Fig. shows the investigated reaction scheme for CO 2 reduction to either CO or HCOOH, which occurs via two proton-coupled electron transfer (PCET) reactions. Atomic visualizations of the intermediates are shown to the right. The first PCET is the conversion of CO 2 to one of the competing intermediates, either *COOH (Eq. 1) or HCOO** (Eq. 2), the activation step: