Oxalic acid-induced assembly of CoxNi1−x-bimetallic polyaniline nanocomposite: a bifunctional material for supercapacitor and chromium removal applications

Here, we aimed to synthesize an oxalic acid (Oxa)-induced cobalt (Co) and nickel (Ni) bimetallic assembled polyaniline (PANi) nanocomposite as a bifunctional material through a microwave-assisted method, where the Oxa was used as a complexing agent to determine the final particle size distribution of the metal dispersion. The as-prepared materials were characterized well using FTIR, PXRD, SEM, XPS, BET and zeta potential analysis. Among the prepared Co–Oxa, Ni–Oxa, Co–Oxa–Ni and Co–Oxa–Ni@PANi electrode materials, Co–Oxa–Ni@PANi nanocomposite exhibited a higher specific capacitance (1420 F g−1) at the current density of 1 A g−1, and better recyclability in a three-electrode system with 1 M KOH electrolyte, where the electrolyte could diffuse between the carbon layers of PANi provides sufficient space to buffer the volume change. Besides, the chromium [Cr(VI)] adsorption density on Co–Oxa–Ni@PANi nanocomposite was much higher at solution pH conditions (5.3) compared to other materials developed for this study. The maximum uptake of Cr(VI) on Co–Oxa–Ni@PANi nanocomposite was found to be 52.52 mg g−1 with a contact time of 240 min at pH 5.3. The synthesized material was regenerated up to five times with 0.1 M NaOH solution as an eluent. A very high degree of selectivity and no dissolution was observed for the prepared nanocomposite in the selectivity and stability studies, respectively. The findings of this study are of great importance in the development of multitalented materials by the one-pot two-step (1p2s) method. These materials can be used in both fields of energy and environment with minimal energy consumption.