In a green energy economy, electrocatalysis is essential for chemical energy conversion and to produce value added chemicals from regenerative resources. To be widely applicable, an electrocatalyst should comprise the Earth's crust's most abundant elements. The most abundant 3d metal, iron, with its multiple accessible redox states has been manifold applied in chemocatalytic processes. However, due to the low conductivity of Fe^IIIO_xH_y phases, its applicability for targeted electrocatalytic oxidation reactions such as water oxidation is still limited. Herein, it is shown that iron incorporated in conductive intermetallic iron silicide (FeSi) can be employed to meet this challenge. In contrast to silicon‐poor iron–silicon alloys, intermetallic FeSi possesses an ordered structure with a peculiar bonding situation including covalent and ionic contributions together with conducting electrons. Using in situ X‐ray absorption and Raman spectroscopy, it could be demonstrated that, under the applied corrosive alkaline conditions, the FeSi partly forms a unique, oxidic iron(III) phase consisting of edge and corner sharing [FeO₆] octahedra together with oxidized silicon species. This phase is capable of driving the oxyge evolution reaction (OER) at high efficiency under ambient and industrially relevant conditions (500 mA cm⁻² at 1.50 ± 0.025 V_RHE and 65 °C) and to selectively oxygenate 5‐hydroxymethylfurfural (HMF).

Electrochemical water splitting remains a frontier research topic in the quest to develop artificial photosynthetic systems by using noble metal‐free and sustainable catalysts. Herein, a highly crystalline CuSe has been employed as active electrodes for overall water splitting (OWS) in alkaline media. The pure‐phase klockmannite CuSe deposited on highly conducting nickel foam (NF) electrodes by electrophoretic deposition (EPD) displayed an overpotential of merely 297 mV for the reaction of oxygen evolution (OER) at a current density of 10 mA cm⁻² whereas an overpotential of 162 mV was attained for the hydrogen evolution reaction (HER) at the same current density, superseding the Cu‐based as well as the state‐of‐the‐art RuO₂ and IrO₂ catalysts. The bifunctional behavior of the catalyst has successfully been utilized to fabricate an overall water‐splitting device, which exhibits a low cell voltage (1.68 V) with long‐term stability. Post‐catalytic analyses of the catalyst by ex‐situ microscopic, spectroscopic, and analytical methods confirm that under both OER and HER conditions, the crystalline and conductive CuSe behaves as an electro(pre)catalyst forming a highly reactive in situ crystalline Cu(OH)₂ overlayer (electro(post)catalyst), which facilitates oxygen (O₂) evolution, and an amorphous Cu(OH)₂/CuO_x active surface for hydrogen (H₂) evolution. The present study demonstrates a distinct approach to produce highly active copper‐based catalysts starting from copper chalcogenides and could be used as a basis to enhance the performance in durable bifunctional overall water splitting.

Reinvestigation of the reaction of Li₇Ge₁₂ with benzophenone in tetrahydrofuran solution affords the metastable crystalline germanium allotrope allo-Ge, which transforms into another allotrope, 4H-Ge, upon annealing at temperatures between 150 and 300 °C. When annealing 4H-Ge above 400 °C the ground state modification α-Ge is obtained. The crystal structure of 4H-Ge was refined from powder X-ray diffraction data (space group P6₃/mmc (no. 194), a = 3.99019(4) and c = 13.1070(2) Å, Z = 8) and the sequence of phase transitions from allo-Ge to α-Ge was monitored by temperature-dependent powder X-ray diffraction experiments. Electrical resistivity measurements and quantum-mechanical calculations show that 4H-Ge is a semiconductor, which is in contrast to previous theoretical predictions. The Raman spectrum of 4H-Ge displays three bands at 299, 291, and 245 cm⁻¹ which are assigned to E_1g, E_2g and A_1g modes, respectively, and relate to the optic mode in α-Ge.