Electrochemical reactions depend on the electrochemical interface between the electrode surfaces and the electrolytes. To control and advance electrochemical reactions there is a need to develop realistic simulation models of the electrochemical interface to understand the interface from an atomistic point‐of‐view. Here we present a method for obtaining thermodynamic realistic interface structures, a procedure we use to derive specific coverages and to obtain ab initio simulated cyclic voltammograms. As a case study, the method and procedure is applied in a matrix study of three Cu facets in three different electrolytes. The results have been validated by direct comparison to experimental cyclic voltammograms. The alkaline (NaOH) cyclic voltammograms are described by H* and OH*, while in neutral medium (KHCO3) the CO3* species are dominating and in acidic (KCl) the Cl* species prevail. An almost one‐to‐one mapping is observed from simulation to experiments giving an atomistic understanding of the interface structure of the Cu facets. Atomistic understanding of the interface at relevant eletrolyte conditions will further allow realistic modelling of electrochemical reactions of importance for future eletrocatalytic studies.

Aiming to reduce anthropogenic CO2 emissions, there is an urgent demand to develop more efficient and affordable technologies which convert CO2 into valuable feedstock molecules. The use of renewable electricity is a promising and sustainable approach to overcome this environmental issue, while producing valuable chemicals and clean fuels. However, the CO2 electroreduction reaction (CO2RR) still shows two main gaps: poor selectivity and required large overpotentials make the process not profitable enough. To overcome these challenges, model studies on single‐crystalline surfaces aiming to find the relations between surface structure/electrolyte interactions and activity/selectivity are necessary. In these model studies, tuning the electrolyte composition is also key for the fundamental understanding of the CO2RR. In this review, we first discuss the structure‐activity‐selectivity relations from studies on well‐ordered surfaces, i. e., single crystalline electrodes, for the CO2RR. We then summarise the role of the electrolyte, presenting work on classical aqueous solvents as well as non‐aqueous electrolytes such as ionic liquids. We illustrate the importance of carrying out studies on well‐defined electrified interfaces in order to get deep fundamental insights on the mechanism of the CO2RR, as well as scaling the process for real applications. Ultimately, this knowledge will be essential to rationally design the catalyst with tailored activity and selectivity for CO2 reduction.

Proton exchange membrane water electrolysers are very promising renewable energy conversion devices to produce hydrogen from sustainable feedstocks. These devices are mainly limited by the sluggish kinetics of the oxygen evolution reaction (OER). Therefore, efficient catalysts in acidic media that allow operating at low overpotential are necessary. Ir‐based nanoparticles are both active and stable for the OER. Surfactants are widely used in the preparation of nanoparticle colloids. A severe drawback for catalysis is the need to remove surfactants by typically costly, hazardous, time and/or energy consuming steps. Herein we present a modified approach of the polyol synthesis that consists of a simple surfactant‐free and NaOH‐free synthesis of Ir nanoparticles in ethylene glycol leading to colloidal nanoparticles of ca. 2.5 nm in diameter. The benefits and drawbacks of the surfactant‐free synthesis are illustrated by comparison with commercial Ir black nanoparticles and Ir nanoparticles obtained using surfactant for the electrocatalytic OER in acidic media.

Proton exchange membrane water electrolysers are very promising renewable energy conversion devices that produce hydrogen from sustainable feedstocks. These devices are mainly limited by the sluggish kinetics of the oxygen evolution reaction (OER). Ir‐based nanoparticles are both reasonably active and stable for the OER in acidic media. The electrolyte composition and the pH may play a crucial role in electrocatalysis, yet they have been widely overlooked for the OER. Herein, we present a study on the effects of the composition and concentration of the electrolyte on commercial Ir black nanoparticles using concentrations of 0.05 M, 0.1 M and 0.5 M of both sulphuric and perchloric acid. The results show an important effect of the electrolyte composition on the catalytic performance of the Ir nanoparticles. The concentration of H2SO4 interferes on the oxidation of Ir and decreases the catalytic performance of the catalyst. HClO4 does not show strong interferences in the electrochemistry of Ir. Higher catalytic performances are observed in HClO4 electrolytes in comparison to H2SO4 with little effect of the concentration of HClO4.

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