Mesoporous gold (Au) films with tunable pores are expected to provide fascinating optical properties stimulated by the mesospaces, but they have not been realized yet because of the difficulty of controlling the Au crystal growth. Here, we report a reliable soft-templating method to fabricate mesoporous Au films using stable micelles of diblock copolymers, with electrochemical deposition advantageous for precise control of Au crystal growth. Strong field enhancement takes place around the center of the uniform mesopores as well as on the walls between the pores, leading to the enhanced light scattering as well as surface-enhanced Raman scattering (SERS), which is understandable, for example, from Babinet principles applied for the reverse system of nanoparticle ensembles.

Highly efficient utilization of solar light with an excellent reduction capacity is achieved for plasmonic Fe@C nanostructures. By carbon layer coating, the optimized catalyst exhibits enhanced selectivity and stability applied to the solar-driven reduction of CO2 into CO. The surface-plasmon effect of iron particles is proposed to excite CO2 molecules, and thereby facilitates the final reaction activity.

Photocatalytic reduction of carbon dioxide (CO) is attractive for the production of valuable fuels and mitigating the influence of greenhouse gas emission. However, the extreme inertness of CO and the sluggish kinetics of photoexcited charge carrier transfer process greatly limit the conversion efficiency of CO photoreduction. Herein, we report that the plasmonic coupling effect of Pt and Au nanoparticles (NPs) profoundly enhances the efficiency of CO reduction through dry reforming of methane reaction assisted by light illumination, reducing activation energies for CO reduction ∼30% below thermal activation energies and achieving a reaction rate 2.4 times higher than that of the thermocatalytic reaction. UV-visible (vis) absorption spectra and wavelength-dependent performances show that not only UV but also visible light play important roles in promoting CO reduction due to effective localized surface plasmon resonance (LSPR) coupling between Pt and Au NPs. Finite-difference time-domain simulations and in situ diffuse reflectance infrared Fourier transform spectroscopy further reveal that effective coupling LSPR effect generates strong local electric fields and excites high concentration of hot electrons to activate the reactants and intermediate species, reduce the activation energies, and increase the reaction rate. This work provides a new pathway toward the efficient plasmon-enhanced chemical reactions via reducing the activation energies by utilizing solar energy.

Infrared wavelength selective thermal emission based on Tamm plasmon polaritons (TPPs) is experimentally demonstrated. Unlike conventional TPP structures having a thin metal layer on a DBR, the proposed structure has a thick metal under a DBR which is more robust for thermal radiation. The number of DBR pairs is a critical factor to maximize the narrowband emission: It has to satisfy the impedance matching condition, which varies with the choice of metal film. The proposed structure can achieve twice higher Q-factor for the measured emissivity compared to typical plasmonic thermal emitters. The structure is one dimensional, only consists of multilayers, and free from nano-patterning, offering a practical design in applications such as gas sensing, narrowband IR sources and in thermophotovoltaics. TOC

A novel CO2 photoreduction method, CO2 conversion through methane reforming into syngas (DRM) was adopted as an efficient approach to not only reduce the environmental concentration of the greenhouse gas CO2 but also realize the net energy storage from solar energy to chemical energy. For the first time it is reported that gold, which was generally regarded to be inactive in improving the performance of a catalyst in DRM under thermal conditions, enhanced the catalytic performance of Rh/SBA-15 in DRM under visible-light irradiation (1.7 times, CO2 conversion increased from 2100 to 3600 μmol g(-1) s(-1)). UV/Vis spectra and electromagnetic field simulation results revealed that the highly energetic electrons excited by local surface plasmon resonances of Au facilitated the polarization and activation of CO2 and CH4 with thermal assistance. This work provides a new route for CO2 photoreduction and offers a distinctive method to photocatalytically activate nonpolar molecules.

We propose a combined fabrication method of reactive ion etching and largescale colloidal mask to fabricate mid-infrared metamaterial perfect absorbers using aluminumaluminum oxide-aluminum trilayers. The absorptivities of the fabricated samples reached as high as 98% and the absorption bandwidths were comparable to those of the absorbers based on gold or silver. Following Kirchhoff's law, their emission spectra exhibited sharp single emission peaks indicating high potential as narrow-band infrared emitters. The results obtained here demonstrate that earth-abundant aluminum is a high-performance plasmonic materials in the mid-infrared range, and open up a route for fabricating cost-effective scalable plasmonic devices such as efficient light harvesting structures, thermal emitters and infrared sensors.

Methanol synthesis via carbon dioxide (CO2) reduction is challenging and important because this technology can convert CO2 by solar-or wind-generated hydrogen into liquid fuel. The present work introduces the visible light as an external stimulus and for the first time demonstrates that methanol synthesis over Cu/ZnO catalysts can be effectively promoted by solar energy under atmospheric pressure.Experimental and theoretical studies document that hot electrons were photo-excited by localized surface plasmon resonance (LSPR) on Cu nanoparticles and such photo-excited hot electrons could transfer to ZnO through the metal-support interfaces.The hot electrons on Cu and ZnO synergistically facilitated the activation of reaction intermediates. Consequently, the activation energy was reduced by 40% and the methanol synthesis activity was promoted by 54%. This work provides a new strategy towards synthesis of liquid fuel via CO2 reduction under low pressure and sheds new light on the mechanism of photo-mediated catalysis.

We report the fabrication of titanium nitride (TiN) films with the “best” plasmonic behavior reported so far by the pulsed laser deposition method. Even though the deposition is done at room temperature (∼25 °C) and grown on an amorphous native oxide of a silicon wafer, the plasmonic property of the TiN is comparable to that of gold, which is a conventional plasmonic material in the visible to near-infrared region. Because of the highly plasmonic nature of the TiN, the near field around the TiN nanostructure can be as high as that of a gold nanostructure. A room-temperature process without a strict requirement on the substrate allows depositing a TiN film even on a flexible polymer film without degrading its property. Our results pave the way for using TiN as a truly practical plasmonic material, replacing the use of noble metals.