Table S5.

Work function (in electronvolts) of the initial state (Φ₀), transition state (Φ_TS), and final state (Φ₁) for various reduction steps of CH₄ formation on Cu(100) at pH 7 and 298 K

ID	Reaction equation	Φ0, eV	ΦTS, eV	Φ1, eV
1	$\text{*CO}+\text{H*}\to \text{*CHO}$	3.48 (0.33)	3.49 (0.23)	3.59 (0.24)
1a	$\text{*CO}+{\text{H}}_2\text{O}+e^{-}\to \text{*CHO}+{\text{OH}}^{-}$	3.48 (0.33)	3.60 (0.29)	3.80 (0.27)
1b	$\text{*CO}+{\text{H}}_2\text{O}+e^{-}\to \text{*COH}+{\text{OH}}^{-}$	3.48 (0.33)	3.52 (0.24)	3.75 (0.30)
2	$\text{*CHO}+{\text{H}}_2\text{O}+e^{-}\to \text{*CHOH}+{\text{OH}}^{-}$	3.38 (0.34)	3.48 (0.32)	3.66 (0.20)
2a	$\text{*CHO}+\text{H*}\to {\text{CH}}_2\text{O}$	3.38 (0.34)	3.49 (0.32)	3.47 (0.27)
3	$\text{*CHOH}+e^{-}\stackrel{{\text{H}}_2\text{O}}{\to }\text{*CH}+{\text{OH}}^{-}$	3.36 (0.34)	3.55 (0.24)	3.80 (0.34)
3a	$\text{*CHOH}+\text{H*}\to {\text{*CH}}_2\text{OH}$	3.36 (0.34)	3.47 (0.31)	3.49 (0.21)
4	$\text{*CH}+{\text{H}}_2\text{O}+e^{-}\to {\text{*CH}}_2+{\text{OH}}^{-}$	3.23 (0.29)	3.42 (0.25)	3.70 (0.33)
4a	$\text{*CH}+\text{H*}\to {\text{*CH}}_2$	3.23 (0.29)	3.28 (0.32)	3.39 (0.36)
5	${\text{*CH}}_2+{\text{H}}_2\text{O}+e^{-}\to {\text{*CH}}_3+{\text{OH}}^{-}$	3.22 (0.29)	3.41 (0.23)	3.67 (0.29)
5a	${\text{*CH}}_2+\text{H*}\to {\text{*CH}}_3$	3.22 (0.29)	3.25 (0.35)	3.32 (0.33)
6	${\text{*CH}}_3+{\text{H}}_2\text{O}+e^{-}\to {\text{CH}}_4+{\text{OH}}^{-}$	3.26 (0.22)	3.42 (0.29)	3.63 (0.36)
6a	${\text{*CH}}_3+\text{H*}\to {\text{CH}}_4$	3.26 (0.22)	3.38 (0.31)	3.40 (0.22)