Searching for cost‐effective and high‐performance electrocatalysts for hydrogen production is of paramount importance. Herein, nickel‐copper (NiCu) alloy nanoparticles are encapsulated into graphitic shells via an ambient‐pressure chemical vapor deposition process. The resulting carbon‐encapsulated NiCu (denoted as NiCu@C) composite possesses a well‐defined core–shell structure with tunable thicknesses of the shells and is examined as electrocatalysts for the hydrogen evolution reaction (HER) in acidic, neutral, and alkaline solutions. Electrochemical measurements indicate that the activity of the NiCu@C highly depends on the thickness of the shell. Single‐layered graphene encapsulated NiCu nanoparticles show remarkable HER activity and durability. To obtain a current density of 10 mA cm⁻², overpotentials of 48, 164, and 74 mV are needed in electrolyte solutions with pH = 0, 7, and 14, respectively. Such low overpotentials render the composite as one of the most active nonprecious electrocatalysts. Accelerated durability tests demonstrate that the NiCu@C catalysts exhibit excellent stability. Density function theory calculations are conducted to investigate the electronic structures of the NiCu@C. It is found that the representative Ni₄₃Cu₁₂@C₂₄₀ model shows an ideal adsorption energy of hydrogen (−0.03 eV), manifesting its high HER activity.

中文翻译：

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镍-铜合金包裹在石墨碳壳中作为氢析出反应的电催化剂

寻找生产氢气的具有成本效益的高性能电催化剂至关重要。此处，镍铜（NiCu）合金纳米粒子通过常压化学气相沉积工艺封装在石墨壳中。所得的碳包封的NiCu（表示为NiCu @ C）复合材料具有定义明确的核-壳结构，壳的厚度可调节，并且已在酸性，中性和碱性溶液中用作制氢反应（HER）的电催化剂。 。电化学测量表明，NiCu @ C的活性高度取决于壳的厚度。单层石墨烯包封的NiCu纳米颗粒具有出色的HER活性和耐久性。获得10 mA cm ^-2的电流密度在pH = 0、7和14的电解质溶液中，分别需要48、164和74 mV的过电势。如此低的超电势使复合材料成为最活跃的非贵金属电催化剂之一。加速的耐久性试验表明，NiCu @ C催化剂具有出色的稳定性。进行密度函数理论计算以研究NiCu @ C的电子结构。发现具有代表性的Ni ₄₃ Cu ₁₂ @C ₂₄₀模型显示出理想的氢吸附能量（-0.03 eV），表现出较高的HER活性。