Excavated polyhedral noble-metal materials that were built by the orderly assembly of ultrathin nanosheets have both large surface areas and well-defined facets, and therefore could be promising candidates for diverse important applications. In this work, excavated cubic Pt-Sn alloy nanocrystals (NCs) with {110} facets were constructed from twelve nanosheets by a simple co-reduction method with the assistance of the surface regulator polyvinylpyrrolidone. The specific surface area of the excavated cubic Pt-Sn NCs is comparable to that of commercial Pt black despite their larger particle size. The excavated cubic Pt-Sn NCs exhibited superior electrocatalytic activity in terms of both the specific area current density and the mass current density towards methanol oxidation.

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Engineering the surface electrochemistry at the atomic level can precisely and effectively manipulate the reactivity and durability of catalysts. Herein, a novel single‐atom fine‐tailoring strategy based on a highly hydrophilic Mo‐bifunctional promoter is proposed to greatly boost the hydrogen oxidation reaction (HOR) on Pt catalysts. The single‐atom Mo‐modified nanometer Pt anchored on porous N‐doped carbon (Mo‐Pt/NC) is developed via a pyrolysis–adsorption–reduction process. The designed Mo‐Pt/NC exhibits a remarkable mass‐specific kinetic current reaching 1584 mA mg−1Pt in 0.1 m KOH, which is nearly 11‐fold and fourfold higher than the activities of commercial Pt/C and Pt/NC counterparts respectively, and such extraordinary HOR behavior even exceeds those of documented Pt‐related catalysts. Electrochemical and spectroscopic studies indicate that hydrophilic Mo single‐atom sites can not only regulate the electronic microenvironment of Pt sites for attenuated H* adsorption, but they also serve as energetic H2O*‐adsorption promoters to jointly facilitate the HOR kinetics. Moreover, the anti‐CO poisoning capability of Mo‐Pt/NC is markedly enhanced by this Mo‐modified electronic effect. This work gives a significant guideline for the design of high‐performance HOR catalysts and other advanced catalysts.

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Excavated polyhedral noble-metal materials that were built by the orderly assembly of ultrathin nanosheets have both large surface areas and well-defined facets,and therefore could be promising candidates for diverse important applications.I nt his work, excavated cubic Pt-Sn alloyn anocrystals (NCs) with {110} facets were constructed from twelve nanosheets by as imple co-reduction method with the assistance of the surface regulator polyvinylpyrrolidone.T he specific surface area of the excavated cubic Pt-Sn NCs is comparable to that of commercial Pt black despite their larger particle size. The excavated cubic Pt-Sn NCs exhibited superior electrocatalytic activity in terms of both the specific area current density and the mass current density towards methanol oxidation.Noble-metal materials have been shown to play an irreplaceable role in an extensive range of applications. [1][2][3] Owing to their high cost and low abundance,h igh atomutilization efficiencies and superior activities are goals that we have pursued in the development of noble-metal materials for al ong time. [4][5][6][7] To fulfill these objects,r egulating the structures of noble-metal nanocrystals (NCs) with small sizes to obtain large specific areas and controlling the structures to expose high-energy facets to realize superior properties are two main approaches that have received substantial research interest over the past decades. [8][9][10] However,i ts eems that these two methods are incompatible with each other as it is difficult to synthesize small NCs with welldefined specific facets.From the structural point of view,NCs with an excavated polyhedral structure that are constructed by the orderly assembly of ultrathin nanosheets have large surface areas and specific exposed crystal facets. [5] Furthermore,t heir highly concave three-dimensional morphology could prevent agglomeration. Therefore,NCs with excavated polyhedral structures have an ideal morphology for various applications.Owing to the highly concave features and large surface area/volume ratios,excavated polyhedral NCs are thermodynamically not favored during crystal growth. Thus far,o nly very few examples of NCs with excavated polyhedral structures (e.g., excavated tetrahedra, excavated rhombic dodecahedra) have been described, [5,11,12] far less than the number of examples with convex and normal concave polyhedral morphologies.The exploration of such fascinating excavated nanostructures and the corresponding growth mechanisms should be of great fundamental interest. Apart from the surface and shape effects,a lloying and the alloy composition of noble-metal NCs also have ag reat influence on minimizing the usage of precious metals and achieving excellent activity owing to the synergistic effects between two metals. [13][14][15] However,the formation of excavated monometal NCs is already rather difficult, let alone the fabrication of bimetallic alloy NCs owing to the different reduction potentials,a tomic radii, and electronegativities of the alloy components. [16,17] Herein, ...

Icosahedra have small contact areas during packing, leading small icosahedral Pt nanoparticles to highly disperse on carbon nanotubes (CNT). The as-synthesized highly monodispersed Pt icosahedra on CNT exhibited superior catalytic activity and structural stability to their Pt nanocube counterparts on CNT towards methanol electro-oxidation.

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