The development of cost-effective bifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is critical to realize the commercialization of electrocatalytic water splitting. Herein, an effective defect engineering strategy, Ar plasma treatment, was adopted to promote both the HER and OER activity of pre-synthesized Fe-doped Ni₃S₂ nano-pyramid arrays on nickel foam. The abundant sulfur vacancies endow the Fe-doped Ni₃S₂ nano-pyramid arrays with a low overpotential of 171 mV at 10 mA cm⁻² and a small Tafel slope of 49 mV dec⁻¹ to drive the OER in 1.0 M KOH. Density functional theory (DFT) calculations reveal that sulfur vacancies together with Fe doping can effectively regulate the electronic structure of Ni₃S₂, resulting in increased electrical conductivity and a reduced energy barrier, as well as enhanced reaction kinetics through weakening the binding strength between active sites and intermediates. Such defect-rich hetero-metal doped catalyst also delivers enhanced HER activity. As a result, a cell assembled using defect-rich Fe-Ni₃S₂ nano-pyramid arrays as both the anode and cathode needs a low applied voltage of 1.63 V to reach a current density of 10 mA cm⁻², and exhibits outstanding long-term stability up to 60 h.

中文翻译：

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硫空位促进了Fe掺杂的Ni3S2纳米金字塔阵列作为整体水分解的有效双功能电催化剂

开发用于氢气释放反应（HER）和氧气释放反应（OER）的具有成本效益的双功能催化剂对于实现电催化水分解的商业化至关重要。在本文中，采用有效的缺陷工程策略，即Ar等离子体处理，以促进镍泡沫上预合成的Fe掺杂的Ni ₃ S ₂纳米金字塔阵列的HER和OER活性。大量的硫空位赋予了Fe掺杂的Ni ₃ S ₂纳米金字塔阵列在10 mA cm ^-2时的低电势为171 mV，而塔菲尔斜率较小，为49 mV dec ^-1在1.0 M KOH中驱动OER。密度泛函理论（DFT）计算表明，硫空位与Fe掺杂一起可以有效调节Ni ₃ S ₂的电子结构，从而提高电导率和降低能垒，并通过削弱两者之间的结合强度来增强反应动力学。活性部位和中间体。这种富含缺陷的杂金属掺杂的催化剂还提供增强的HER活性。结果，使用富含缺陷的Fe-Ni ₃ S ₂纳米金字塔阵列作为阳极和阴极组装的电池需要1.63 V的低施加电压以达到10 mA cm ^-2的电流密度，并表现出出色的性能。长期稳定性长达60小时。