Fig. 3: A conceptual electric series circuit illustrates a mixed-potential-driven catalytic reaction.
From: Theoretical framework for mixed-potential-driven catalysis
The internal total voltage \({\phi }_{2}^{{{{{{\rm{eq}}}}}}}-{\phi }_{1}^{{{{{{\rm{eq}}}}}}}\) is due to the Gibbs free energy drop \(-\Delta {G}_{{{{{{\rm{r}}}}}}}\) across the entire mixed-potential-driven catalytic reaction. The charge-transfer resistance (\({r}_{1}\) and \({r}_{2}\)), proportional to the reciprocal of the exchange current, plays a role similar to electrical resistors in a circuit. The voltage drops, \({i}^{{{{{{\rm{mix}}}}}}}{r}_{1}\) and \({i}^{{{{{{\rm{mix}}}}}}}{r}_{2}\), signifies the overpotentials \(|{\eta }_{1}^{{{{{{\rm{mix}}}}}}}|\) and \(|{\eta }_{2}^{{{{{{\rm{mix}}}}}}}|\), following the voltage divider rule. The energy utilized for driving reactions 1 and 2 eventually transforms into Joule heat (\(\eta i\)).
