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Abstract: In terms of promising candidates for high‐performance fuel cells and water splitting electrocatalysts, two‐dimensional (2D) materials refer to a class of materials with high electrical conductivity along 2D conducting channels and possessing abundant active sites in the form of surface atoms and edge sites. Herein, we report an ammonia‐modulated method for the synthesis of nanosized bimetallic ZnCo‐ZIF, and owing to quantum effects, the nanosized ZnCo‐ZIF can be transformed into novel 2D nanosheet arrays, which can be used as a bifunctional electrocatalyst. The size of the ZnCo‐ZIF crystals can be controlled to less than 10 nm by increasing the ammonia amount. The products from the nanosized particles through calcination have a distinct structure from the microsized nanoparticles owing to quantum effects and appear to be well‐aligned 2D mono‐crystalline Co3O4‐embedded nitrogen‐doped porous carbon nanosheet arrays (2D‐MCo3O4‐NCNAs). These novel 2D nanosheet arrays lead to large active surface areas, enhanced mass/charge transport capability, numerous active sites, and strong structure stability. When used as bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), the 2D‐MCo3O4‐NCNAs exhibit superior ORR activity as well as efficient OER activity in alkaline electrolyte, in comparison to the state‐of‐the‐art precious metal catalysts. [ABSTRACT FROM AUTHOR]

Abstract: Highly active, durable, and cost‐effective electrocatalysts for water oxidation are at the center of renewable energy technologies. However, the development of water oxidation catalysts with high activity at low cost remains a great challenge. Herein, an in situ antisolvent approach is reported for synthesizing ultrathin Co–Ni layered double hydroxide (CoNi‐LDH) nanosheets wrapped on hollow Co3O4 nanoparticle‐embedded nitrogen‐doped carbon (HCo3O4‐NC) as a high‐performance catalyst for the oxygen evolution reaction (OER). Although HCo3O4‐NC or NiCo‐LDH alone has little OER activity, their hybrid exhibits low overpotential and Tafel slope as well as high stability, due to the synergistic effect of Co3O4 and LDH. Furthermore, the hydrangea‐like HCo3O4‐NC@NiCo‐LDH core@shell composite exhibits higher catalytic activity and stability than commercial IrO2, which makes it a high‐performance nonprecious‐metal‐based catalyst for OER. [ABSTRACT FROM AUTHOR]

Mixed-metal sulfide Zn1− xMn xS nanorod-assembled hierarchical hollow spheres were synthesized by a template-free solvothermal process based on Ostwald ripening. In the reaction system, glycerol plays a key role in the formation of Zn xMn1− xS hierarchical hollow structures by a quasi-microemulsion-template mechanism. When applied as capacitor electrode material, the hierarchical Zn1− xMn xS hollow spheres show excellent electrochemical performance. Specifically, Zn0.25Mn0.75S hollow spheres can deliver a high specific capacitance of 664 F g−1 at a current rate of 1 A g−1, which is almost five times of that of MnS under the same conditions and higher than those of previously reported single Mn-based compounds. [ABSTRACT FROM AUTHOR]