Theoretical investigations of electrochemical CO2 reduction by transition metals anchored on CNTs,Sustainable Energy & Fuels

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Theoretical investigations of electrochemical CO2 reduction by transition metals anchored on CNTs
Sustainable Energy & Fuels ( IF 5.0 ) Pub Date : 2020-10-14 , DOI: 10.1039/d0se01127d
Chengcheng Ao _{1,

2,

3,

4} , Wei Zhao _{1,

2,

3,

4} , Shanshan Ruan _{1,

2,

3,

4} , Siyu Qian _{1,

2,

3,

4} , Yi Liu _{1,

2,

3,

4} , Lei Wang _{1,

2,

3,

4} , Lidong Zhang _{1,

2,

3,

4,

5}

Affiliation

Transition metals supported on nitrogen doped carbon materials are a class of promising electrochemical catalysts toward electrochemical CO₂ reduction reactions (CO₂RR) that have exhibited excellent catalytic performance. Herein, M–N₄ (M = Fe, Co and Ni) coordination structures embedded in carbon nanotubes (CNTs) were constructed to explore detailed mechanisms as electrocatalysts for CO₂RR via density functional theory (DFT) calculations. Nitrogen atoms of coordination structures rather than only single transition metal atoms were demonstrated to be effective active sites toward CO₂RR. For two possible pathways of the first step, forming *COOH or *OCHO, according to the catalytic activity of nitrogen atoms to the H atom, *COOH generation was facilitated in terms of kinetics over *OCHO in three systems. Meantime, it is suggested that the products of electrochemical CO₂RR on the three catalysts are heavily dependent on the interaction of CO and the catalysts. Ni–N₄/CNT exhibits a considerable selectivity to CO due to the weak interaction of CO and the substrates with a limiting potential of 1.79 V. On the contrary, CO prefers to remain on Fe–N₄/CNT due to the strong binding energy of CO adsorbed on Fe–N₄/CNT. Then the CO of the Fe–N₄/CNT system undergoes further hydrogenation to produce CH₃OH and CH₄ at the same limiting potential of 0.68 V, indicating that there is no distinct selectivity in forming CH₃OH and CH₄. Nevertheless, the limiting potentials of CO, CH₃OH and CH₄ on Co–N₄/CNT are totally different, 0.43 V, 0.56 V and 0.87 V, respectively. In particular, CO₂RR to CO on Co–N₄/CNT has the lowest potential limit. Thus, Co–N₄/CNT has a considerable potential as the catalyst for electrochemical CO₂RR. In addition, the catalysts of Ni single atoms, unsaturated coordination with nitrogen atoms, edge-anchored on CNTs were investigated for their activity for the CO₂RR. Our comprehensive understanding of M–N₄/CNT materials may be instructive and meaningful to design advanced catalysts from nonprecious metals for electrochemical CO₂RR.

中文翻译：

固定在CNT上的过渡金属对电化学CO2还原的理论研究

负载在氮掺杂碳材料上的过渡金属是一类有前途的电化学催化剂，可用于表现出出色催化性能的电化学CO ₂还原反应（CO ₂ RR）。本文中，构建了嵌入碳纳米管（CNT）中的M–N ₄（M = Fe，Co和Ni）配位结构，以通过密度泛函理论（DFT）计算来探索作为CO ₂ RR电催化剂的详细机理。配位结构的氮原子而不是单个过渡金属原子被证明是有效的CO ₂活性位点RR。对于第一步的两个可能的途径，形成* COOH或* OCHO，根据氮原子对H原子的催化活性，在动力学上，在三个系统中* COOH的生成优于* OCHO。同时，提出三种催化剂上的电化学CO ₂ RR产物在很大程度上取决于CO和催化剂的相互作用。Ni–N ₄ / CNT对CO表现出相当大的选择性，这是因为CO与底物之间的弱相互作用，极限电位为1.79V。相反，由于结合力强，CO倾向于保留在Fe–N ₄ / CNT上CO吸附在Fe–N ₄ / CNT上的能量。然后是Fe–N ₄的CO/ CNT系统进一步加氢以在相同的极限电势0.68 V下生成CH ₃ OH和CH ₄，表明形成CH ₃ OH和CH _4时没有明显的选择性。但是，CO，CH ₃ OH和CH ₄在Co–N ₄ / CNT上的极限电位完全不同，分别为0.43 V，0.56 V和0.87V。特别是，Co–N ₄ / CNT上的CO ₂ RR对CO的最低电位极限。因此，Co–N ₄ / CNT具有作为电化学CO ₂催化剂的巨大潜力。RR。另外，研究了碳纳米管边缘固定在碳纳米管上的Ni单原子，与氮原子不饱和配位的催化剂对CO ₂ RR的活性。我们对M–N ₄ / CNT材料的全面理解对于用非贵金属设计用于电化学CO ₂ RR的高级催化剂可能具有指导意义和意义。

更新日期：2020-11-03

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