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Structure engineering has proven to be an effective strategy for improving the catalytic performance and reducing the cost of ruthenium oxide‐based catalysts toward oxygen evolution reactions (OER). Herein, a polyhedron‐shaped yolk‐shell structure composed of zinc‐cobalt‐ruthenium ternary metal alloy oxide (ZnCo‐RuO2/C) is prepared, by taking advantage of the Kirkendall effect. The yolk‐shell frame and the ensembled metal oxide nanoparticles are 116.9 ± 25.9 nm and 3.1 ± 0.7 nm in diameter, respectively. The porous yolk‐shell structure of ZnCo‐RuO2/C exposes abundant active sites and facilitates mass transfer for OER. Theoretical calculations indicate that ZnCo‐RuO2 may break the linear scaling relationship for the OER intermediates and dramatically reduces the energy barrier of the potential determining step, which may be one of the factors that are responsible for the enhanced OER performance of ZnCo‐RuO2/C. In 1 m KOH aqueous electrolyte, ZnCo‐RuO2/C delivers an overpotential of only 180 mV at 10 mA cm−2 and a Tafel slope of 63 mV dec−1, superior to that of single metal‐doped, pristine and commercial RuO2. As an anode catalyst of zinc‐air batteries, ZnCo‐RuO2/C exhibits improved power density and durability relative to commercial RuO2, very promising for practical application.

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The crystal engineering of coordination polymers has aroused interest due to their structural versatility, unique properties and applications in different areas of science. The selection of appropriate ligands as building blocks is critical in order to afford a range of topologies. Alkali metal cations are known for their mainly ionic chemistry in aqueous media. Their coordination number varies depending on the size of the binding partners, and on the electrostatic interaction between the ligands and the metal ions. The two-dimensional coordination polymer poly[tetra-μ-aqua-[μ4-4,4'-(diazenediyl)bis(5-oxo-1H-1,2,4-triazolido)]disodium(I)], [Na2(C4H2N8O2)(H2O)4]n, (I), was synthesized from 4-amino-1H-1,2,4-triazol-5(4H)-one (ATO) and its single-crystal structure determined. The mid-point of the imino N=N bond of the 4,4'-(diazenediyl)bis(5-oxo-1H-1,2,4-triazolide) (ZTO(2-)) ligand is located on an inversion centre. The asymmetric unit consists of one Na(+) cation, half a bridging ZTO(2-) ligand and two bridging water ligands. Each Na(+) cation is coordinated in a trigonal antiprismatic fashion by six O atoms, i.e. two from two ZTO(2-) ligands and the remaining four from bridging water ligands. The Na(+) cation is located near a glide plane, thus the two bridging O atoms from the two coordinating ZTO(2-) ligands are on adjacent apices of the trigonal antiprism, rather than being in an anti configuration. All water and ZTO(2-) ligands act as bridging ligands between metal centres. Each Na(+) metal centre is bridged to a neigbouring Na(+) cation by two water molecules to give a one-dimensional [Na(H2O)2]n chain. The organic ZTO(2-) ligand, an O atom of which also bridges the same pair of Na(+) cations, then crosslinks these [Na(H2O)2]n chains to form two-dimensional sheets. The two-dimensional sheets are further connected by intermolecular hydrogen bonds, giving rise to a stabile hydrogen-bonded network.