Hydrogen production using water electrolysers equipped with an anion exchange membrane, a pure water feed and cheap components (catalysts and bipolar plates) can challenge proton exchange membrane electrolysis systems as the state of the art.

Seawater electrolysis faces fundamental chemical challenges, such as the suppression of highly detrimental halogen chemistries, which has to be ensured by selective catalyst and suitable operating conditions. In the present study, nanostructured NiFe‐layered double hydroxide and Pt nanoparticles are selected as catalysts for the anode and cathode, respectively. The seawater electrolyzer is tested successfully for 100 h at maximum current densities of 200 mA cm−2 at 1.6 V employing surrogate sea water and compared to fresh water feeds. Different membrane studies are carried out to reveal the cause of the current density drop. During long‐term dynamic tests, under simulated day‐night cycles, an unusual cell power performance recovery effect is uncovered, which is subsequently harnessed in a long‐term diurnal day‐night cycle test. The natural day‐night cycles of the electrolyzer input power can be conceived as a reversible catalyst materials recovery treatment of the device when using photovoltaic electricity sources. To understand the origin of this reversible recovery on a molecular materials level, in situ extended X‐ray absorption fine structure and X‐ray near‐edge region spectra are applied.

Water oxidation is pivotal in biological photosynthesis, where it is catalyzed by a protein-bound metal complex with a Mn4Ca-oxide core; related synthetic catalysts may become key components in non-fossil fuel technologies.

The emergence of disordered metal oxides as electrocatalysts for the oxygen evolution reaction and reports of amorphization of crystalline materials during electrocatalysis reveal a need for robust structural models for this class of materials. Here we apply a combination of low-temperature X-ray absorption spectroscopy and time-resolved in situ X-ray absorption spectroelectrochemistry to analyze the structure and electrochemical properties of a series of disordered iron-cobalt oxides. We identify a composition-dependent distribution of di-μ-oxo bridged cobalt–cobalt, di-μ-oxo bridged cobalt–iron and corner-sharing cobalt structural motifs in the composition series. Comparison of the structural model with (spectro)electrochemical data reveals relationships across the composition series that enable unprecedented assignment of voltammetric redox processes to specific structural motifs. We confirm that oxygen evolution occurs at two distinct reaction sites, di-μ-oxo bridged cobalt–cobalt and di-μ-oxo bridged iron–cobalt sites, and identify direct and indirect modes-of-action for iron ions in the mixed-metal compositions.

A unique class of bifunctional robust materials was discovered which not only facilitates both the electrocatalytic oxidation and reduction of water to oxygen and hydrogen but also combines outstanding performance and energetic efficiency with remarkable long-term stability.

The mechanistically distinct and synergistic role of phosphite anions in hydrogen evolution and nickel cations in oxygen evolution have been uncovered for active and durable overall water splitting catalysis in nickel phosphite.

Iron is observed to induce geometric distortions in oxidized nickel oxyhydroxide that activate the material for the oxygen evolution reaction.

NiFe oxyhydroxides are prime candidates for efficient alkaline water oxidation; their redox chemistry is tracked by X-ray spectroscopy.