Precise control over the size, shape, composition, structure, and crystal phase of random alloy and intermetallic nanocrystals has been intensively explored in technologically important applications in recent years. Different from the monometallic nanocrystals and other types of structural nanocrystals such as core−shell and heterostructured nanocrystals, well-defined multimetallic random alloy and intermetallic nanocrystals exhibit unique and intriguing physicochemical properties, serving as ideal models for benefiting the structure-to-property studies. As such, random alloy and intermetallic nanocrystals have attracted extensive attention and interest in scientific research and shown huge potential in various fields. In this review, we focus specifically on summarizing the synthetic principles and strategies developed to form random alloy and intermetallic nanocrystals with enhanced performance. Some representative examples are purposely selected for emphasizing basic concepts and mechanistic understanding. We then highlight the fascinating properties and widespread applications of random alloy and intermetallic nanocrystals in electrocatalysis, heterogeneous catalysis, optical and photocatalysis, as well as magnetism and conclude the review by addressing the prospects and current challenges for the controlled synthesis of random alloy and intermetallic nanocrystals.

Ni–Co sulfide nanowires synthesized by a two-step hydrothermal method show good performance when used as the positive electrode for asymmetric supercapacitors.

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We report a quantitative understanding of the reduction kinetics responsible for the formation of Pd-Pt bimetallic nanocrystals with two distinctive structures. The syntheses involve the use of KBr to manipulate the reaction kinetics by influencing the redox potentials of metal precursor ions via ligand exchange. In the absence of KBr, the ratio between the initial reduction rates of PdCl4(2-) and PtCl4(2-) was about 10.0, leading to the formation of Pd@Pt octahedra with a core-shell structure. In the presence of 63 mM KBr, the products became Pd-Pt alloy nanocrystals. In this case, the ratio between the initial reduction rates of the two precursors dropped to 2.4 because of ligand exchange and, thus, the formation of PdBr4(2-) and PtBr4(2-). The alloy nanocrystals took a cubic shape owing to the selective capping effect of Br(-) ions toward the {100} facets. Relative to the alloy nanocubes, the Pd@Pt core-shell octahedra showed substantial enhancement in both catalytic activity and durability toward the oxygen reduction reaction (ORR). Specifically, the specific (1.51 mA cm(-2)) and mass (1.05 A mg(-1) Pt) activities of the core-shell octahedra were enhanced by about four- and three-fold relative to the alloy nanocubes (0.39 mA cm(-2) and 0.34 A mg(-1) Pt, respectively). Even after 20000 cycles of accelerated durability test, the core-shell octahedra still exhibited a mass activity of 0.68 A mg(-1) Pt, twice that of a pristine commercial Pt/C catalyst.