The development of highly efficient noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER) is still a challenge nowadays. In this work, we prepared a highly active electrocatalyst containing phosphorus-doped NiCo₂S₄ nanocrystals grown on carbon nanotube embedded carbon nanofibers (P-NiCo₂S₄@CNT/CNF). The CNTs are involved in enhancing the electrical conductivity of the three-dimensional CNF network through a facile co-electrospinning method, which can facilitate electron transfer to the attached HER active material. Templated by this nanofiber network, the electroactive NiCo₂S₄ is confined to grow perpendicularly onto the CNT/CNF template via a hydrothermal reaction, thus exposing more catalytic active sites. Doping of P into the hybrid via a phosphidation reaction improves the electronic structure of the electroactive NiCo₂S₄, thus decreasing the energy barrier during the HER process. Owing to the synergistic effects from electrical enhancement and the nanostructured morphology, along with P-doping-induced optimization of the electronic structure, the P-NiCo₂S₄@CNT/CNF hybrid exhibits excellent HER performance, with an ultra-low onset overpotential (η) of 27 mV, a remarkable current density of 10 mA cm⁻² at η as low as 74 mV, an impressive exchange current density of 0.79 mA cm⁻² and excellent long-term durability. Furthermore, its electroactivity exceeds that of most reported noble-metal-free electrocatalysts and is comparable to that of Pt, suggesting its great potential as a highly efficient HER catalyst.

中文翻译：

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在电 纺碳纳米纤维上生长的掺磷NiCo ₂ S ₄纳米晶体，是氢释放反应的超高效电催化剂†

如今，开发用于氢气释放反应（HER）的高效无贵金属电催化剂仍然是一项挑战。在这项工作中，我们制备了一种高活性电催化剂，该催化剂包含在碳纳米管内嵌的碳纳米纤维（P-NiCo ₂ S ₄ @ CNT / CNF）上生长的掺磷的NiCo ₂ S ₄纳米晶体。CNT通过简便的共电纺丝法参与增强三维CNF网络的电导率，该方法可以促进电子转移到附着的HER活性材料上。通过该纳米纤维网络进行模板化，电活性NiCo ₂ S ₄被限制为通过以下方式垂直生长在CNT / CNF模板上水热反应，从而暴露出更多的催化活性位。通过磷化反应将P掺杂到杂化物中可改善电活性NiCo ₂ S ₄的电子结构，从而降低HER过程中的能垒。由于电增强和纳米结构形态的协同作用，以及P掺杂引起的电子结构的优化，P-NiCo ₂ S ₄ @ CNT / CNF杂化物表现出优异的HER性能，并且超低的起始过电势（η）为27 mV，在η处的电流密度为10 mA cm ^-2低至74 mV，令人印象深刻的0.79 mA cm ^-2交换电流密度和出色的长期耐用性。此外，其电活性超过了大多数报道的无贵金属电催化剂的电活性，可与Pt相媲美，表明其作为高效HER催化剂的巨大潜力。