Two-dimensional (2D) metals are an emerging class of nanostructures that have attracted enormous research interest due to their unusual electronic and thermal transport properties. Adding mesopores in the plane of ultrathin 2D metals is the next big step in manipulating these structures because increasing their surface area improves the utilization of the material and the availability of active sites. Here, we report a novel synthetic strategy to prepare an unprecedented type of 2D mesoporous metallic iridium (Ir) nanosheet. Mesoporous Ir nanosheets can be synthesized with close-packed assemblies of diblock copolymer (poly-(ethylene oxide)- b-polystyrene, PEO- b-PS) micelles aligned in the 2D plane of the nanosheets. This novel synthetic route opens a new dimension of control in the synthesis of 2D metals, enabling new kinds of mesoporous architectures with abundant catalytically active sites. Because of their unique structural features, the mesoporous metallic Ir nanosheets exhibit a high electrocatalytic activity toward the oxygen evolution reaction (OER) in acidic solution as compared to commercially available catalysts.

The self-assembly of two-dimensional (2D) nanostructures into one-dimensional (1D) nanoarchitectures may result in materials which combine the unique physicochemical properties of 2D nanostructures with the excellent charge transport properties of 1D architectures. Herein, we report the self-stacking of 2D nickel−cobalt (Ni−Co) phosphate nanoplates into 1D chainlike architectures with the assistance of metal glycerates as self-templates. This unique selfassembly process is driven by the adsorbed ethyl glycerate on the surface of the individual nanoplates, which promotes the subsequent growth of the new nanoplate on top of the previously formed nanoplate, thereby leading to the self-stacking of these nanoplates along the vertical direction. The flexibility of the proposed method is also highlighted by the feasible preparation of nickel phosphate with the same self-assembled structure. When tested as a catalyst for oxygen evolution reaction (OER) in an alkaline medium, the bimetallic Ni−Co phosphate (derived from Ni-Co-TEP) with the nanoplate-assembled chainlike structure displays much lower overpotential (η 10 = 310 mV) and Tafel slope (68 mV dec −1 ) than its pristine counterparts. The enhanced OER activity of this bimetallic catalyst may be attributed to (i) the highly interconnected structure and the bimetallic composition which promote improved charge transport; (ii) the porous chainlike structure which provides increased number of active sites, facilitates easier electrolyte infiltration, and promotes good electrical contact with the electrolyte, and (iii) the presence of Ni 3+ and Co 3+ active sites (nickel−cobalt (oxy)hydroxides) which can promote the chemisorption of OH − and facilitate electron transfer from the OH − to the surface Ni/Co sites during OER.

Generating high surface area mesoporous transition metal boride is challenging but interesting because incorporation of boron atoms can generate lattice distortion to form amorphous metal boride which has unique properties in catalysis.

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