We report a comparative study on the influence of generic electrochemical activation–oxidation protocols on the resulting surface oxides of Ir(1 1 1) and (1 1 0) and Ru(0 0 0 1) single crystals and their electrocatalytic reactivity for the oxygen evolution reaction. Well‐defined single‐crystal electrodes were prepared in a custom‐made chamber that combines inductive thermal annealing and electrochemistry. The clean surfaces were analyzed for their electrocatalytic oxygen evolution activities and oxidation behavior. Three different oxidation protocols were used, which revealed a strong activity dependence on the duration and upper potential limit of the electrochemical oxidation. The resulting changes of the surface were followed by using cyclic voltammetry and impedance spectroscopy. Important differences between the two faces of Ir in terms of surface morphology of the formed oxide were identified, which allowed us to draw conclusions for preferable crystal faces in nanoparticle catalysts.

The alteration of electrocatalytic surfaces with adatoms lead to structural and electronic modifications promoting adsorption, desorption, and reactive processes. This study explores the potentiostatic electrodeposition process of Ni onto polycrystalline Ir (Irpoly) and assesses the electrocatalytic properties of the resulting bimetallic surfaces. The electrodeposition resulted in bimetallic Ni overlayer (OL) structures and in combination with controlled thermal post-deposition annealing in bimetallic near-surface alloys (NSA). The catalytic oxygen evolution reaction (OER) activity of these two different Ni-modified catalysts is assessed and compared to a pristine, unmodified Irpoly. An overlayer of Ni on Irpoly showed superior performance in both acidic and alkaline milieu. The reductive annealing of the OL produced a NSA of Ni, which demonstrated enhanced stability in an acidic environment. The remarkable activity and stability improvement of Ir by Ni modification makes both systems efficient electrocatalysts for water oxidation. The roughness factor of Irpoly is also reported. With the amount of deposited Ni determined by inductively coupled plasma mass spectrometry (ICP-MS) and a degree of coverage (monolayer) in the dependence of deposition potential is established. The density functional theory (DFT) assisted evaluation of H adsorption on Irpoly enables determination of the preferred Ni deposition sites on the three low-index surfaces (111), (110), and (100).

Iridium (Ir) oxide is known to be one of the best electrocatalysts for the oxygen evolution reaction (OER) in acidic media. Ir oxide-based materials are thus of great scientific interest in current research on electrochemical energy conversion. In the present study, we applied Ir metal films as model systems for electrochemical water splitting, obtained by inductive heating in a custom-made setup using two different synthesis approaches. X-ray photoelectron spectroscopy (XPS) and selected area electron diffraction (SAED) confirmed that all films were consistently metallic. The effects of reductive heating time of calcined and uncalcined Ir acetate films on OER activity were investigated using a rotating disk electrode (RDE) setup. The morphology of all films was determined by scanning electron microscopy (SEM). The films directly reduced from the acetate precursor exhibited a strong variability of their morphology and electrochemical properties depending on heating time. The additional oxidation step prior to reductive heating accelerates the final structure formation.

Figure 4. a) Electrochemical surface characterization of Pt(111) in 0.1 m HClO 4 measured with 50 mV s -1 in the electrochemical compartment without preparation and in the spoon after repeated annealing for 2 min in 4 % H 2 /Ar at 800 °C. b) Cyclic voltammogram of a welldefined Ir(111) single crystal in 0.05 m H 2 SO 4 at 50 mV s -1 during preparation period at 1900 °C: (···) initial, (---) after 20 heating periods, (··-) after 40 heating periods and (−) final CV. c) Voltammetric anodic scans of a poly crystalline Ir electrode, a Ni/Ir poly OL (overlayer) and a Ni/Irpoly NSA (nearsurface alloy) in 0.1 m KOH at a scan rate of 5 mV s -1 into the potential region of the oxygen evolution reaction (OER).

In article number 1800232 by Peter Strasser and co‐workers, a new multifunctional electrochemical (single) crystal test station enables cost‐effective, rapid thermal annealing and subsequent direct electrochemical characterization of any type of metallic or oxidic crystal surfaces for catalysis or support materials development. Inductive heating allows larger sample sizes and a transfer chamber features further analysis in separate devices.