Gold Nanobipyramids: An Emerging and Versatile Type of Plasmonic Nanoparticles

Abstract

Conspectus Gold nanobipyramids (Au NBPs) and gold nanorods (Au NRs) are two types of elongated plasmonic nanoparticles with their longitudinal dipolar plasmon wavelengths synthetically tunable from the visible region to the near-infrared region. Both have highly polarization-dependent absorption and scattering cross sections because of their anisotropic geometries. In terms of their differences, each Au NBP has five equally angularly separated twinning planes that are aligned parallel to the length direction, while the most common Au NRs are single-crystalline. As a result, Au NBPs possess two sharp end tips, while Au NRs have rounded or flat ends, resulting in very different plasmonic properties. In general, Au NBPs exhibit larger local electric field enhancements, larger optical cross sections, narrower line widths, better shape and size uniformity, and higher refractive index sensitivity than Au NRs. With the recent development of reliable methods for the growth of Au NBPs with high purity and uniformity, Au NBPs have been attracting much interest for the investigation of their intriguing plasmonic properties and applications. In this Account, we provide a concise introduction to Au NBPs, including their fascinating plasmonic properties, wet-chemistry growth methods, plasmonic applications, and structure-directing function. The synthesis of uniform Au NBPs with variable sizes is of vital importance to control their plasmonic properties. In the synthesis part, we summarize the recent developments on the synthesis of Au NBPs, with a focus on the role of seeds in the seed-mediated growth of pentatwinned Au NBPs and methods to improve their number purity. The excellent plasmonic properties of Au NBPs make them promising candidates for numerous applications. To further explore the largely improved functionalities of Au NBPs, different types of Au-NBP-based hybrid nanostructures have been prepared. They exhibit synergistic interactions between Au NBPs and the other components. We highlight the widespread plasmonic applications of Au NBPs and Au-NBP-based hybrid nanostructures in the fields of spectroscopy, photocatalysis, sensing, switching, and biomedical technologies. We next turn to the structure-directing function of Au NBPs to demonstrate the Au-NBP-directed growth of metal nanostructures and their applications. The structure-directing function is enabled by the unique pentatwinned crystalline structure of Au NBPs. Finally, we conclude with remarks on the future perspectives and research directions on Au NBPs as well as the remaining challenges. We hope that this Account will act as a platform to offer fascinating opportunities and stimulate fast-growing research on the various aspects of Au NBPs.

Nonspherical Metal‐Based Nanoarchitectures: Synthesis and Impact of Size, Shape, and Composition on Their Biological Activity

“…The citrate‐capped Au seeds exhibit penta‐twinned structures which produce nanobipyramids during the growth process. [ 29,173 ] A seed‐mediated approach is also utilized for synthesizing CuS nanoprisms, using oleylamine as the capping agent that activates sulfur atoms by producing oleylammonium hydrosulfide. The latter reacts with Cu (II) ions to generate disk‐shaped CuS seeds.…”

Platinum‐Based Electrocatalysts for Direct Alcohol Fuel Cells: Enhanced Performances toward Alcohol Oxidation Reactions

“…LSPR, the collective oscillation of free electrons confined at the nanoscale, has been widely studied in various applications, such as biosensors, photocatalysis, photodetectors and solar cells. [163] Recently, numerous investigations focus on applying LSPR in electrocatalysis by combing plasmonic metals with Pt-based nanostructures. [164][165][166][167][168] Under the assistance of solar light, the photoexcited hot carriers (h + -e À ) can be transfer to the external circuit or take part in the oxidation reaction.…”

“…Herein, we focused on the localized surface plasmon resonance (LSPR) assisted electrocatalysis to AOR that has attracted great attention in very recent years. LSPR, the collective oscillation of free electrons confined at the nanoscale, has been widely studied in various applications, such as biosensors, photocatalysis, photodetectors and solar cells [163] . Recently, numerous investigations focus on applying LSPR in electrocatalysis by combing plasmonic metals with Pt‐based nanostructures [164–168] .…”

Individual Plasmonic Nanoprobes for Biosensing and Bioimaging: Recent Advances and Perspectives

“…[ 38–80 ] To satisfy the different requirements for the DFM technique, a variety of nanoprobes, including gold nanoparticles (AuNPs), silver nanoparticles (AgNPs), copper nanoparticles (CuNPs), and aluminum (Al)‐based nanostructures have been synthesized. [ 81–85 ] The most commonly employed nanoprobes are AuNPs and AgNPs because of their excellent ability to support plasmons. With the assistance of suitable PNPs, which convert chemical or physical stimuli in their local environment to Rayleigh scattering light signals in a highly efficient way, DFM techniques have been widely applied in studying dynamic systems with rapid kinetics and quantification of biomolecules.…”