Table 1.

Electrochemical redox potentials (E° vs. NHE, pH = 7.0) for CO₂ reduction into a variety of useful chemical products [4,40,41].

No.	Reactions	E° vs. NHE (V)
1	CO2 + 2H+ + 2e− → HCOOH	−0.61 V
2	CO2 + 2H+ + 2e− → CO + H2O	−0.53 V
3	CO2 + 4H+ + 4e− → HCHO + H2O	−0.48 V
4	CO2 + 6H+ + 6e− → CH3OH + H2O	−0.38 V
5	CO2 + 8H+ + 8e− → CH4 + 2H2O	−0.24 V
6	2H+ + 2e− → H2	−0.41 V
Water Oxidation Reactio
7	2H2O → O2 + 4H+ + 4e−	+0.81V