LASPAI-Assisted Mechanistic Investigation of Carbon Poisoning in Molecular Copper-Catalyzed CO2 Reduction

Strong retention of coordinated CO can divert molecular CO2 reduction from product release toward persistent carbon-containing species and catalyst deactivation. We examine this competition in a Cu(II)-derived Cudpk system using electrochemistry–electrospray ionization mass spectrometry (EC-ESI-MS), collision-induced dissociation (CID) and AI-assisted pathway simulation. Time-resolved EC-ESI-MS during the potential-pulse sequence detected Cudpk ions assigned to -–CO, –COH, –CHOH and –CH-associated compositions. In separate post-electrolysis solution samples, an m/z = 260 CH-associated ion was detected after constant-potential operation but was not obvious after approximately 16 h of pulsed operation. Double-ended surface walking (DESW) searches on LASPAI use a generalized global neural network (GGNN) potential to evaluate energies and forces. The resulting profile places a high energetic cost on CO release and identifies a competing route from retained CO toward a Cu-bound carbon state. Pulsed operation resolves this contradiction: periodic potential pulses suppress the accumulation of residual carbon-containing species, thereby maintaining the turnover of the CO formation reaction. The AI-derived energy profile and pulse-dependent mass spectrometry data support a proposed deactivation pathway involving further conversion of strongly retained CO into persistent carbon-associated species. The reduced persistence of CH-associated ions after pulsed operation, together with sustained CO production, is consistent with mitigation of this pathway.