Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China.
Nanoscale. 2019 Mar 14;11(11):4911-4917. doi: 10.1039/c8nr10236h.
Nitrogen-doped carbon materials are promising electrocatalysts for electroreduction of CO2. However, the low current density and moderate faradaic efficiency of these materials limit their practical application. Here, we report the MOF-derived nitrogen-doped nanoporous carbon (NC) as a highly efficient and stable electrocatalyst for the conversion of CO2 to CO. The NC catalysts were prepared by calcining ZIF-8 at different temperatures in argon (Ar). The catalytic performances show that the higher pyrolysis temperature result in a better CO2 electroreduction activity of the catalysts. The NC catalyst with the best performance achieves high selectivity with 95.4% CO faradaic efficiency (FE) at -0.5 V vs. reversible hydrogen electrode (RHE). The catalyst also maintains long-term stability of 20 h operation, after which the FE of CO is still greater than 90%. The experiments show that higher pyrolysis temperature reduces the total nitrogen (N) but changes the nature and density of N defects. Density functional theory calculations reveal that higher pyrolysis temperature leads to enhanced activity by promoting the formation of low multiple pyridinic N, which provides more efficient active sites.
氮掺杂碳材料是一种很有前途的 CO2 电还原电催化剂。然而，这些材料的低电流密度和中等法拉第效率限制了它们的实际应用。在这里，我们报告了一种由 MOF 衍生的氮掺杂纳米多孔碳（NC）作为一种高效稳定的 CO2 电还原为 CO 的电催化剂。NC 催化剂是通过在氩气（Ar）中在不同温度下煅烧 ZIF-8 制备的。催化性能表明，较高的热解温度导致催化剂的 CO2 电还原活性更好。性能最佳的 NC 催化剂在相对于可逆氢电极（RHE）为-0.5 V 时，达到了 95.4% CO 法拉第效率（FE）的高选择性。该催化剂还能稳定运行 20 小时，之后 CO 的 FE 仍大于 90%。实验表明，较高的热解温度会降低总氮（N）含量，但会改变 N 缺陷的性质和密度。密度泛函理论计算表明，较高的热解温度通过促进低多重吡啶 N 的形成来提高活性，从而提供了更多高效的活性位点。
