Integrating defective nanoparticles (NPs) into a porous one-dimensional (1D) architecture is highly desirable for electrocatalysis due to the enhanced exposure of defective sites and accelerated mass transport features, yet it is a great challenge. Here, we report the synthesis of defective metal oxide NPs interconnected with porous nanofibers via a unique space confined strategy. Central to this strategy is encapsulating Prussian blue analogue (PBA) cubes into polyacrylonitrile (PAN) nanofibers. Due to the distinct pyrolysis behaviors of PBAs and PAN (i.e., expansion outwards, and contraction inwards, respectively), PAN confers a space confined effect on the PBA-derived metal oxides during calcination in air, resulting in the formation of various lattice defects and unsaturated metal sites on the metal oxides. Consequently, with unsaturated metal sites and an advantageous architecture (i.e., 1D porous nanofibers), the resulting nanofibers with P dopants display good performance for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. Notably, as bifunctional electrocatalysts, the nanofibers deliver an overall water-splitting current density of 10 mA cm⁻² at a small voltage of 1.52 V. This work paves new pathways toward utilizing distinct pyrolysis behaviours of metal–organic compounds and polymers to construct defective nanomaterials with advanced architectures.

中文翻译：

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在多孔纳米纤维内构造有缺陷的金属氧化物进行电催化作用的独特空间受限策略

由于缺陷位点的暴露增加和加速的传质特性，将有缺陷的纳米颗粒（NPs）集成到多孔的一维（1D）结构中对于电催化是非常需要的，但这是一个巨大的挑战。在这里，我们报告了通过独特的空间限制策略与多孔纳米纤维互连的有缺陷的金属氧化物NP的合成。该策略的核心是将普鲁士蓝类似物（PBA）立方体封装到聚丙烯腈（PAN）纳米纤维中。由于PBA和PAN具有不同的热解行为（即（分别向外扩展和向内收缩），PAN在空气中煅烧期间对PBA衍生的金属氧化物具有空间限制作用，导致在金属氧化物上形成各种晶格缺陷和不饱和金属位点。因此，具有不饱和金属位点和有利的结构（即，一维多孔纳米纤维），所得的具有P掺杂剂的纳米纤维分别显示出良好的氧析出反应（OER）和氢析出反应（HER）的性能。值得注意的是，作为双功能电催化剂，纳米纤维的总水分解电流密度为10 mA cm ^-2 在1.52 V的小电压下工作。这项工作为利用金属-有机化合物和聚合物的独特热解行为构造具有先进结构的有缺陷的纳米材料铺平了新的途径。