Identification of Active Sites for Ammonia Electrosynthesis on Ruthenium
Identification of Active Sites for Ammonia Electrosynthesis on Ruthenium
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DOI：
10.1021/acsenergylett.2c02175
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发表时间：
2022-11
影响因子：
22
通讯作者：
Lin Hu;H. Pillai;Corbin Feit;Kaige Shi;Zhengning Gao;P. Banerjee;Hongliang Xin;Xiaofeng Feng
中科院分区：
文献类型：
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作者：
Lin Hu;H. Pillai;Corbin Feit;Kaige Shi;Zhengning Gao;P. Banerjee;Hongliang Xin;Xiaofeng Feng
电化学n2还原反应（NRR）为可持续生产nh3提供了一条有吸引力的途径，但由于缺乏对其结构-活性关系和活性位点的了解，阻碍了NRR电催化剂的设计。在这里，我们报告了通过原子层沉积制备的Ru纳米颗粒上的NRR的显著的尺寸依赖性活性。当Ru粒径从2.1 nm增大到8.4 nm时，质量活性和生成nh3的法拉第效率均单调下降，而比活性（Ru表面积归一化）在3.8 nm时达到最高值，而在8.4 nm时下降了5倍。密度泛函数理论（DFT）计算和基本步骤的自由能分析表明，Ru D5step位点在~ 4 nm的粒子上具有最大的居群，是Ru上NRR的活性位点，因为与其他表面位点相比，它更有利于*N2H中间体的吸附，而不会受到* nh2中间体的污染。
Electrochemical N2reduction reaction (NRR) provides an attractive approach toward sustainable NH3production, while the design of electrocatalysts for NRR is hindered by the lack of knowledge of the structure–activity relationships and active sites. Here we report a prominent size-dependent activity for the NRR on Ru nanoparticles prepared by atomic layer deposition. As the Ru particle size increased from 2.1 to 8.4 nm, the mass activity and Faradaic efficiency for NH3production both decreased monotonically, while the specific (Ru-surface-area-normalized) activity reached the highest value on 3.8 nm Ru nanoparticles but declined by 5-fold on 8.4 nm Ru nanoparticles. Density functional theory (DFT) calculations and free energy analysis of elementary steps revealed the Ru D5step site, with its maximal population at ∼4 nm particles, as the active site for the NRR on Ru, because it favors the adsorption of the *N2H intermediate compared to other surface sites while not getting poisoned by the *NH2intermediate.