Self-assembly of single metal sites embedded covalent organic frameworks into multi-dimensional nanostructures for efficient CO2 electroreduction

Morphology-controlled electrocatalysts with the ability of CO2 adsorption/activation, mass transfer, high stability and porosity are much desired in electrochemical CO2 reduction reaction (CO2RR). Here, three kinds of multi-dimensional nanostructures (i.e., hollow sphere, nanosheets and nanofibers) have been successfully produced through the modulation of porphyrin-based covalent organic frameworks (COFs) with various modulators. The obtained nanostructures with high-stability, large surface-area, and single metal sites enable efficient CO2RR into CH4. Notably, they all exhibit higher FECH4 (hollow sphere, 68.2%; nanosheet, 64.2% and nanofiber, 71.0%, -0.9 V) than COF-366-Cu (43.0%, -0.9 V) after morphology control. Noteworthy, the FECH4 of COF-366-Cu (HS) keeps higher than 52.4% over a wide potential range from -0.9 V to -1.1 V and the achieved FECH4+C2H4 (82.8%, -0.9 V) is superior to most of reported COFs and copper-based electrocatalysts. This work paves a new way in the exploration of COF-based multi-dimensional nanostructures applicable in efficient CO2RR to CH4.