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The rational control of the electrochemical properties of polyoxovanadate-alkoxide clusters is dependent on understanding the influence of various synthetic modifications on the overall redox processes of these systems. In this work, the electronic consequences of ligand substitution at the heteroion in a heterometal-functionalized cluster was examined. The redox properties of [V5 O6 (OCH3 )12 FeCl] (1-[V5 FeCl]) and [V5 O6 (OCH3 )12 Fe]X (2-[V5 Fe]X; X=ClO4 , OTf) were compared in order to assess the effects of changing the coordination environment around the iron center on the electrochemical properties of the cluster. Coordination of a chloride anion to iron leads to an anodic shift in redox events. Theoretical modelling of the electronic structure of these heterometal-functionalized clusters reveals that differences in the redox profiles of 1-[V5 FeCl] and 2-[V5 Fe]X arise from changes in the number of ligands surrounding the iron center (e.g., 6-coordinate vs. 5-coordinate). Specifically, binding of the chloride to the sixth coordination site appears to change the orbital interaction between the iron and the delocalized electronic structure of the mixed-valent polyoxovanadate core. Tuning the heterometal coordination environment can therefore be used to modulate the redox properties of the whole cluster.

Defect engineering is a key chemical tool to modulate the electronic structure and reactivity of nanostructured catalysts. Here, it is reported how targeted introduction of defect sites in a 2D palladium metallene nanostructure results in a highly active catalyst for the alkaline oxygen reduction reaction (ORR). A defect‐rich WOx and MoOx modified Pd metallene (denoted: D‐Pd M) is synthesized by a facile and scalable approach. Detailed structural analyses reveal the presence of three distinct atomic‐level defects, that are pores, concave surfaces, and surface‐anchored individual WOx and MoOx sites. Mechanistic studies reveal that these defects result in excellent catalytic ORR activity (half‐wave potential 0.93 V vs. RHE, mass activity 1.3 A mgPd−1 at 0.9 V vs. RHE), outperforming the commercial references Pt/C and Pd/C by factors of ≈7 and ≈4, respectively. The practical usage of the compound is demonstrated by integration into a custom‐built Zn‐air battery. At low D‐Pd M loading (26 µgPd cm−2), the system achieves high specific capacity (809 mAh gZn−1) and shows excellent discharge potential stability. This study therefore provides a blueprint for the molecular design of defect sites in 2D metallene nanostructures for advanced energy technology applications. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction is a promising approach to remove harmful nitrate and produce ammonia in aqueous media. Here, we demonstrate how 3D printed polymer electrodes can be electroless plated with a bimetallic NiCu alloy film suitable for sustained nitrate‐to‐ammonia reduction. Characterization by powder X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning/transmission electron microscopy and energy‐dispersive X‐ray spectroscopy indicate that the electrode has a two‐layer structure consisting of polymer/ coating layer of metal alloys. The composite electrode shows high‐performance in the nitrate‐to‐ammonia electroreduction, giving NH3 Faradaic efficiencies of up to 83 % and NH3 yield rates up to 860 μg/(h cm2) at −0.38 V vs. RHE. We show that the electrode can easily be integrated into a Zn‐nitrate battery, giving a power density of 3.8 mW cm−2 with continuous NH3 production. The system combines three productive outputs, that is removal of nitrate pollutants, synthesis of valuable ammonia and generation of "green" electricity. [ABSTRACT FROM AUTHOR]

Nature uses reactive components embedded in biological membranes to perform light‐driven photosynthesis. Here, a model artificial photosynthetic system for light‐driven hydrogen (H2) evolution is reported. The system is based on liposomes where amphiphilic ruthenium trisbipyridine based photosensitizer (RuC9) and the H2 evolution reaction (HER) catalyst [Mo3S13]2− are embedded in biomimetic phospholipid membranes. When DMPC was used as the main lipid of these light‐active liposomes, increased catalytic activity (TONCAT ~200) was observed compared to purely aqueous conditions. Although all tested lipid matrixes, including DMPC, DOPG, DPPC and DOPG liposomes provided similar liposomal structures according to TEM analysis, only DMPC yielded high H2 amounts. In situ scanning electrochemical microscopy (SECM) measurements using Pd microsensors revealed an induction period of around 26 minutes prior to H2 evolution, indicating an activation mechanism which might be induced by the fluid‐gel phase transition of DMPC at room temperature. Stern‐Volmer‐type quenching studies revealed that electron transfer dynamics from the excited state photosensitizer are most efficient in the DMPC lipid environment giving insight for design of artificial photosynthetic systems using lipid bilayer membranes. [ABSTRACT FROM AUTHOR]