Low Reducing Potentials Enabled by CaF-Supported Graphene Electrodes in High Impedance Solutions.

We report electrochemical measurements using in situ Raman spectroscopy at graphene/DO interfaces under extremely low applied potentials. Here, the hydrophobic and catalytically inert nature of graphene and the insulating nature of the deionized (DI) water enables potentials as low as = -7 V vs Ag/AgCl to be applied without exceeding 200 μA/cm of current density. At higher currents, bubble formation (i.

Voltage-induced modulation of interfacial ionic liquids measured using surface plasmon resonant grating nanostructures.

We have used surface plasmon resonant metal gratings to induce and probe the dielectric response (i.e., electro-optic modulation) of ionic liquids (ILs) at electrode interfaces.

Achieving Low Voltage Plasma Discharge in Aqueous Solution Using Lithographically Defined Electrodes and Metal/Dielectric Nanoparticles.

Because of the high dielectric strength of water, it is extremely difficult to discharge plasma in a controllable way in the aqueous phase. By using lithographically defined electrodes and metal/dielectric nanoparticles, we create electric field enhancement that enables plasma discharge in liquid electrolytes at significantly reduced applied voltages. Here, we use high voltage (10-30 kV) nanosecond pulse (20 ns) discharges to generate a transient plasma in the aqueous phase.

Photoexcited Hot Electron Catalysis in Plasmon-Resonant Grating Structures with Platinum, Nickel, and Ruthenium Coatings.

We report the electrochemical potential dependence of photocatalysis produced by hot electrons in plasmon-resonant grating structures. Here, corrugated metal surfaces with a period of 520 nm are illuminated with 785 nm wavelength laser light swept as a function of incident angle. At incident angles corresponding to plasmon-resonant excitation, we observe sharp peaks in the electrochemical photocurrent and dips in the photoreflectance consistent with the conditions under which there is wavevector matching between the incident light and the spacing between the lines in the grating.

Dynamic Study of Intercalation/Deintercalation of Ionic Liquids in Multilayer Graphene Using an Alternating Current Raman Spectroscopy Technique.

We report Raman spectra and infrared (IR) imaging collected during the intercalation-deintercalation half cycles in a multilayer graphene (MLG) device (∼100 layers) operating at 0.2-10 Hz. The device consists of a MLG/alumina membrane/copper stack, in which the alumina membrane is filled with ionic liquid [DEME][TFSI], forming an electrochemical cell.

Plasma-enhanced electrostatic precipitation of diesel exhaust particulates using nanosecond high voltage pulse discharge for mobile source emission control.

This study reports enhancement in the electrostatic precipitation (ESP) of diesel engine exhaust particulates using high voltage nanosecond pulse discharge in conjunction with a negative direct current (DC) bias voltage. The high voltage (20 kV) nanosecond pulses produce ion densities that are several orders of magnitude higher than those in the corona produced by a standard DC-only ESP. This plasma-enhanced electrostatic precipitator (PE-ESP) demonstrated 95 % remediation of PM and consumes less than 1 % of the engine power (i.

In Situ Investigation of Ultrafast Dynamics of Hot Electron-Driven Photocatalysis in Plasmon-Resonant Grating Structures.

Understanding the relaxation and injection dynamics of hot electrons is crucial to utilizing them in photocatalytic applications. While most studies have focused on hot carrier dynamics at metal/semiconductor interfaces, we study the in situ dynamics of direct hot electron injection from metal to adsorbates. Here, we report a hot electron-driven hydrogen evolution reaction (HER) by exciting the localized surface plasmon resonance (LSPR) in Au grating photoelectrodes.

Monitoring Reaction Intermediates in Plasma-Driven SO, NO, and NO Remediation Chemistry Using In Situ SERS Spectroscopy.

In situ surface-enhanced Raman scattering (SERS) spectroscopy is used to identify the key reaction intermediates during the plasma-based removal of NO and SO under dry and wet conditions on Ag nanoparticles. Density functional theory (DFT) calculations are used to confirm the experimental observations by calculating the vibrational modes of the surface-bound intermediate species. Here, we provide spectroscopic evidence that the wet plasma increases the SO and the NO removal through the formation of highly reactive OH radicals, driving the reactions to HSO and HNO, respectively.

Enhanced Low-Temperature Thermoelectric Performance in (PbSe)(VSe) Heterostructures due to Highly Correlated Electrons in Charge Density Waves.

We explore the effect of charge density wave (CDW) on the in-plane thermoelectric transport properties of (PbSe)(VSe) and (PbSe)(VSe) heterostructures. In (PbSe)(VSe) we observe an abrupt 86% increase in the Seebeck coefficient, 245% increase in the power factor, and a slight decrease in resistivity over the CDW transition. This behavior is not observed in (PbSe)(VSe) and is rather unusual compared to the general trend observed in other materials.

Hot Electron Driven Photocatalysis on Plasmon-Resonant Grating Nanostructures.

We demonstrate the hot electron injection of photoexcited carriers in an Ag-based plasmon resonant grating structure. By varying the incident angle of irradiation, sharp dips are observed in the reflectance with p-polarized light (electric field perpendicular to grating lines) when there is wavevector matching between the incident light and the plasmon resonant modes of the grating and no angle dependence is observed with s-polarized light. This configuration enables us to compare photoelectrochemical current produced by plasmon resonant excitation with that of bulk metal interband absorption simply by rotating the polarization of the incident light while keeping all other parameters of the measurement fixed.