Is water oxidation catalyzed at the surface or within the bulk volume of solid oxide materials? This question is addressed for cobalt phosphate catalysts deposited on inert electrodes, namely crystallites of pakhomovskyite (Co3(PO4)2⋅8 H2O, Pak) and phosphate-containing Co oxide (CoCat). X-ray spectroscopy reveals that oxidizing potentials transform the crystalline Pak slowly (5-8 h) but completely into the amorphous CoCat. Electrochemical analysis supports high-TOF surface activity in Pak, whereas its amorphization results in dominating volume activity of the thereby formed CoCat material. In the directly electrodeposited CoCat, volume catalysis prevails, but not at very low levels of the amorphous material, implying high-TOF catalysis at surface sites. A complete picture of heterogeneous water oxidation requires insight in catalysis at the electrolyte-exposed "outer surface", within a hydrated, amorphous volume phase, and modes and kinetics of restructuring upon operation.

The requirements for beneficial materials restructuring into a higher performance oxygen evolution reaction (OER) electrocatalyst are still a largely open question. Here erythrite (Co3(AsO4)2·8H2O) is used as a Co‐based OER electrocatalyst to evaluate its catalytic properties during in situ restructuring into an amorphous Co‐based catalyst in four different electrolytes at pH 7. Using diffraction, microscopy, and spectroscopy, a strong effect in the restructuring behavior is observed depending of the anions in the electrolyte. Only carbonate electrolyte can activate the catalyst material, which is related to its slow restructuring process. While the catalyst turnover frequency (TOF) undesirably reduces by a factor of 28, the number of redox active sites continuously increases to a factor of 56, which results in an overall twofold increase in current of the restructured catalyst after 800 cycles. The activation is attributed to an adequate local order, a high Co oxidation state close to 3+, and a high number of redox‐active Co ions. These three requirements for beneficial restructuring provide new insights into the rational design of high‐performance OER catalysts by electrochemical restructuring.

Arsenate ions are incorporated in amorphous cobalt oxide catalysts at the periphery of the lattice or substituting cobalt ions.

A silanetriol and organoaluminum compounds react smoothly to give aluminosilcates of the type shown, which are soluble in organic solvents. Their cubeshaped Al4Si4O12 groups represent the smallest building blocks of zeolite A. Perhaps compounds of this type will be used in the near future in rational solid‐state syntheses under mild conditions. R1 = (2,6‐iPr2C6H3)(SiMe3)N, R2 = 1,4‐dioxane, THF, alkyl group.