Article Ru/RuO 2 Nanoparticle Composites with N-Doped Reduced Graphe...
In this article they said: (( According to Figure 4a and 4b, the Ru/RuO2@N-rGO possessed the highest OER performance, requiring the smallest overpotential of 255 mV to achieve a current density of 10 mA cm−2. )) in alkaline media ( KOH 1M ) and (( The electrocatalytic performance of Ru/RuO2@N-rGO in acidic solution (H2SO4 0.5 M ) was also evaluated for OER. A relatively low overpotentials of 234 mV (OER) were found at 10 mA cm−2. ))
Electrochemical water splitting:
Reduction at cathode: 2 H+(aq) + 2e− → H2(g)
Oxidation at anode: 2 H2O(l) → O2(g) + 4 H+(aq) + 4e−
The structures of Ru/RuO2@N-rGO in alkaline and in acidic media are different. Two different catalytic systems may have the similar performance under different conditions.
Dear Yurii V Geletii your opinion seems to be correct and it is reasonable but would you mind explain it more please. I cannot completely understand the difference between the structures in this two conditions. I know the oxidation state of the transition metal and transition metal species forms in solution are depend on PH and concentration of the metal salt solution. Are you leading me to this concept? or Do you have another opinion?
Dear Tina Sung of course the mechanisms are different in this two mediums and that is the reason for that water splitting need different energies in different PHs. We already know OER in alkaline medium needs less energy than acidic medium. So we can conclude that the OER can occur easier in alkaline medium. Hence here is the question: How is it possible for a catalyst To catalyze the OER in acidic media with less overpotential than in alkaline media?
Sina Safavi You are correct that " the oxidation state of the transition metal and transition metal species forms in solution are depend on PH and concentration of the metal salt solution." " Are you leading me to this concept?" Yes
When you are looking at overpotential of OER, you have to keep in mind the second half reaction, HER. The potential required for water splitting is pH independent, 1.24 V. In alkaline medium you have lower overpotential for OER but higher for HER
Thank you so much dear Yurii V Geletii . Now it gets completely clear for me. Your answers are always the best.
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