Efficient and Selective Electroreduction of CO2 by Single-Atom Catalyst Two-Dimensional TM-Pc Monolayers

Electrochemical CO2 reduction to value-added fuels and chemicals provides a clean and efficient way to mitigate energy shortages and to lower the global carbon footprint if one could find highly stable, efficient, selective, and low-cost electrocatalysts. However, this remains a huge challenge. In this work, the catalytic performance of transition metal-phthalocyanine (TM-Pc) monolayers as single-atom catalysts for the electroreduction of CO2 was systematically investigated by spin-polarized density functional theory (DFT) calculations. Our results show that the bonding of single metal atoms with Pc can be large enough for the individual atoms to be uniformly dispersed and anchored in a modified 2D TM-Pc monolayer. Considering the competing hydrogen evolution reaction, TM-Pc has a good hydrogen evolution inhibition. The main CRR reduction products of Sc-Pc, Ti-Pc, V-Pc, and Fe-Pc monolayers are CH4. For Cr-Pc, Mn-Pc, and Zn-Pc monolayers, HCOOH is dominant, while for Co-Pc, HCHO is predicted. Except for the Sc-Pc, Ti-Pc, and V-Pc monolayers by (with too large overpotentials, exceeding 1 V), the reduction overpotential of other TM-Pc catalysts are in the range of 0.017-0.819 V, among them Mn-Pc has the lowest overpotential (0.017 V) and Fe-Pc has the highest overpotential (0.819 V). These were all lower than the overpotentials of well-studied copper which has the best catalytic performance. Therefore, our work may open up new avenues for the development of highly efficient catalytic materials for CO2 reduction.