Calculation of the Tafel slope and reaction order of the oxygen evolution reaction between pH 12 and pH 14 for the adsorbate mechanism, Catalysis, ChemRxiv

Despite numerous experimental and theoretical studies devoted to the oxygen evolution reaction, the mechanism of the OER on transition metal oxides remains controversial. This is in part owed to the ambiguity of electrochemical parameters of the mechanism such as the Tafel slope and reaction orders. We took the most commonly assumed adsorbate mechanism and calculated the Tafel slopes and reaction orders with respect to pH based on microkinetic analysis. We demonstrate that number of possible Tafel slopes strongly depends on a number of preceding steps and surface coverage. Furthermore, the Tafel slope becomes pH dependent when the coverage of intermediates changes with pH. These insights complicate the identification of a rate-limiting step by a single Tafel slope at a single pH. Yet, simulations of reaction orders complementary to Tafel slopes can solve some ambiguities to distinguish between possible rate-limiting steps. The most insightful information can be obtained from the low overpotential region of the Tafel plot. The simulations in this work provide clear guidelines to experimentalists for the identification of the limiting steps in the adsorbate mechanism using the observed values of the Tafel slope and reaction order in pH-dependent studies.

Tafel slopes and kinetic order of the OER at various pH levels over IrO

Comparative Electrocatalytic Oxygen Evolution Reaction Studies of Spinel NiFe2O4 and Its Nanocarbon Hybrids

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Electrocatalysis for the oxygen evolution reaction: recent development and future perspectives - Chemical Society Reviews (RSC Publishing) DOI:10.1039/C6CS00328A

Unified mechanistic understanding of CO2 reduction to CO on transition metal and single atom catalysts

Frontiers Activity and Stability of Oxides During Oxygen Evolution Reaction‐‐‐From Mechanistic Controversies Toward Relevant Electrocatalytic Descriptors

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Towards molecular understanding of local chemical environment effects in electro- and photocatalytic CO2 reduction