High-throughput screening of carbon-supported single metal atom catalysts for oxygen reduction reaction

Carbon-supported transition metal single atoms are promising oxygen reduction reaction(ORR)electrocatalyst.Since there are many types of carbon supports and transition metals,the accurate prediction of the components with high activity through theoretical calculations can greatly save experimental time and costs.In this work,the ORR catalytic properties of 180 types single-atom catalysts(SACs)composed of the eight representative carbon-based substrates(graphdiyne,C_(2)N,C_(3)N_(4),phthalocyanine,C-coordination graphene,N-coordination graphene,covalent organic frameworks and metal-organic frameworks)and 3d,4d,and 5d transition metal elements are investigated by density functional theory(DFT).The adsorption free energy of OH^(*) is proved a universal descriptor capable of accurately prediction of the ORR catalytic activity.It is found that the oxygen reduction reaction overpotentials of all the researched SACs follow one volcano shape very well with the adsorption free energy of OH^(*).Phthalocyanine,N-coordination graphene and metal-organic frameworks stand out as the promising supports for single metal atom due to the relatively lower overpotentials.Notably,the Co-doped metal-organic frameworks,Ir-doped phthalocyanine,Co-doped N-coordination graphene,Co-doped graphdiyne and Rh-doped phthalocyanine show extremely low overpotentials comparable to that of Pt(111).The study provides a guideline for design and selection of carbon-supported SACs toward oxygen reduction reaction.

Surface plasmon polariton waveguides with subwavelength confinement

Surface plasmon polaritons（SPPs） are evanescent waves propagating along metal-dielectric interfaces, which provide an effective way to realize optical wave guiding with subwavelength confinement. Metallic nanostructures supporting SPPs,that is, plasmonic waveguides, are considered as required components to construct nanophotonic devices and circuits with a high degree of miniaturization and integration. In this paper, various types of plasmonic waveguides operating in the visible, infrared, and terahertz regions are reviewed, and the status of the research on their fundamentals, fabrications,and applications is provided as well. First, we discuss the mechanisms of SPPs beyond the diffraction limit, and their launching methods. Then, the characteristics of SPPs on various plasmonic waveguides are reviewed, including top-down and bottom-up fabricated types. Considering applications, certain prototypes of plasmonic devices and circuits constructed by plasmonic waveguides for bio/chemo sensing, router, and light modulation are demonstrated. Finally, a summary and future outlook of plasmonic waveguides are given.