Figure 2.

Kinetic analysis of Co-based tetrapyrroles. (A, D) Structures of catalysts studied: cobalt phthalocyanine (CoPc, A) and cobalt tetraphenyl porphyrin (CoTPP, D). (B, E) Apparent bicarbonate order dependencies at different voltages for CoPc (B) and CoTPP (E). (C, F) Apparent CO₂ order dependencies at different voltages for CoPc (C) and CoTPP (F). Points represent experimental data, and lines represent model fits. Error bars represent standard deviation with n ≥ 3. For all experiments, voltages reported vs SHE, total ionic strength held constant using NaClO₄, and CO₂ at 1 atm. (G) Mechanistic framework that can explain the kinetic observations. Salient phenomena at less reductive voltages are displayed in purple, and salient phenomena at more reductive voltages are displayed in yellow.