Core-shell Au/Ag nanoparticles embedded in silicate sol-gel network for sensor application towards hydrogen peroxide

The electrocatalytic activity of core-shell Au100-x Agx (x = 15, 27, 46, and 60) bimetallic nanoparticles embedded in methyl functionalized silicate MTMOS network towards the reduction of hydrogen peroxide was investigated by using cyclic voltammetry and chronoamperometric techniques. Core-shell Au/Ag bimetallic nanoparticles were characterized by absorption spectra and HRTEM. The MTMOS silicate sol-gel embedded Au73Ag27 core-shell nanoparticles modified electrode showed better synergistic electrocatalytic effect towards the reduction of hydrogen peroxide when compared to monometal MTMOS-Aunps and MTMOS-Agnps modified electrodes. These modified electrodes were studied without immobilizing any enzyme in the MTMOS sol-gel matrix. The present study highlights the influence of molar composition of Ag nanoparticles in the Au/Ag bimetallic composition towards the electrocatalytic reduction and sensing of hydrogen peroxide in comparison to monometal Au and Ag nanoparticles

Photoreduction of nitrite to ammonia by metal phthalocyanines-adsorbed membrane

The metal phthalocyanines (MPCs)-adsorbed Nafion (Nf) membranes (Nf/MPCs) are prepared and used for the photocatalytic reduction of nitrite ion. The selective formation of NH4OH is observed when the Nf/MPC membrane is dipped in nitrite ion solution and photolysed in the presence of sacrificial electron donor such as triethanolamine (TEA). The Nf/MPC membranes behave as p-type semiconductors. The photosensitized reaction mechanism of the photocatalytic reduction of NO2 - to NH4 + formation is explained by the reaction of the e- c b with nitrite ion and the hole (h+ v b) with TEA

Boosting photovoltaic performance of dye-sensitized solar cells using silver nanoparticle-decorated N,S-co-doped-TiO2 photoanode

A silver nanoparticle-decorated N,S-co-doped TiO2 nanocomposite was successfully prepared and used as an efficient photoanode in high-performance dye-sensitized solar cells (DSSCs) with N719 dye. The DSSCs assembled with the N,S-TiO2@Ag-modified photoanode demonstrated an enhanced solar-to-electrical energy conversion efficiency of 8.22%, which was better than that of a DSSC photoanode composed of unmodified TiO2 (2.57%) under full sunlight illumination (100mWcm−2 , AM 1.5 G). This enhanced efficiency was mainly attributed to the reduced band gap energy, improved interfacial charge transfer, and retarded charge recombination process. The influence of the Ag content on the overall efficiency was also investigated, and the optimum Ag content with N,S-TiO2 was found to be 20wt%. Because of the enhanced solar energy conversion efficiency of the N,STiO2@Ag nanocomposite, it should be considered as a potential photoanode for high-performance DSSCs

Titania@gold plasmonic nanoarchitectures: an ideal photoanode for dye-sensitized solar cells

Rapid depletion of fossil fuel leads to increasing energy demand in the near future and it will force us to seek alternative eco-friendly and renewable energy resources. Dye-sensitized solar cells (DSSCs) represent one of the most promising emerging technologies for light-to-electrical energy conversion. Titania is the most widely used photoanode, but its limited performance due to poor interfacial charge transfer and limited optical properties has motivated the quest for modified titania materials to overcome this issue. The emergence of gold–titania nanocomposite materials (Au–TiO2) as a new component to fabricate the DSSCs has opened up new ways to effectively utilize renewable energy sources. This review article mainly focuses on the superior photovoltaic performance of Au–TiO2 nanocomposite materials based photoanode in DSSCs. The review justifies how plasmonic Au influences the visible light absorption, electrons transfer process and solar energy conversion efficiency. Data supporting and confirming the superiority of Au on TiO2 or TiO2 on Au are briefly presented to justify the possibility of electron transfer from dye to conduction band of the TiO2 through Au. This account further highlights the recent developments in these area and points out some specific Au–TiO2 plasmonic nanoarchitectures as photoanode for improved device performance

Amalgamation based optical and colorimetric sensing of mercury (II) ions with silver@graphene oxide nanocomposite materials

The article describes a facile method for the preparation of a conjugate composed of silver nanoparticles and graphene oxide (Ag@GO) via chemical reduction of silver precursors in the presence of graphene oxide (GO) while sonicating the solution. The Ag@GO was characterized by X-ray photoelectron spectroscopy, X-ray powder diffraction, and energy-dispersive X-ray spectroscopy. The nanocomposite undergoes a color change from yellow to colorless in presence of Hg(II), and this effect is based on the disappearance of the localized surface plasmon resonance absorption of the AgNPs due to the formation of silver-mercury amalgam. The presence of GO, on the other hand, prevents the agglomeration of the AgNPs and enhances the stability of the nanocomposite material in solution. Hence, the probe represents a viable optical probe for the determination of mercury(II) ions in that it can be used to visually detect Hg(II) concentrations as low as 100 μM. The instrumental LOD is 338 nM

Synthesis, antibacterial activities and molecular docking studies of ethyl 3-(4-substituted phenyl) propanoates as targeted antibiotics

Type II fatty acid synthesis (FAS II) pathway has been recently reported as an attractive targeting for their efficacy against infections caused by multi-resistant Gram-positive and Gram-negative bacteria. Among the related FAS II enzymes, beta ketoacyl-acyl carrier protein synthase (KAS), is an essential target for novel antibacterial drug design. Five novel Ethyl-3-(4-substituted phenyl) propanoates have been synthesized, characterized and screened for antibacterial activity. The inhibitory activities against Escherichia coli b-ketoacyl-acyl carrier protein synthase III (ecKAS III) were investigated by molecular docking simulation. Compounds which posses both good inhibitory activity and well binding affinities were compared their antibacterial activities against gram negative and gram-positive bacterial strains were tested, expecting to exploit potent antibacterial agent with broad-spectrum antibiotics activity. Compounds 4b, 4c, 4d exhibits significant activity and ethyl-3-(4-chlorophenyl)propanaoate (4b) exhibits highest antibacterial activity against all the bacteria among the synthesized compounds.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Gold-silver@TiO2 nanocomposite-modified plasmonic photoanodes for higher efficiency dye-sensitized solar cells

In the present investigation, gold–silver@titania (Au–Ag@TiO2) plasmonic nanocomposite materials with different Au and Ag compositions were prepared using a simple one-step chemical reduction method and used as photoanodes in high-efficiency dye-sensitized solar cells (DSSCs). The Au–Ag incorporated TiO2 photoanode demonstrated an enhanced solar-to-electrical energy conversion efficiency of 7.33%, which is ∼230% higher than the unmodified TiO2 photoanode (2.22%) under full sunlight illumination (100 mW cm−2, AM 1.5G). This superior solar energy conversion efficiency was mainly due to the synergistic effect between the Au and Ag, and their surface plasmon resonance effect, which improved the optical absorption and interfacial charge transfer by minimizing the charge recombination process. The influence of the Au–Ag composition on the overall energy conversion efficiency was also explored, and the optimized composition with TiO2 was found to be Au75–Ag25. This was reflected in the femtosecond transient absorption dynamics in which the electron–phonon interaction in the Au nanoparticles was measured to be 6.14 ps in TiO2/Au75:Ag25, compared to 2.38 ps for free Au and 4.02 ps for TiO2/Au100:Ag0. The slower dynamics indicates a more efficient electron–hole separation in TiO2/Au75:Ag25 that is attributed to the formation of a Schottky barrier at the interface between TiO2 and the noble metal(s) that acts as an electron sink. The significant boost in the solar energy conversion efficiency with the Au–Ag@TiO2 plasmonic nanocomposite showed its potential as a photoanode for high-efficiency DSSCs

Photoelectrocatalytic reactions of metal complexes at chemically modified electrodes

One of the outstanding properties of the ion-exchange membranes is their multiphase structure with microheterogeneous environment. Recently we have shown that ion-exchange membranes such as Nafion and clay can be effectively used in preparing chemically modified electrodes with adsorbed photoactive and electroactive molecules. A new photogalvanic cell was constructed by coating one electrode with Nafion-[Ru(bpy)<SUB>3</SUB>]<SUP>2+</SUP> and the other with clay-[Ru(bpy)<SUB>3</SUB>]<SUP>2+</SUP>. This new photogalvanic cell showed an additive photogalvanic response on visible light irradiation. The quenching rate constants,k<SUB>q</SUB>, for the reaction of excited state [Ru(bpy)<SUB>3</SUB>]<SUP>2+</SUP> adsorbed into the membrane with Fe<SUP>3+</SUP> ion and cobalt(III) complexes were determined by photoelectrochemical methods. The photoelectrocatalytic reduction of oxygen to hydrogen peroxide at chemically modified electrodes was carried out by using [Ru(bpy)<SUB>3</SUB>]<SUP>2+</SUP> as sensitizer and macrocyclic cobalt(III) complexes as electron relay

Rational design of solar cells for efficient solar energy conversion

Preface Solar cell technology is a potential alternative to overcome the issues related to energy demand and environmental pollution caused by fossil fuels. Dye‐sensitized solar cells, organic solar cells, polymer solar cells, perovskite solar cells, and quantum dot solar cells are promising next‐generation alternative renewable energy technology to substitute for fossil fuels and other energy sources due to their high performance, ease of fabrication, long‐term stability, and low manufacturing cost. This new book gathers and surveys a variety of novel ideas that have emerged in the fields of dye‐sensitized solar cells, organic solar cells, polymer solar cells, perovskite solar cells, and quantum dot solar cells from over forty experts in the interdisciplinary areas of chemistry, physics, materials science, and engineering and widely explores the materials development and device fabrication in the field of solar cells to achieve higher solar energy conversion efficiency. This book presents a collection of twelve chapters written by researchers who are the leading experts in their fields of research and they explain the strategies needed to overcome the challenges in solar cell fabrication. The first chapter of this book is a succinct summary of the state of the art of the fabrication of plasmonic nanoparticles incorporated into photoanodes for dye‐sensitized solar cells. Chapters 2 and 3 focus more on the aspects of sensitization processes with cosensitizer and natural dyes, and their impact in dye‐sensitized solar cells. Chapters 4 and 5 explore the durability, stability, and performance enhancement strategies needed to adapt polymer and gel electrolytes for use in in dye‐sensitized solar cells. Chapters 6 and 7 discuss the details of replacing the expensive platinum counterelectrode with alternative electrocatalysts to minimize the fabrication cost of dye‐sensitized solar cells. Chapters 8–10 address the key challenges in the fabrication and possible strategies to improve the efficiency of the polymer solar cells with different approaches. Chapter 11 summarizes the possible methodologies to fabricate perovskite solar cells from laboratory scale to industrial scale. Chapter 12 presents the possible role of biomolecules and their charge transfer dynamics in quantum dot solar cells

Aminosilicate sol-gel embedded core-shell (TiO₂-Au)_nps nanomaterials modified electrode for the electrochemical detection of nitric oxide

1388-1393A glassy carbon electrode modified with amine functionalized silicate sol-gel supported core-shell titanium dioxide–gold nanocomposite materials (EDAS/(TiO2-Au)nps) has been prepared and used as an electrochemical sensor for nitric oxide detection. The aminosilicate supported core-shell nanomaterials have been synthesized by the chemical reduction of HAuCl4 and deposition of the formed Aunps on TiO2 nanoparticles in the presence of N-[3-(trimethoxysilyl)propyl]-ethylene diamine as a support matrix and as a reducing agent. The so-prepared EDAS/(TiO2-Au)nps nanomaterials and the corresponding films have been characterized by spectral and electrochemical methods. A set of experimental conditions has been optimized for the fabrication of sensor electrode. The electrochemical properties of the GC/EDAS(TiO2-Au)nps modified electrode and the electrochemical detection of NO have been  studied. The Osteryoung square wave voltammetric measurements reveals that the current response observed at the GC/EDAS(TiO2-Au)nps modified electrode for different concentrations of NO is linear with the  lowest detection limit of 1 M