State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023 (China).
Angew Chem Int Ed Engl. 2015 Feb 9;54(7):2100-4. doi: 10.1002/anie.201409524. Epub 2015 Jan 7.
Major challenges encountered when trying to replace precious-metal-based electrocatalysts of the hydrogen evolution reaction (HER) in acidic media are related to the low efficiency and stability of non-precious-metal compounds. Therefore, new concepts and strategies have to be devised to develop electrocatalysts that are based on earth-abundant materials. Herein, we report a hierarchical architecture that consists of ultrathin graphene shells (only 1-3 layers) that encapsulate a uniform CoNi nanoalloy to enhance its HER performance in acidic media. The optimized catalyst exhibits high stability and activity with an onset overpotential of almost zero versus the reversible hydrogen electrode (RHE) and an overpotential of only 142 mV at 10 mA cm(-2) , which is quite close to that of commercial 40 % Pt/C catalysts. Density functional theory (DFT) calculations indicate that the ultrathin graphene shells strongly promote electron penetration from the CoNi nanoalloy to the graphene surface. With nitrogen dopants, they synergistically increase the electron density on the graphene surface, which results in superior HER activity on the graphene shells.
在酸性介质中尝试替代基于贵金属的析氢反应 (HER) 电催化剂时遇到的主要挑战与非贵金属化合物的效率和稳定性低有关。因此，必须设计新的概念和策略来开发基于丰富资源的电催化剂。在此，我们报告了一种由超薄石墨烯壳（仅 1-3 层）包裹均匀的 CoNi 纳米合金组成的分级结构，以增强其在酸性介质中的 HER 性能。优化后的催化剂表现出高稳定性和活性，相对于可逆氢电极 (RHE) 的起始过电势几乎为零，在 10 mA cm(-2) 时的过电势仅为 142 mV，这非常接近商业 40% Pt/C 催化剂。密度泛函理论 (DFT) 计算表明，超薄石墨烯壳强烈促进了电子从 CoNi 纳米合金渗透到石墨烯表面。与氮掺杂剂协同作用，它们增加了石墨烯表面的电子密度，从而在石墨烯壳上表现出优异的 HER 活性。
