Bimetallic nanostructures: combining plasmonic and catalytic metals for photocatalysis

Abstract

Light has emerged as a promising new reagent in chemical reactions, especially in enhancing the performance of metal nanoparticle catalysts. Certain metal nanoparticles support localized surface plasmon resonances (LSPRs) which convert incident light to strong electromagnetic fields, hot carriers, or heat for directing and improving chemical reactions. By combining plasmonically active metals with traditionally catalytic metals, bimetallic nanostructures promote simultaneous light conversion and strong molecular adsorption, expanding the library of light-controlled reactions. In this review, we cover three bimetallic geometries: antenna-reactor, core-shell, and alloyed nanoparticle systems. Each geometry hosts its own set of intermetallic interactions which can affect the photocatalytic response. While antenna-reactor systems rely exclusively on optical coupling between the plasmonic and catalytic metal to enhance reactivity, core-shell and alloy architectures introduce electronic interactions in addition to optical effects. These electronic interactions usually dampen the plasmonic response but also offer the potential for enhanced reactivity and product specificity. We review both state-of-the-art bimetallic photocatalysts as well as emerging research opportunities, including leveraging quantum effects, new computational methods to understand and predict photocatalysts, and atomic-scale architecting of materials.

A Library of Late Transition Metal Alloy Dielectric Functions for Nanophotonic Applications

“…[ 2–10 ] Some of these materials have already found applications, for example in plasmonic hydrogen sensors, [ 11,12 ] or are suggested for the use in plasmon‐mediated catalysis. [ 13 ]…”

Versatile and robust synthesis process for the fine control of the chemical composition and core-crystallinity of spherical core–shell Au@Ag nanoparticles

“…Bimetallic Au@Ag core-shell nanoparticles have received extensive interest for many years due to the possibility of tuning their properties through the size of the core, the thickness of the shell and the structural coupling between the core and the shell. In this way, it becomes possible to modify and control the plasmon resonances for surface-enhanced Raman scattering (SERS) applications, catalysis, and chemical sensing [13,[17][18][19][20][21][22]. The synthesis of alloys or core-shells is facilitated for gold and silver by their similar crystal structure (fcc) and lattice constants (a = 0.408 nm for Au and 0.409 nm for Ag) [19].…”

“…It is based on the use of oleylamine to solubilize and reduce the silver metallic precursor for the shell under annealing for a controlled time at the surface of the Au seed, which is itself synthesized by different pathways in an organic medium. The resulting Au@Ag core-shell NPs are of controlled crystallinity and composition; factors that play a fundamental role in their optical and catalytic properties [13,30,31]. Furthermore, they have a narrow size distribution that facilitates their 3D assembly after deposition on a solid substrate for further applications as new SERS platforms with tunable optical properties [32].…”

Nanoscale structural characterization of plasmon-driven reactions

“…The catalytic properties of noble metal nanostructures can be broadened by coupling noble with catalytic metals such as palladium (Pd), ruthenium (Ru) or platinum (Pt) in one bimetallic construct [63]. Such bimetallic nanostructures catalyze a broad range of chemical reactions.…”