Rahat Javaid

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

Summary The inner surface of a metallic tube (i.d. 0.5 mm) was coated with a palladium (Pd)-based thin metallic layer by flow electroless plating. Simultaneous plating of Pd and silver (Ag) from their electroless-plating solution produced a mixed distributed bimetallic layer. Preferential acid leaching of Ag from the Pd–Ag layer produced a porous Pd surface. Hydrogenation of p-nitrophenol was examined in the presence of formic acid simply by passing the reaction solution through the catalytic tubular reactors. p-Aminophenol was the sole product of hydrogenation. No side reaction occurred. Reaction conversion with respect to p-nitrophenol was dependent on the catalyst layer type, the temperature, pH, amount of formic acid, and the residence time. A porous and oxidized Pd (PdO) surface gave the best reaction conversion among the catalytic reactors examined. p-Nitrophenol was converted quantitatively to p-aminophenol within 15 s of residence time in the porous PdO reactor at 40 °C. Evolution of carbon dioxide (CO2) was observed during the reaction, although hydrogen (H2) was not found in the gas phase. Dehydrogenation of formic acid did not occur to any practical degree in the absence of p-nitrophenol. Consequently, the nitro group was reduced via hydrogen transfer from formic acid to p-nitrophenol and not by hydrogen generated by dehydrogenation of formic acid.

One-Step Growth of Iron–Nickel Bimetallic Nanoparticles on FeNi Alloy Foils: Highly Efficient Advanced Electrodes for the Oxygen Evolution Reaction

Electrochemical water splitting is an important process to produce hydrogen and oxygen for energy storage and conversion devices. However, it is often restricted by the oxygen evolution reaction (OER) due to its sluggish kinetics. To overcome the problem, precious metal oxide-based electrocatalysts, such as RuO2 and IrO2, are widely used. The lack of availability and the high cost of precious metals compel researchers to find other resources for the development of cost-effective, environmentally friendly, earth-abundant, nonprecious electrocatalysts for OER. Such catalysts should have high OER performance and good stability in comparison to those of available commercial precious metal-based electrocatalysts. Herein, we report an inexpensive fabrication of bimetallic iron-nickel nanoparticles on FeNi-foil (FeNi4.34@FeNi-foil) as an integrated OER electrode using a one-step calcination process. FeNi4.34@FeNi-foil obtained at 900 °C shows superior OER activity in alkaline solution with an overpotential as low as 283 mV to achieve a current density of 10 mA cm-2 and a small Tafel slope of 53 mV dec-1. The high performance and durability of the as-prepared nonprecious metal electrode even exceeds those of the available commercial RuO2 and IrO2 catalysts, showing great potential in replacing the expensive noble metal-based electrocatalysts for OER.

Green Synthesis of Silver Nanoparticles by Pulsed Laser Irradiation: Effect of Hydrophilicity of Dispersing Agents on Size of Particles

Synthesis of homogeneous spherical silver nanoparticles (Ag NPs) was conducted successfully by photochemical reduction of silver ions (Ag+) (10-4 M) using near ultraviolet (UV) pulsed laser (355 nm) irradiation in an aqueous solution of surfactant sodium dodecyl sulphate (SDS) and cetyltrimethylammonium bromide (CTAB). Higher concentration of SDS and CTAB facilitated dispersion of reduced silver salt. Size of NPs was 72 and 163 nm in SDS and CTAB, respectively. Precursor silver acetate salt was irradiated for 30 min. Effect of surfactant concentration, irradiation time, and hydrophilicity of surfactants were investigated. Amount of Ag+ ions reduced increased with surfactant concentration and irradiation time. Note: This article was retracted by the corresponding author from the journal “Advances in Nanoparticles” on an honest error and data still valid note. In this published article the electron generation by biphotonic mechanism has not been claimed as was done in the above retracted article. Introduction For last two decades synthesis of nono-metallic particles is gaining interest of researchers all over the world [1-4]. Favorably improved optical, electrical, magnetic, and pharmaceutical [5-7] properties of these nanocomposites make them potential candidates for catalysts, semiconductors, photo-voltic devices and medical applications for diagnosis and treatment [8,9] compared to bulk materials. In early period nanoparticles were synthesized in few milligram amount using toxic bulk organic solvents in inverted micelles for academic purposes [10]. In next step researchers were successful in synthesizing nanomaterials in large amount using severe conditions of high temperature and pressure [11]. Break through was obtained when Shervani and Yamamoto [12,13] discovered method of bulk nanoparticles production in glucose–water solution without addition of reducing agent at room temperature and pressure. Continuous synthesis of nanoparticles and particles adsorbed on charcoal surface were established for mass production in kilogram amount using a cheap micro-space continuous flow reactor, operated by ordinary pumps, technology under ambient conditions [14]. Catalytic activities of such nanoparticles were extraordinary high due large surface area and small size of particles when employed as catalysts. In top-down method where nanocrystals are removed from the substrate by high energy laser ablation is common [15-17]. Correard, et al. [18] prepared Au NPs by femtosecond laser ablation method in aqueous biocompatible solution of dextran and polyethylene glycol for medical applications. Authors have obtained blood red color Au NPs dispersed in water and had a prominent band at 520 nm in UV-vis spectrum. Size of NPs was in the range of 20-30 nm. In bottom up approach, Abid, et al. [19] prepared Ag NPs by reduction of AgNO3 in aqueous solution by high intense laser irradiation of pulse energy 12-14 mJ. Authors tested addition of 2-propanol in SDS solution and noticed that propanol addition decreases silver ions reduction. None of the authors investigated effect of surfactant hydrophilicity and anion or cationic nature of surfactant. In this article, we have described bottom up preparation of nanosized Ag NPs when silver salt exposed to intense nanosecond (ns) pulsed laser irradiation in SDS and CTAB aqueous solution. The effect of hydrophilicity of surfactants on NPs yield has been reported first. The method is important from green synthesis viewpoint since it does not involve addition of toxic reducing agents and yield and size of particles can be controlled by adjusting the laser irradiation time and type of surfactants used. The research is important from viewpoint of laser irradiation method application in continuous flow microspace reactors for production of nanomaterials on large scale in several grams in short time. Experimental Materials Silver acetate of 99.0 % purity was purchased from Sigma-Aldrich. Sodium dodecyl sulphate (SDS) and cetyl trimethyl ammonium bromide (CTAB) were from Wako Pure Chemicals, Co. Japan. Water used for samples’ preparation was pure and deionized (resistivity, 18 M Ω-cm). Preparation of silver nanoparticles To disperse reduced Ag NPs two kinds of stabilizing agents CTAB a cationic surfactant and SDS an anionic surfactant were used. In all experiments, a stock aqueous solution of silver acetate precursor salt of 0.01M was prepared in water. Salt concentration was kept at 10-4 M or 5×10-4 M. Concentration of stabilizing agents for CTAB was kept in *Correspondence to: Shervani Z, Food and Energy Security Research and Product Centre, Sendai, Japan, E-mail: shervani.nanotek@gmail.com