Fig. 2: Redox characterization of the [Fe(CN)6]3−/4− mediator in seawater.
From: Redox-mediated decoupled seawater direct splitting for H2 production
The experiments were carried out at room temperature (~25 °C). The carbon rod electrode serving as the counter electrode, and the Ag/AgCl electrode (in saturated KCl solution) acting as the reference electrode. a Redox reaction of [Fe(CN)6]3−/4−, gray, yellow, green, and orange balls represent the C atoms, Fe atoms, N atoms, and electrons, respectively. b CV curves of [Fe(CN)6]3−/4− in 1 M KOH, 1 M KOH + 0.5 M NaCl, and 1 M KOH + seawater at 5 mV s−1 and LSV curves without [Fe(CN)6]3−in the above electrolytes without iR compensation. The working electrode is a glassy carbon electrode. c CV curves at different scan rates in 1 M KOH + seawater and d the relationship between peak currents in 1 M KOH + seawater and ω1/2. e CV curves of [Fe(CN)6]3−/4− in 1 M KOH + seawater over 5000 cycles at 50 mV s−1. f RDE experiment of [Fe(CN)6]3−/4− in 1 M KOH + seawater from 100 to 2500 rpm. g Levich plot of the measured limiting current versus the square root of the rotation rate (ω0.5). h Koutecky–Levich plot at different overpotentials from 20 to 148 mV. i Fitting the Tafel plot with the Butler‒Volmer equation; here, the logarithm of the kinetically limited current is plotted against the overpotential.
