Promoting electrocatalytic CO2 reduction on nitrogen-doped carbon with sulfur addition
Promoting electrocatalytic CO2 reduction on nitrogen-doped carbon with sulfur addition
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DOI：
10.1016/j.apcatb.2019.04.025
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发表时间：
2019-09-05
影响因子：
22.1
通讯作者：
Li, Ying
中科院分区：
文献类型：
--
作者：
Pan, Fuping;Li, Boyang;Li, Ying
CO2在无金属N掺杂碳（N-C）催化剂上的电化学还原提供了将CO2转化为增值燃料的新兴途径。然而，当在低过电位下操作时，其效率差。实验结果表明，硫的添加可以显著提高N-C催化剂的CO2还原活性和选择性。在490 mV的低过电位下，N，S共掺杂碳催化剂的CO法拉第效率为92%，CO电流为2.63 mA cm（-2），明显优于无S的N-C催化剂。通过将掺杂剂构型与模型催化剂的催化性能相关联并结合理论密度泛函理论（DFT）计算，我们揭示了在N-C中掺入S导致产生更高密度的吡啶N，其作为CO2活化的决定活性位点。此外，S掺杂剂通过降低关键中间体 * COOH形成的自由能垒而显著促进吡啶和石墨N的催化反应性和选择性。本工作中报道的双掺杂促进效应的实验结果和理论理解为设计用于CO2转化的高性能碳催化剂提供了见解。
Electrochemical reduction of CO2 on metal-free N-doped carbon (N-C) catalysts offers an emerging route to transform CO2 into value-added fuels. However, it suffers poor efficiency when operated at low overpotentials. Herein, we demonstrated that sulfur (S) addition could greatly enhance catalytic CO2 reduction activity and selectivity of N-C. The N,S-codoped carbon catalysts exhibited a high CO Faradaic efficiency of 92% and a CO current of 2.63 mA cm(-2) at a low overpotential of 490 mV, much better than that of the S-free N-C counterpart. By correlating dopant configurations with catalytic performance of model catalysts and combining theoretical density functional theory (DFT) calculations, we revealed that incorporating S in N-C leads to the generation of a higher density of pyridinic N that serves as the determining active site for CO2 activation. In addition, S dopants significantly promote the catalytic reactivity and selectivity of pyridinic and graphitic N by decreasing the free energy barrier for key intermediate *COOH formation. The experimental findings and theoretical understanding of the dual-doping promotion effects reported in this work have provided insights on designing high-performance carbon catalysts for CO2 conversion.