Developing inexpensive and efficient electrocatalysts for hydrogen evolution reaction (HER) during alkaline water electrolysis is crucial for renewable and sustainable energy harvesting. Herein, we report a novel hybrid electrocatalyst comprising atomically dispersed Ni–N_x species anchored porous carbon (Ni–N–C) matrix with embedded Ni nanoparticles for HER. This new catalyst is synthesized via pyrolysis of hydrothermally prepared supermolecular composite of dicyandiamide and Ni ions followed by an acid etching treatment. The achieved hybrid exhibits superior catalytic performance toward HER with a small overpotential of 147 mV at 10 mA cm⁻² and a low Tafel slope of 114 mV dec⁻¹, comparable to those of state-of-the-art heteroatom-doped nanocarbon catalysts and even outperforming other reported transition-metal-based compounds in basic media. Experimental observations and theoretical calculations reveal that the presence of Ni nanoparticles can optimize surface states of Ni−N_x active centers and reduce energy barriers of dissociated water molecules, which synergistically improve OH⁻ adsorption and promote HER kinetics. When served as electrodes for both cathode and anode, an alkaline water electrolyzer could afford a current density of 10 mA cm⁻² at a low cell voltage of 1.58 V, rivalling the sufficiently high overpotentials of integrated Pt/C–Ir/C benchmark electrodes.

中文翻译：

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通过加速水离解动力学， 在原子分散的Ni–N _x种具有嵌入的Ni纳米颗粒的锚固多孔碳上有效地释放出碱氢†

开发廉价，有效的碱性水电解过程中用于氢释放反应（HER）的电催化剂对于可再生和可持续的能源收集至关重要。在本文中，我们报道了一种新型的混合电催化剂，该催化剂包括原子分散的Ni–N _x物种锚固的多孔碳（Ni–N–C）基质以及用于HER的嵌入式Ni纳米颗粒。这种新催化剂是通过热解双氰胺和Ni离子的水热制备超分子复合物，然后进行酸蚀刻处理而合成的。所获得的杂化物表现出优异的针对HER的催化性能，在10 mA cm ^-2时具有147 mV的小过电位和114 mV dec ^-1的低Tafel斜率与最先进的杂原子掺杂纳米碳催化剂相比，甚至在基本介质中的表现优于其他已报道的过渡金属基化合物。实验观察和理论计算表明，镍纳米颗粒的存在可以优化的Ni-N表面状态_X活性中心和降低解离水分子，它们协同提高OH的能量势垒^-吸附和促进HER动力学。当用作阴极和阳极的电极时，碱性水电解槽在1.58 V的低电池电压下可提供10 mA cm ^-2的电流密度，可与集成的Pt / C–Ir / C基准电极的足够高的超电势相媲美。 。