Efficient electron transmission in covalent organic framework nanosheets for highly active electrocatalytic carbon dioxide reduction

Efficient conversion of carbon dioxide (CO(2)) into value-added products is essential for clean energy research. Design of stable, selective, and powerful electrocatalysts for CO(2) reduction reaction (CO(2)RR) is highly desirable yet largely unmet. In this work, a series of metalloporphyrin-tetrathiafulvalene based covalent organic frameworks (M-TTCOFs) are designed. Tetrathiafulvalene, serving as electron donator or carrier, can construct an oriented electron transmission pathway with metalloporphyrin. Thus-obtained M-TTCOFs can serve as electrocatalysts with high FE(CO) (91.3%, −0.7 V) and possess high cycling stability (>40 h). In addition, after exfoliation, the FE(CO) value of Co-TTCOF nanosheets (~5 nm) is higher than 90% in a wide potential range from −0.6 to −0.9 V and the maximum FE(CO) can reach up to almost 100% (99.7%, −0.8 V). The electrocatalytic CO(2)RR mechanisms are discussed and revealed by density functional theory calculations. This work paves a new way in exploring porous crystalline materials in electrocatalytic CO(2)RR.