Novel electroanalysis of hydroxyurea at glassy carbon and gold electrode surfaces

A simple and a novel electroanalysis of hydroxyurea (HU) drug at glassy carbon and gold electrode was investigated for the first time using cyclic, linear sweep and differential pulse voltammetric techniques. The oxidation of HU was irreversible and exhibited a diffusion controlled process on both electrodes. The oxidation mechanism was proposed. The dependence of the current on pH, the concentration, nature of buffer, and scan rate was investigated to optimize the experimental conditions for the determination of HU. It was found that the optimum buffer pH was 7.0, a physiological pH. In the range of 0.01 to 1.0 mM, the current measured by differential pulse voltammetry showed a linear relationship with HU concentration with limit of detection of 0.46 µM for glassy carbon electrode and 0.92 µM for gold electrode. In addition, reproducibility, precision and accuracy of the method were checked as well. The developed method was successfully applied to HU determination in pharmaceutical formulation and human biological fluids. The method finds its applications in quality control laboratories and pharmacokinetics

Candle Soot Nanoparticles versus Multiwalled Carbon Nanotubes as a High-Performance Cathode Catalyst for Li–CO2Mars Batteries for Mars Exploration

Increased CO2 emissions on the earth causing global warming and climate change have provided a thrust to explore Li-CO2 battery chemistry, where CO2 is used as an energy carrier. In addition, the occurrence of CO2 as a major natural abundant gas in the Martian atmosphere opens the possibility of using Li-CO2 batteries for interplanetary Mars missions. In this work, we aim to investigate facile and inexpensive candle soot carbon nanoparticles as a cathode catalyst against commercially available multiwalled carbon nanotubes (MWCNTs) for stable and high-performance Li-CO2 batteries for Mars exploration. The unique interconnected morphology and higher surface area of candle soot nanoparticles facilitate better reversibility (more than 80 cycles) compared to MWCNTs even at a high current density of 200 mA g-1 with a cutoff capacity of 500 mAh g-1. The full discharge capacity for candle soot nanoparticles was measured to be 5318 mAh g-1 with a coulombic efficiency of 42% as compared to 16% for MWCNTs. The rate capability studies were performed to establish the ability to operate the system reversibly at different current densities in a simulated Martian atmosphere. The outcome of this study paves the way toward developing a candle soot cathode-based practicable Li-CO2 battery for utilization on Mars

Cubic Mo6S8-Efficient Electrocatalyst Towards Hydrogen Evolution Over Wide pH Range

Hydrogen evolution from aqueous medium is one of the fundamental processes in electrochemistry and is an important aspect of energy conversion and storage systems. Tremendous efforts to find cheap, efficient and durable electrocatalysts for the hydrogen evolution reaction (HER) have so far, resulted in various transition metal-based catalysts. In this direction, herein, we report the use of chevral Mo6S8 nanocubes synthesized by a simple precipitation method that exhibits high catalytic activity. The catalyst is very active in aqueous media of different pH, 0.5 M H2SO4, 0.1 M KOH and 3% NaCl with good durability and stability. (C) 2017 Elsevier Ltd. All rights reserved

In Situ/Operando Characterization Techniques: The Guiding Tool for the Development of Li–CO 2 Battery

In recent times, the Li-CO2 battery has gained significant importance arising from its higher gravimetric energy density (1876 Wh kg(-1)) compared to the conventional Li-ion batteries. Also, its ability to utilize the greenhouse gas CO2 to operate an energy storage system and the prospective utilization on extraterrestrial planets such as Mars motivate to practicalize it. However, it suffers from numerous challenges such as (i) the reluctant CO2 reduction/evolution; (ii) solid/liquid/gas interface blockage arising from the deposition of Li2CO3 discharge product on the cathode; (iii) high overpotential to decompose the stable discharge product Li2CO3; and (iv) instability of the electrolytes. Numerous efforts have been undertaken to tackle these challenges by developing catalysts, improving the stability of electrolytes, protecting the anode, etc. Despite these efforts, due to the lack of a decisive confirmation of the reaction mechanisms of the discharging/charging reactions occurring in the system, the progress of the Li-CO2 battery system has been slow. In situ characterization techniques help overcome ex-situ techniques' limitations by monitoring the processes with the progress of a reaction. The current review focuses on bridging the gap in the understanding of the Li-CO2 batteries by exploring the various in situ/operando characterization techniques that have been employed