It is of practical significance to use appropriate catalysts to reduce CO₂ into useful products by reasonably consuming a certain amount of electrical energy. Heterogeneous cobalt phthalocyanine/carbon nanotube (CoPc/CNT) catalyst can achieve efficient catalytic reduction performance. It has been proved that the introduction of axial coordination N atoms can effectively adjust the electronic structure of CoPc, thus regulating its activity. However, there is still a lack of systematic research on the axial coordination bond modulation CO₂RR process provided by N sources on the surface of carbon materials. In this work, pydridine with C=N-C (Py), cyanobenzene with C≡N (Cy), and aminobenzene with C-N-H (Am) were grafted onto CNT through diazotization reaction, and CoPc was loaded to form axially coordinated Co-N₅ configuration catalysts (i.e., CoPc-Py-CNT, CoPc-Cm-CNT, and CoPc-Am-CNT), and their catalytic activities were compared. CoPc-Am-CNT with Am ligand had the strongest coordination bond energy and achieved outstanding CO₂RR activity (the turnover frequency (TOF) value was 5.3 s⁻¹), which was attributed to its impaired CO₂RR energy barrier, excellent CO₂ affinity, and low mass transfer resistance. While the CO Faraday efficiency of CoPc-Am-CNT at the potential below −0.75 V vs RHE was lower than those of CoPc-Cy-CNT and CoPc-Py-CNT. This was due to the fact that the electron-donating group property of Am moved the ${\left[\text{CoPc}\right]\text{/[CoPc]}}^{\text{.-}}$ couple potential of CoPc-Am-CNT more negative, so the maximum CO Faraday efficiency of CoPc-Am-CNT could only be achieved at higher potentials (＞ −0.75 V vs RHE). This work provides new insights for the design of axial ligand catalysts and their application in eleccatalytic reduction of CO₂.

采用合适的催化剂，通过合理消耗一定的电能，将CO ₂还原成有用的产品具有现实意义。多相钴酞菁/碳纳米管（CoPc/CNT）催化剂可以实现高效的催化还原性能。已经证明，轴向配位N原子的引入可以有效地调整CoPc的电子结构，从而调节其活性。但是目前还缺乏对轴向配位键调制CO _{2的系统研究}N源在碳材料表面提供的RR过程。本工作通过重氮化反应将C=NC的吡啶（Py）、C≡N的氰基苯（Cy）和CNH的氨基苯（Am）接枝到CNT上，并负载CoPc形成轴向配位的Co-N 5_构型催化剂（即CoPc-Py-CNT、CoPc-Cm-CNT 和CoPc-Am-CNT）及其催化活性进行了比较。具有Am配体的CoPc-Am-CNT具有最强的配位键能并实现出色的CO ₂ RR活性（转换频率（TOF）值为5.3 s ^-1），这归因于其受损的CO ₂ RR能垒，优异的CO _2个亲和力好，传质阻力小。CoPc-Am-CNT 的 CO 法拉第效率在低于 -0.75 V vs RHE 的电位下低于 CoPc-Cy-CNT 和 CoPc-Py-CNT。这是由于 Am 的给电子基团性质移动了${\left[\text{CoPc}\right]\text{/[CoPc]}}^{\text{.-}}$CoPc-Am-CNT 的耦合电势更负，因此 CoPc-Am-CNT 的最大 CO 法拉第效率只能在更高的电势下实现（＞-0.75 V vs RHE）。该工作为轴向配体催化剂的设计及其在CO ₂电催化还原中的应用提供了新的思路。