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Abstract Surface hydroxyls (OH) are crucial for heterogeneous catalysis in water. However, they are commonly characterized at solid–gas interfaces (e.g., FTIR, XPS, TGA), which may not represent the surface in aqueous environments. Here, the surface OH of five catalytically relevant oxides (Al2O3, ZrO2, TiO2, Fe2O3, Co3O4) are quantified by substituting them with F− ions at pH 3–10, where the surface fluoride (F) density is evaluated by XPS using the geometry factor for spherical particles. These results show that the surface F density peaks at around pH 4 across all oxides, but decreases at more basic pH due to increased OH− competition. Generally, oxides more abundant in surface OH can also accommodate more surface F, establishing F− ions as effective probes. While terminal F are likely the preferential substitution product, bridging F also appear to form at lower pH levels. Furthermore, fluoride substitution is applied to a series of Co3O4 gradually enriched with defects using pulsed laser defect engineering in liquid (PUDEL). This approach reveals a linear correlation between laser processing and surface OH density, which aligns with a previously observed improvement in OER activity, and is supported by additional DFT calculations here. This work will stimulate further studies adopting fluoride substitution to better understand the relationship between surface chemistry and catalytic processes in aqueous environments.

Abstract The present application note summarizes an advanced methodology that allows for deriving potential‐dependent volcano curves for energy storage and conversion processes. The conventional approach relies on the combination of density functional theory calculations and scaling relations for a single mechanistic pathway as well as a discussion of electrocatalytic activity by means of the potential‐determining step, determined at the equilibrium potential of the reaction. Herein, it is illustrated how several reaction mechanisms can be factored into the volcano curve and how the rate‐determining step based on the descriptor Gmax(U) can be derived by a rigorous thermodynamic analysis of adsorption free energies fed by a data‐inspired methodology.

Abstract Electrochemical carbon dioxide reduction (CO2RR) is gaining momentum as an effective process to capture and convert CO2 into valuable chemicals and fuels, as well as to contribute reducing greenhouse gas emissions. Two‐dimensional transition metal carbides and/or nitrides (MXenes) are increasingly attracting attention as CO2RR electrocatalysts due to their enhanced chemical activity and selectivity, overcoming limitations of traditional metal CO2RR electrocatalysts, and likely breaking the scaling relations of reaction intermediates toward the desired product. The present concept reviews the state‐of‐the‐art in the computational description of CO2RR on MXenes, going from CO2 activation on pristine models to different surface terminations, and discuss possible ways to tune the catalytic activity and selectivity, including doping, defects, supported single metal atoms, solvent effects, and electric field effects, while putting in the spotlight prospects by including kinetic aspects.