Decoupling Plasmonic Hot Carrier from Thermal Catalysis via Electrode Engineering.

Increased attention has been directed toward generating nonequilibrium hot carriers resulting from the decay of collective electronic oscillations on metal known as surface plasmons. Despite numerous experimental endeavors, demonstrating hot carrier-mediated photocatalysis without a heating contribution has proven challenging, particularly for single electron transfer reactions where the thermal contribution is generally detrimental. An innovative engineering solution is proposed to enable single electron transfer reactions with plasmonics. It consists of a photoelectrode designed as an energy filter and photocatalysis performed with light function modulation instead of continuously. The photoelectrode, consisting of FTO/TiO2 amorphous (10 nm)/Au nanoparticles, with TiO2 acting as a step-shape energy filter to enhance hot electron extraction and charge-separated state lifetime. The extracted hot electrons were directed toward the counter electrode, while the hot holes performed a single electron transfer oxidation reaction. Light modulation prevented local heat accumulation, effectively decoupling hot carrier catalysis from the thermal contribution.

Ag-Vanadates/GO Nanocomposites by Aerosol-Assisted Spray Pyrolysis: Preparation and Structural and Electrochemical Characterization of a Versatile Material.

In this article, we describe the deposition by aerosol-assisted spray pyrolysis of different types of silver vanadate nanocomposites with and without graphene oxide (GO) on different substrates (carbon paper (CP) and fluorine-doped tin oxide (FTO)). When deposited on CP, different amounts of GO were added to the Ag and V precursor solution to study the effect of GO on the physicochemical properties of the resulting Ag-vanadate. It is shown that the addition of GO leads mainly to the formation of nanoparticles of the Ag2V4O11 phase, whereas Ag2V4O11 and Ag3VO4 are obtained without the addition of GO. The morphology and chemical properties of the composites were determined by scanning and transmission electron microscopies, X-ray diffraction, X-ray photoemission spectroscopy, and UV-visible and Raman spectroscopies. In addition, the photoelectrochemical (PEC) properties of such composites were studied by CV, linear sweep voltammetry, and electrochemical impedance spectroscopy. The ideal Ag x VO y and GO ratio was optimized for obtaining higher photocurrent values and a good stability. The results showed that the presence of GO improves the electrical conductivity of the catalyst layer as well as the electron injection from the oxide to the electrode surface. The deposition of pure Ag2V4O11 on FTO does not lead to samples with stable PEC performances. Samples grown on CP supports showed an efficient electrochemical detection of small amounts of ethylenediamine in water solution.

3D polyaniline porous layer anchored pillared graphene sheets: enhanced interface joined with high conductivity for better charge storage applications.

Here, we report synthesis of a 3-dimensional (3D) porous polyaniline (PANI) anchored on pillared graphene (G-PANI-PA) as an efficient charge storage material for supercapacitor applications. Benzoic acid (BA) anchored graphene, having spatially separated graphene layers (G-Bz-COOH), was used as a structure controlling support whereas 3D PANI growth has been achieved by a simple chemical oxidation of aniline in the presence of phytic acid (PA). The BA groups on G-Bz-COOH play a critical role in preventing the restacking of graphene to achieve a high surface area of 472 m(2)/g compared to reduced graphene oxide (RGO, 290 m(2)/g). The carboxylic acid (-COOH) group controls the rate of polymerization to achieve a compact polymer structure with micropores whereas the chelating nature of PA plays a crucial role to achieve the 3D growth pattern of PANI. This type of controlled interplay helps G-PANI-PA to achieve a high conductivity of 3.74 S/cm all the while maintaining a high surface area of 330 m(2)/g compared to PANI-PA (0.4 S/cm and 60 m(2)/g). G-PANI-PA thus conceives the characteristics required for facile charge mobility during fast charge-discharge cycles, which results in a high specific capacitance of 652 F/g for the composite. Owing to the high surface area along with high conductivity, G-PANI-PA displays a stable specific capacitance of 547 F/g even with a high mass loading of 3 mg/cm(2), an enhanced areal capacitance of 1.52 F/cm(2), and a volumetric capacitance of 122 F/cm(3). The reduced charge-transfer resistance (RCT) of 0.67 Ω displayed by G-PANI-PA compared to pure PANI (0.79 Ω) stands out as valid evidence of the improved charge mobility achieved by the system by growing the 3D PANI layer along the spatially separated layers of the graphene sheets. The low RCT helps the system to display capacitance retention as high as 65% even under a high current dragging condition of 10 A/g. High charge/discharge rates and good cycling stability are the other highlights of the supercapacitor system derived from this composite material.