The data distribution relative to the PET reactions is multimodal, as shown in Figure (e). Each reaction showed a dominant peak centered at a positive value. There is a resemblance between the energy spectrum of PET15 and PET37 with that of PET04, respectively, and PET48. Similarities in the proton states of the reactants may explain it. E 0 ranges from -1.222 to 2.722 V SHE .