The commercialization of proton exchange membrane fuel cells (PEMFCs) relies on highly active and stable electrocatalysts for oxygen reduction reaction (ORR) in acid media. The most successful catalysts for this reaction are nanostructured Pt-alloyw ith aP t-skin. The synthesis of ultrasmall and ordered L1 0 -PtCo nanoparticle ORR catalysts further doped with af ew percent of metals (W,G a, Zn) is reported. Compared to commercial Pt/C catalyst, the L1 0 -W-PtCo/C catalyst shows significant improvement in both initial activity and high-temperature stability.T he L1 0 -W-PtCo/C catalyst achieves high activity and stability in the PEMFC after 50 000 voltage cycles at 80 8 8C, which is superior to the DOE 2020 targets.E XAFS analysis and density functional theory calculations reveal that Wd oping not only stabilizes the ordered intermetallic structure,but also tunes the Pt-Pt distances in such away to optimize the binding energy between Pt and O intermediates on the surface.

PtM alloy catalysts (e.g., PtFe, PtCo), especially in an intermetallic L1 0 structure, have attracted considerable interests due to their respectable activity and stability for oxygen reduction This article is protected by copyright. All rights reserved.3 reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). However, metal-catalyzed formation of •OH from H 2 O 2 (i.e., Fenton reaction) by Fe-or Co-containing catalysts causes severe degradation of PEM/catalyst layers, hindering the prospects in commercial applications. Zinc (Zn) is known as an antioxidant in Fenton reaction, but rarely alloyed with Pt owing to its relatively negative redox potential. Here, we synthesized sub-4 nm intermetallic L1 0 -PtZn nanoparticles (NPs) as high-performance PEMFC cathode catalysts. In PEMFC tests, the L1 0 -PtZn cathode achieves outstanding activity (0.52 A mg Pt -1 at 0.9 V iR-free , and peak power density of 2.00 W cm -2 ) and stabilityonly 16.6 % loss in mass activity after 30,000 voltage cycles), exceeding the U.S. DOE 2020 targets and most of the reported ORR catalysts. Density function theory (DFT) calculations reveal that biaxial strains developed upon the disorder-order (A1-L1 0 ) transition of PtZn NPs would modulate the surface Pt-Pt distances and optimize Pt-O binding for ORR activity enhancement, while the increased vacancy formation energy of Zn atoms in ordered structure accounts for the improved stability. PtZn slabs. (f) Correlations between the formation energy and vacancy formation energy of M in various L1 0 -PtM systems. TOC Structurally ordered L1 0 -PtZn nanoparticles are developed as catalysts for oxygen reduction in proton exchange membrane fuel cells (PEMFCs). The L1 0 -PtZn catalyst with a "Pt-skin" achieves outstanding activity, power density, and stability in a PEMFC. The extraordinary fuel cell performance of L1 0 -PtZn/Pt is ascribed to the optimized biaxial strains, the Fenton reaction resistance, and the increased vacancy formation energy of Zn.

The present study originally created a methodology for immobilizing polymeric nanoparticles on graphene oxide (GO) by chemical bonds, aiming at chiral functionalization of GO and simultaneously improving the dispersibility of polymer nanoparticles. To prepare the novel GO hybrids, GO was first prepared and alkynylated to form an actual comonomer (M GO ), in the presence of which acetylenic monomer (M 1 ) underwent emulsion polymerization in aqueous media with sodium dodecyl sulfate as emulsifier and (nbd)Rh + B − (C 6 H 5 ) 4 as catalyst. SEM and HRTEM images ascertained the formation of polymeric nanoparticles immobilized on GO (NP poly1 /GO). CD and UV−vis absorption spectra demonstrated the optical activity of NP poly1 /GO, originated from the chiral helical conformations adopted by the polymer chains constructing the nanoparticles. FT-IR, Raman, XPS, XRD, and TGA techniques were also utilized to characterize the GO hybrids. The as-obtained NP poly1 /GO was further used as a chiral additive to perform enantioselective crystallization of L-alanine from racemic alanine. L-Alanine was preferentially induced to crystallize rod-like crystals, according to SEM, CD, and XRD characterizations. The present study provides a versatile platform for preparing GO-derived functional materials, particularly novel chiral materials.

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Ultrathin and defect-rich Pd2Sn intermetallic nanosheets with unique Pd–Sn ordering are developed and display much enhanced activity and stability towards oxygen reduction in an alkaline medium.