Indian Institute of Science

About: Indian Institute of Science is a education organization based out in Bengaluru, India. It is known for research contribution in the topics: Thin film & Population. The organization has 30960 authors who have published 62497 publications receiving 1257765 citations. The organization is also known as: IISC & IISc.

A comprehensive analysis and rational designing of efficient Fe-based oxygen electrocatalysts for metal–air batteries

Abstract: Precious metal based electrocatalysts are considered as the most efficient ones to drive kinetically sluggish oxygen evolution/reduction reactions (OER/ORR) for metal–air batteries and fuel-cells. However, their monofunctionality in addition to their exorbitant cost has stimulated the quest for economically viable bifunctional electrocatalysts for use in next generation electrochemical energy devices. Here, we report Fe–Fe3C encapsulated in Fe–Nx enriched spheres of N-doped carbon nanotubes (FCMR, M = 3, 10, 25, 40 represents the ramping rate of temperature during synthesis) as a potentially enduring, cost effective, highly efficient bifunctional electrocatalyst for total oxygen electrochemistry (ORR and OER) and a comprehensive study to elucidate the role of various Fe moieties. In addition to the improved OER/ORR activities as evident from the better onset potential, lower Tafel slopes and high current densities over commercially available RuO2/Pt–C electrocatalysts and several recently reported state-of-the-art bi-functional electrocatalysts, FC10R shows a current retention value of ∼93 and ∼98% after the accelerated cyclic stability test for the OER and ORR, respectively. The preferable 4e− pathways and suppressed peroxide generation in the ORR by FC10R further ensure maximum electrochemical energy harvesting. Remarkably, the complete oxygen electrochemistry of FC10R in alkaline medium as evaluated from ΔE (=Ej(OER) = 10 − E1/2(ORR) = 0.758 V) is significantly lower than that of commercially available/recently reported electrocatalysts and advocates the minimum cyclic loss. The overall study elucidates the synergistic effect of Fe–Nx coordination and Fe3C moieties on oxygen electrochemistry, and FC10R has shown its potential to serve as a non-precious metal based bifunctional electrocatalyst for next generation electrochemical energy conversion and storage devices. Finally, a prototype Al–air battery arrangement using FC10R as an air-cathode for powering a green light emitting diode has been demonstrated.

Nonequilibrium phase transition in the kinetic Ising model: Divergences of fluctuations and responses near the transition point

Abstract: The nonequilibrium dynamic phase transition in the kinetic Ising model in the presence of an oscillating magnetic field is studied by Monte Carlo simulation. The fluctuation of the dynamic older parameter is studied as a function of temperature near the dynamic transition point. The temperature variation of appropriately defined ''susceptibility'' is also studied near the dynamic transition point. Similarly, the fluctuation of energy and appropriately defined ''specific heat'' is studied as a function of temperature near the dynamic transition point. In both cases, the fluctuations (of dynamic order parameter and energy) and the corresponding responses diverge (in power law fashion) near the dynamic transition point with similar critical behavior (with identical exponent values).