The dependence on Pt catalysts has been a major issue of proton-exchange membrane (PEM) fuel cells. Strategies to maximize the Pt utilization in catalysts include two main approaches: to put Pt atoms only at the catalyst surface and to further enhance the surface-specific catalytic activity (SA) of Pt. Thus far there has been no practical design that combines these two features into one single catalyst. Here we report a combined computational and experimental study on the design and implementation of Pt-skin catalysts with significantly improved SA toward the oxygen reduction reaction (ORR). Through screening, using density functional theory (DFT) calculations, a Pt-skin structure on AuCu(111) substrate, consisting of 1.5 monolayers of Pt, is found to have an appropriately weakened oxygen affinity, in comparison to that on Pt(111), which would be ideal for ORR catalysis. Such a structure is then realized by substituting the Cu atoms in three surface layers of AuCu intermetallic nanoparticles (AuCu iNPs) with Pt. The resulting Pt-skinned catalyst (denoted as Pt(S)AuCu iNPs) has been characterized in depth using synchrotron XRD, XPS, HRTEM, and HAADF-STEM/EDX, such that the Pt-skin structure is unambiguously identified. The thickness of the Pt skin was determined to be less than two atomic layers. Finally the catalytic activity of Pt(S)AuCu iNPs toward the ORR was measured via rotating disk electrode (RDE) voltammetry through which it was established that the SA was more than 2 times that of a commercial Pt/C catalyst. Taking into account the ultralow Pt loading in Pt(S)AuCu iNPs, the mass-specific catalytic activity (MA) was determined to be 0.56 A/mg(Pt)@0.9 V, a value that is well beyond the DOE 2017 target for ORR catalysts (0.44 A/mg(Pt)@0.9 V). These findings provide a strategic design and a realizable approach to high-performance and Pt-efficient catalysts for fuel cells.

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In the present work, a one-pot method is employed to synthesize AuCu intermetallic nanoparticles (AuCu iNPs) supported on high-surface-area carbon. To avoid blocking the active sites of the AuCu iNPs for the subsequent study of electrocatalysis, no surfactant has been applied in the entire synthetic process. After refluxing in glycerol at 300 C, the ordered structure is formed in the carbon-supported AuCu iNPs, whose superlattice is evidently demonstrated by the X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterizations. Such intermetallic nanoparticles show very interesting electrochemical behaviors which have hitherto not been reported in the literature. In addition to the peculiar cyclic voltammetry (CV), the AuCu iNPs exhibit a superior catalytic activity, in comparison to that of ordinary Au nanoparticles, toward the oxygen reduction reaction (ORR) in alkaline media. The alteration in the surface electronic properties of Au, caused by the incorporation of Cu, has also been studied by X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations.

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MoS2/ZnIn2S4 composites with MoS2 anchored on the surface of ZnIn2S4 microspheres were synthesized by a two-step hydrothermal process. The obtained samples were characterized by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, ultraviolet-visible diffuse reflectance absorption spectroscopy, nitrogen adsorption-desorption measurements, photoluminescence spectroscopy, and photoelectrochemical tests. The influence of the loading of MoS2 on the photocatalytic H2 evolution activity was investigated using lactic acid as a sacrificial reagent. A H2 evolution rate of 343 μmol/h was achieved under visible light irradiation over the 1 wt% MoS2/ZnIn2S4 composite, corresponding to an apparent quantum efficiency of about 3.85% at 420 nm monochromatic light. The marked improvement of the photocatalytic H2 evolution activity compared with ZnIn2S4 can be ascribed to efficient transfer and separation of photogenerated charge carriers and facilitation of the photocatalytic H2 evolution reaction at the MoS2 active sites.

An intermetallic Pt2Si compound was prepared by magnetron sputtering, which exhibited higher HER activity than that of Pt in acidic solution.

Combined computational and experimental studies reveal a noble, non-d-band effect on Ag activation and electrocatalysis: upon coating Ag onto the even more inert Au surface, the catalytic activity toward the oxygen reduction reaction in alkaline media can be improved by about half an order of magnitude in comparison to the usual Ag surface.