arXiv subjects

Farshid Mohammadparast

Publications and source records attributed to Farshid Mohammadparast.

4 recordsLinked to original sources

arXiv2022

Tuning Catalytic Activity and Selectivity in Photocatalysis on Dielectric Cuprous Oxide Particles

Dye degradation has been for more than forty years in the scientific community. All these studies have primarily focused on breaking various dyes using catalysts driven by either light or heat. Most studies started to focus on metal-oxides after the discovery of water-splitting by TiO2. Among the many catalysts used plasmonic metal nanostructures have been explored significantly in recent times due to their special property called localized surface plasmon resonances (LSPR). However, facing multiple problems of heat losses and instability, people started to focus on dielectric medium-to-high refractive indexed materials for photonic applications. Most of these dielectric materials have been studied from a physics point of view and less from chemistry. In this work, we have focused on how these materials can be used for tuning selectivity through wavelength-dependent studies by performing methylene blue (MB) dye degradation.

physics.chem-ph↗

arXiv2022

Structure-Property-Performance Relationships of Dielectric Nanostructures for Mie Resonance-Enhanced Dye-Sensitization

Dye-sensitized photocatalytic (DSP) approach is considered as one of the promising approaches for developing visible light- and near-infrared light-responsive photocatalysts. DSP systems are still affected by significant drawbacks, such as low light absorption efficiency. Recently, it has been demonstrated that the plasmonic metal nanostructures can be used to enhance the light absorption efficiency and the overall dye-sensitization rate of DSP systems through the plasmonic Mie resonance-enhanced dye-sensitization approach. In this contribution, we report an alternate and novel approach, dielectric Mie resonance-enhanced dye sensitization. Specifically, we demonstrate that the dielectric Mie resonances in cuprous oxide (Cu2O) spherical and cubical nanostructures can be used to enhance the dye-sensitization rate of methylene blue dye. The Cu2O nanostructures exhibiting dielectric Mie resonances exhibit up to an order of magnitude higher dye-sensitization rate as compared to Cu2O nanostructures not exhibiting dielectric Mie resonances. Our model system developed from finite-difference time-domain simulation predicts a volcano-type relationship between the dye sensitization rate and the size of Cu2O nanostructures. The predicted structure-property-performance relationship is experimentally verified and the optimal size ranges of Cu2O nanospheres and nanocubes are identified. Although we demonstrate the dielectric Mie resonance-enhanced dye-sensitization approach using Cu2O nanostructures, the proposed approach can be used to design a wide range of DSP systems, including CeO2, α-Fe2O3, and TiO2 nanostructures-based DSP systems.

physics.optics↗

arXiv2022

Structure-Property-Performance Relationships of Cuprous Oxide Nanostructures for Dielectric Mie Resonance-Enhanced 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 to 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 using Cu2O particles here, based on our FDTD simulations, we anticipate the same can be achieved with other metal oxide photocatalysts, including CeO2, α-Fe2O3, and TiO2.

physics.app-ph↗

arXiv2022

Tailoring Mie Resonances in Cupric Oxide Particles for Use as Nanoantennas

The field of nano-optics has grown with plasmonic metals. Metals such as silver, gold, and copper nanoparticles, can concentrate electromagnetic (EM) fields at the nanoscale, due to the special property called localized surface plasmon resonance (LSPR). This laid the foundation for a wide range of applications, including nanoscale optics, solar energy harvesting, photocatalysis, and biosensing. However, there are inherent problems associated with plasmonic metals, such as high heating losses, and their inability to be scaled-up like semiconductor fabrication processes. In addition, the field enhancement is restricted only to electric fields. All together these inhibit the broader use of PMNs in practical applications. In this work, we report submicron cupric oxide (CuO) particles with a medium refractive index that can exhibit strong electric and magnetic Mie resonances with strong extinction/scattering cross-sections comparable to or slightly exceeding those of their plasmonic counterparts. Through the development of particle synthesis techniques with strong shape and size control, optical spectroscopy, and finite-difference-time-domain simulations we show that the Mie resonance peak wavelengths are size- and shape-dependent. This gives tunability in the visible to near-infrared regions for harvesting a wider fraction of the solar spectrum. Therefore, submicron CuO particles exhibit strong potential in emerging as high-performance alternatives to PMNs. The strong electric and magnetic Mie-resonance-mediated nanoantenna effect attribute that CuO particles can be potentially used in a plethora of applications, including surface-enhance Raman spectroscopy, metamaterials, photocatalysis, and photovoltaics.

physics.optics↗