Unique palladium‐gold hollow nanochains (PdAu HCs) with 1D architecture and an ultrathin Pd‐rich skin exhibit fantastic oxygen reduction reaction (ORR) enhancements due to their high conductivity, structural stability, and maximized atomic utilization. More importantly, such PdAu HCs possess periodic concave structures that boost ORR performance. These structures readily form high‐density high‐index facets, and fewer arc edges. Concave structures can deliver strong strain effects and surface charge accumulation is revealed by off‐axis electron holography. In addition, periodic concave structures can provide strong localized surface–plasmon coupling, which means that PdAu HCs have great potential as efficient surface‐enhanced Raman scattering (SERS) substrates. This study offers a novel and general approach for the design of complex noble metal‐based nanostructures as efficient ORR catalysts and SERS substrates.
A yolk-shell Fe/Fe 4 N@Pd/C (FFPC) nanocomposite is synthesized successfully by two facile steps: interfacial polymerization and annealing treatment. The concentration of Pd 2+ is the key factor for the density of Pd nanoparticles (Pd NPs) embedded in the carbon shells, which plays a role in the oxygen reduction reaction (ORR) and surface-enhanced Raman scattering (SERS) properties. The ORR and SERS performances of FFPC nanocomposites under different concentrations of PdCl 2 are investigated. The optimal ORR performance exhibits that onset potential and tafel slope can reach 0.937 V (vs reversible hydrogen electrode (RHE)) and 74 mV dec −1 , respectively, which is attributed to the synergistic effects of good electrical conductivity, large electrochemically active areas, and strong interfacial charge polarization. Off-axis electron holography reveals that interfacial charge polarization could facilitate the ORR of Pd NPs and defective carbon simultaneously and the shell with low density of Pd NPs is easier to form strong interfacial charge polarization. Moreover, FFPC-3 with maximum EF of 2.3 × 10 5 results from more hot-spots, local positive charge centers to attract rhodamine 6G molecules, and magnetic cores. This work not only offers a recyclable multifunctional nanocomposite with excellent performance, but also has instructional implications for interfacial engineering for electrocatalysts design.Multifunctional Nanocomposites www.advancedsciencenews.com
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