Showing papers by "Kothandaraman Ramanujam published in 2019"
TL;DR: In this article, the authors used activated porous carbon (ACTS-900) derived from Tamarindus indica, a bio-source, via KOH activation and carbonization at 900°C was used as an active electrode material for supercapacitor (SC) applications.
Abstract: Herein, activated porous carbon (ACTS-900) derived from Tamarindus indica, a bio-source, via KOH activation and carbonization at 900 °C was used as an active electrode material for supercapacitor (SC) applications. In the three-electrode configuration, ACTS-900 shows the maximum specific capacitance (Cs,3E) of 225 F g−1 at 50 mV s−1 and 249 F g−1 at 0.5 A g−1 in 1 M H2SO4. A high-performance, bio-based, environmentally benign and cost-effective chitosan/poly(ethylene glycol)-ran-poly(propylene glycol) [Ch/poly(EG-ran-PG)]-based polymer blend was employed as a membrane-cum-separator as well as a green binder in the electrodes. The blend polymer membrane was prepared by mixing chitosan (Ch) and poly(EG-ran-PG) in a 1 : 1 weight ratio in a 1% aqueous acetic acid solution followed by drying under controlled evaporation. The blend membrane showed high porosity (2 μm–7 μm diameter pores) and excellent thermal (up to 250 °C), chemical (in 1 M H2SO4), electrochemical (up to 1.21 V) and mechanical stability (up to 39 MPa under tensile loading). The performance of a symmetric two-electrode SC device was evaluated using a H2SO4-(1 M)-soaked-Ch/poly(EG-ran-PG) membrane and ACTS-900 active electrode materials. The obtained results were compared with those obtained using commercially available binders and membranes. The single electrode specific capacitances (Cs,2E) in the symmetrical SC device were 193 F g−1 at 50 mV s−1 and 132 F g−1 at 2 A g−1 with H2SO4-(1 M)-soaked-Ch/poly(EG-ran-PG) as the membrane and binder. The maximum energy density and power density of the SC device are 4.7 W h kg−1 (at 1 A g−1) and 2.5 kW kg−1 (at 5 A g−1), respectively. Due to the superior wetting properties of the blend membrane and binder, excellent capacity retention was observed (∼99%) over 6000 cycles at the current density of 3.5 A g−1. As a proof-of-concept, a red light-emitting diode was illuminated using three serially connected 3 V SC stacks.
31 citations
9 citations
07 Aug 2019
7 citations
TL;DR: The oxygen active center namely copper (I) generation during ORR is understood by the reduction peak in cyclic voltammetry as well in the XPS analysis, which supports the good activity of Cu-BTT MOF.
Abstract: Inspired by copper-based oxygen reduction biocatalysts, we have studied the electrocatalytic behavior of a Cu-based MOF (Cu-BTT) for oxygen reduction reaction (ORR) in alkaline medium. This catalyst reduces the oxygen at the onset (Eonset ) and half-wave potential (E1/2 ) of 0. 940 V and 0.778 V, respectively. The high halfway potential supports the good activity of Cu-BTT MOF. The high ORR catalytic activity can be interpreted by the presence of nitrogen-rich ligand (tetrazole) and the generation of nascent copper(I) during the reaction. In addition to the excellent activity, Cu-BTT MOF showed exceptional stability too, which was confirmed through chronoamperometry study, where current was unchanged up to 12 h. Further, the 4-electrons transfer of ORR kinetics was confirmed by hydrodynamic voltammetry. The oxygen active center namely copper(I) generation during ORR has been understood by the reduction peak in cyclic voltammetry as well in the XPS analysis.
6 citations