Revealing the hidden performance of metal phthalocyanines for CO_2 reduction electrocatalysis by hybridization with carbon nanotubes

Metal phthalocyanines (MePcs) have been considered as promising catalysts for CO_2 reduction electrocatalysis due to high turnover frequency and structural tunability. However, their performance is often limited by low current density and the performance of some systems is controversial. Here, we report a carbon nanotube (CNT) hybridization approach to study the electrocatalytic performance of MePcs (Me = Co, Fe and Mn). MePc molecules are anchored on CNTs to form the hybrid materials without noticeable molecular aggregations. The MePc/CNT hybrids show higher activities and better stabilities than their molecular counterparts. FePc/CNT is slightly less active than CoPc/CNT, but it could deliver higher Faradaic efficiencies for CO production at low overpotentials. In contrast, the catalytic performance of MePc molecules directly loaded on substrate is hindered by molecular aggregation, especially for FePc and MnPc. Our results suggest that carbon nanotube hybridization is an efficient approach to construct advanced MePc electrocatalysts and to understand their catalytic performance.