hierarchical coupling and charge transfers between CNTs and Ni/NiFe₂O₄ nanoparticles. These effects are greatly boosted by the polarized heterojunction interfaces confirmed by electron holography. The density functional theory (DFT) calculation indicates the epitaxial Ni further enriches the intrinsic electrons contents of NiFe₂O₄ and thus accelerates absorption/desorption kinetics of OER intermediates. This work hereby paves a facile route to construct the hollow composite microsphere with excellent OER electrocatalytic activity based on non-noble metal oxide/CNTs.

中文翻译：

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中空Ni / NiFe 2 O 4 -CNTs微球通过喷雾干燥的分层耦合效应，以增强析氧电催化作用

具有成本效益的过渡金属及其基于氧化物的纳米复合材料的设计和制造对于金属-空气电池和水分解而言至关重要。但是，传统的纳米结构优化设计复杂，效率低且在大规模应用中表现不佳。本文以零维（0D）Ni / NiFe ₂ O ₄强制组装的空心Ni / NiFe ₂ O ₄ -CNTs复合微球的新型分层框架。成功地制备了纳米粒子（<16 nm）和一维（1D）自支撑碳纳米管。得益于独特的纳米结构，此类单杂化物可以在碱性介质中实现出色的氧释放反应（OER）性能，并且具有低过电势和卓越的耐久性，这超出了大多数基于IrO ₂ / RuO ₂或其他非贵金属纳米材料的商业催化剂。Ni / NiFe ₂ O ₄ -CNTs复合材料的OER性能增强主要归因于CNT与Ni / NiFe ₂ O ₄之间强的层级耦合和电荷转移的影响，从而提高了催化活性和优化了电导率。纳米粒子。电子全息图证实的极化异质结界面大大增强了这些效应。密度泛函理论（DFT）计算表明，外延Ni进一步丰富了NiFe ₂ O ₄的本征电子含量，从而加速了OER中间体的吸收/解吸动力学。因此，这项工作为基于非贵金属氧化物/ CNTs构建具有优异的OER电催化活性的中空复合微球铺平了一条容易的路线。