Electrolysis

Photocatalysis

Electron transfer

Catalysis

Electrolyte

Physical chemistry

Inorganic chemistry

Biochemistry

Oxygen evolution

Tafel equation

Electrode

Electrolysis of water

Chemistry

Water splitting

Electrochemistry

Photochemistry

Electrocatalyst

Journal of Catalysis

Water electrolysis driven by electrical power generated from renewable energy sources will play a pivotal role in future sustainable societies, which requires adaptation of various reaction conditions as well as electrolyte identities. Regardless, the anodic half-reaction of the oxygen evolution reaction (OER) is considered a kinetic bottleneck. This study provides quantitative description of the OER kinetics based on rigorous microkinetic analyses including Tafel analysis, isotope effects and temperature dependence using an IrOx electrocatalyst in unbuffered solution at varying pH levels. The diffusional constraints of H+/OH− determine three distinctive kinetic regimes in the pH-potential-current relationships: below pH 5, between pH 5 and 10, and above pH 10 at appreciable current densities on the order of 1 mA cm−2. When shifting from alkaline to acidic solution, the complete consumption of local OH− near the electrode surface switches the OER proceeding as the oxidation of OH− to that of the water molecul...

Microkinetic assessment of electrocatalytic oxygen evolution reaction over iridium oxide in unbuffered conditions