New insights into the enhanced CO2RR durability caused by electron-donating substitution of heterogeneous CoPc

Abstract

Heterogeneous CoPc achieved the breakthrough CO₂RR methanol production, yet the long-term electrolytic durability remains challenging. Electron-donating amino substitution on the phthalocyanine ligand is a great approach to improve durability, but the underlying mechanism is controversial. Moreover, the accompanying decreased methanol selectivity is puzzling, hindering the simultaneous selectivity and durability improvement. Herein, we clarify the origin of enhanced durability and decreased selectivity via grand-canonical DFT calculations and propose a method to simultaneously improve both. The methanol activity retention along with ligand hydrogenation based on the “unfolding–folding” scheme leads to improved durability. “Unfolding” refers to the separation of hydrogenation and NH₂ substitution effects. Hydrogenation changes the potential-determining step, while NH₂ substitution poses opposite electronic effects. “Folding” the two aspects results in enhanced durability. Reduced selectivity is caused by the crossover point potential, which reverses methanol activity. Positively shifting the crossover point by changing the capacitance and the PZC is revealed to enhance both selectivity and durability. These findings agree well with experimental results, offering valuable insights into long-term and highly selective CO₂ reduction.