Fig. 6: Volcano plot of the free energies of reaction for acetylene reduction to 1,3-BD.
From: Selective electroreduction of acetylene to 1,3-butadiene on iodide-induced Cuδ+–Cu0 sites
The computed reaction free energies are plotted against the adsorption free energies of acetylene (\(\Delta {G}_{\mathrm{{C}_{2}{H}_{2}}}\)) on various electrodes. The active sites included are stripe, stripe + *O + *I, stripe + *O + *Cl, stripe + *O + *HSO4, stripe + *I and stripe + *O on copper, nickel and silver electrodes at −0.85 V versus SHE. The initial hydrogenation step is limiting on the right side of the volcano (green), and the coupling step is limiting on the left side (orange). The colour of the points indicates their limiting step, and the active sites are shown in Fig. 5. Inset: summary of the active sites of each metal. The data points represent the average activities and adsorption energies of each catalyst with different coadsorbed species, while the error bars represent the s.d. of the data in the main panel for each catalyst. Average data for Cu2O(111) are also provided for comparison (see also Supplementary Tables 20–22). The vertical line marks the energy range where acetylene is preferentially adsorbed (left-hand side) or in the gas phase (right-hand side).
