A novel electrode material for supercapacitor has been developed based on biochemically reduced graphene oxide/zerovalent iron (rGO/Fe$^0$) and polyaniline (PANI) ternary hybrid composite synthesized by interfacial polymerization. The composites were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), ultraviolet–visible absorption (UV–Vis), X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS) and electrical conductivity measurements. The composites exhibited noticeable improvement in electrical conductivity and excellent electrochemical reversibility when compared to bare polymer. The electrochemical properties of the composite electrode are investigated by galvanostatic charge–discharge, electrochemical impedance spectroscopy (EIS) studies. The enhanced specific capacitance with higher conductivities is observed in PANI/rGO/Fe$^0$ (342 F g$^{-1}$) when compared with PANI (182 F g$^{-1}$) and PANI/rGO composites (294 F g$^{-1}$) with a constant current density of 1.0 A g$^{-1}$. The cyclic stability of the composite, following 500 cycles of operations, was at 68.6 (PANI), 80.6 (PANI/rGO) and 95.4% (PANI/rGO/Fe$^0$) of their initial capacitance. The higher conductivity, higher specific capacitance and cyclic self-stability of PANI/rGO/Fe$^0$ ternary composite can provide new prospects in the field energy storage application.

The Cd$_x$Pb$_{1–x}$S thin films with different concentrations of x from 0.2 to 0.8 were synthesized using the chemical bath deposition method. X-ray diffraction (XRD) and Williamson–Hall (W–H) plot gives the crystallite size that decreases with increased concentration. XRD, high-resolution transmission electron microscopy and selected area electron diffraction patterns of the film samples evidence the hexagonal phase structures of both CdS and PbS. Energy-dispersive X-ray confirmed the presence of Cd, Pb and S in the film samples. The transmittance of the film samples increases with the increase in concentration. Optical studies show the prominent blue shift in bandgap energy, whereas the Urbach energy decreases with the increased concentration x. The electrical conductivity of the films at room temperature is of the order of 10$^{–5}$ (${\Omega}$cm)$^{-1}$. The efficiency of the heterojunction cell structures Cd$_x$Pb$_{1–x}$S/CdTe and Cd$_x$Pb$_{1–x}$S/CdSe are calculated to be 3.37 and 2.21%, respectively.