Supercapacitor activity studies of a unique triangular oxo-vanadate-bisphosphonate composite with activated carbon

Abstract

Electrochemical studies have been performed on a hybrid inorganic–organic oxo-vanadate (IV)-bisphosphonate assembly, viz. (NH<inf>4</inf>)<inf>2</inf>[H<inf>6</inf>(VIVO)<inf>3</inf>(O){O<inf>3</inf>P-C(OH)(CH<inf>2</inf>-4-C<inf>5</inf>NH<inf>4</inf>)-PO<inf>3</inf>}<inf>3</inf>]•26H<inf>2</inf>O [V<inf>3</inf>-BP]. The compound has a triangular shaped structure consisting of reduced vanadium (IV) with 1-hydroxo-2-(4-pyridyl) ethylidene-1,1-bisphosphonic acid. Composites of this compound were prepared with activated carbon (AC), viz. AC-V<inf>3</inf>-BP, and extensively characterized using various analytical techniques (e.g., FT-IR, TGA, P-XRD, FESEM, EDX, and BET) to study the interaction of V<inf>3</inf>-BP with the activated carbon support. Electrochemical properties of AC-V<inf>3</inf>-BP were studied, vis-à-vis its supercapacitor behavior, with the electrochemical performance of the composite AC-V<inf>3</inf>-BP material tested in 0.1 (M) H<inf>2</inf>SO<inf>4</inf> aqueous electrolytic solution. The composite exhibits a specific capacitance of 140.8 F g−1 with a specific energy of 19.56 W kg−1. With such interesting capacitive properties, electrochemical cells prepared with this material were observed to light up red and blue LED bulbs for 90 and 20 s, respectively, suggesting a substantial power density of the materials. The respective electrode prepared from the composite was also observed to retain 79.23% of the electrode stability after 4500 cycles. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.