The ability of plasmonic metal nanostructures (PMNs), such as silver and gold nanoparticles, to manipulate and concentrate electromagnetic fields at the nanoscale is the foundation for wide range of applications, including nanoscale optics, solar energy harvesting, and photocatalysis. However, there are inherent problems associated with plasmonic metals, such as high Ohmic losses and poorer compatibility with the conventional complementary metal−oxide−semiconductor (CMOS) microfabrication processes. These limitations inhibit the broader use of PMNs in practical applications. Herein, we report submicrometer cuprous oxide (Cu 2 O) cubic particles can exhibit strong electric and magnetic Mie resonances with extinction/scattering cross sections comparable to or slightly exceeding those of Ag particles. Using size-and shape-controlling particle synthesis techniques, optical spectroscopy, and finite-difference time-domain simulations, we show that the Mie resonance wavelengths are size-and shape-dependent and tunable in the visible to near-infrared regions. Therefore, submicrometer Cu 2 O cubic particles may potentially emerge as high-performance alternatives to PMNs. The strong electric and magnetic Mie-resonance-mediated nanoantenna attribute of the Cu 2 O cubic particles can be potentially used in a wide range of applications, including nanoscale optics, surface-enhanced Raman spectroscopy, surface-enhanced infrared absorption spectroscopy, photocatalysis, and photovoltaics.

Hybrid plasmonic nanostructures are built on plasmonic metalnanostructures surrounded by catalytic metals or metal oxides. Recent studies have shown that hybrid plasmonic nanocatalysts can concurrently utilize thermal energy and photon stimuli and exhibit high catalytic activity, selectivity, and stability that are not attainable in conventional purely thermally activated catalytic processes. The hybrid plasmonic photocatalytic approach has recently emerged as an attractive concept for the conversion of solar energy into chemical energy, the distributed synthesis of valuable chemicals such as ammonia with little to no requirement of external heating, and the development of coke‐resistant and selective catalytic processes. The field of hybrid plasmonic photocatalysis has grown tremendously in the last decade. In this review article, the advantages of visible‐light‐augmented hybrid plasmonic photocatalysis over conventional pure thermally activated heterogeneous catalysis are discussed. Fundamental insights are provided into photocatalytic mechanisms by which the photoexcited charge carriers (electrons and holes) are formed and transferred to adsorbates triggering chemical transformations on the surface of hybrid plasmonic nanocatalysts. Computational modeling used for predicting and understanding the photocatalytic activity and selectivity on hybrid plasmonic nanostructures is also reviewed. The review closes with a discussion of the current challenges, new opportunities, and future outlook for hybrid plasmonic photocatalysis.

Nanostructured metal oxides, such as Cu2O, CeO2, α-Fe2O3, and TiO2, can efficiently mediate photocatalysis for solar-to-chemical energy conversion and pollution remediation. In this contribution, we report a novel approach, dielectric Mie resonance-enhanced photocatalysis, to enhance the catalytic activity of metal oxide photocatalysts. Specifically, we demonstrate that Cu2O nanostructures exhibiting dielectric Mie resonances can exhibit up to an order of magnitude higher photocatalytic rate as compared with Cu2O nanostructures not exhibiting dielectric Mie resonances. Our finite-difference time-domain (FDTD) simulation and experimental results predict a volcano-type relationship between the photocatalytic rate and the size of Cu2O nanospheres and nanocubes. Using transient absorption measurements, we reveal that a coherent electronic process associated with dielectric Mie resonance-mediated charge carrier generation is dominant in Cu2O nanostructures that exhibit higher photocatalytic rates. Although we experimentally demonstrate dielectric Mie resonance-enhanced photocatalysis with only Cu2O nanoparticles here, based on our FDTD simulations, we anticipate the same can be achieved with other metal oxide photocatalysts, including CeO2, α-Fe2O3, and TiO2.

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Heterogeneous metal nanocatalysts have recently emerged as attractive catalysts for a variety of couplings (e.g., C−C, C−N, C−S, C−O, etc.). However, the characterization of the catalytic pathway remains challenging. By exploiting localized surface plasmon resonance (LSPR) of the catalytically relevant gold (Au) nanostructure, we show that UV−vis spectroscopy can be used to confirm the homogeneous catalytic pathway. Specifically, we have demonstrated that Au nanoparticles under C−C coupling conditions undergo substrate-induced leaching to form homogeneous Au catalytic species. The LSPR spectroscopic approach opens a new door to track stability of nanocatalysts and characterize the catalytic pathway in a range of coupling reactions.