Structural, optical, electrochemical and electrical studies of Bi2O3@rGO nanocomposite

Bismuth oxide incorporated reduced graphene oxide (Bi2O3@rGO) nanocomposite containing different bismuth nitrate Bi(NO3)3 concentrations were synthesized via facile in-situ chemical reduction technique. The SEM image of Bi2O3@rGO nanocomposite revealed a flower-shaped morphology with Bi2O3 nanoparticles over rGO sheets with an average particle size ranging within 103 nm–326 nm. The crystallite size of Bi2O3@rGO nanocomposite varied from 10.42 nm to 25.62 nm with the increasing amount of Bi(NO3)3 content into it. The vibration signatures of Bi–O, Bi–O–Bi, C–O, CC, CO, C–H2, and O–H bonds were obtained at 446 cm−1, 846 cm−1, 1034 cm−1, 1558 cm−1, 1729 cm−1, 2901 cm−1 and (3205–3261) cm−1 respectively from the FTIR analysis of Bi2O3@rGO nanocomposite. The bandgap of Bi2O3@rGO nanocomposite decreased from 3.63 eV to 2.32 eV with the variation of Bi(NO3)3 content from 5 mM to 25 mM respectively. The atomic percentage of O (1s), N (1s), C (1s), Bi (4d), Bi (4f) and Bi (5d) were varied as 13.64–13.06 at.%, 1.81–1.22 at.%, 64.46–43.14 at.%, 12.96–27.72 at.%, 3.59–7.35 at.% and 3.55–7.51 at.% respectively with increasing the Bi(NO3)3 conc. from 5 mM to 25 mM. The maximum specific capacitances of 690.88 F/g and 1248.355 F/g were exhibited by 25 mM Bi2O3@rGO nanocomposite at 5 mV/s scan rate and 1 A/g current density respectively, also besides achieving the highest Ecorr value of 0.107 V from the corrosion analysis. Moreover, I–V characteristics for Bi2O3@rGO nanocomposites exhibit diode characteristic curves.