In this work, roll-graphene oxide (Ro-GO), polyaniline (PANI) nano/microparticles, and PbS nanoparticles were prepared by modified Hammer, oxidative polymerization, and chemical bath deposition methods, respectively. These nano/microstructures were characterized, optimized, and designed to form PbS/Ro-GO/PANI nano/microcomposite. Also, the ratios of PbS and Ro-GO were optimized, and the optimized composition of the used composite was 0.4 g PANI, 0.125 g Ro-GO, and 0.075 g PbS. The band gap values for PANI, PbS, Ro-GO, and PbS/Ro-GO/PANI rocomposite were 3, 1.13, 2.86, (1.16, 2) eV, respectively. Two photoelectrode assemblies, Au/PbS/Ro-GO/PANI and PbS/Ro-GO/PANI/ITO/glass were used for the photoelectrochemical (PEC) hydrogen generation. In the first assembly 45 nm- Au layer was sputtered on the surface of a disk of PbS/Ro-GO/PANI composite. For the second assembly, a disk of PbS/Ro-GO/PANI composite was glued on ITO glass using Ag-THF paste. The lifetime efficiency values were 64.2 and 43.4% for the first and second electrode for 2 h, respectively. Finally, the incident photon-to-current conversion efficiency (IPCE) and photon-to-current efficiency (ABPE) were calculated under monochromatic illumination conditions. The optimum IPCE efficiency at 390 nm was 9.4% and 16.17%, whereas ABPE % efficiency was 1.01% and 1.75% for Au/PbS/Ro-GO/PANI and PbS/Ro-GO/PANI/ITO/glass, respectively.

ITO/PEDOT:PSS/P3HT:PC₆₀BM/Mg-Al organic solar cells (OSCs) were fabricated depending on optimization of Poly(3-hexylthiophene-2,5-diyl) (P3HT) and phenyl-C61-Butyric-Acid-Methyl Ester (PC₆₀BM). The optimization of the active layer, P3HT:PC₆₀BM, was carried out under different spin frequencies coating from 900 to 3000 rpm. The post-production annealing temperature of all prepared OSC was studied from 130 to 190 °C. The holes transport layer, poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS), was prepared under constant conditions of 3000 rpm for 35 s, and annealing temperature 178 °C for 15 min. From our study, the optimum conditions for P3HT:PC₆₀BM were spin coating of 3000 rpm, and annealing temperature of 160 °C for 5 min. The optimum J-V parameters values for the prepared OSC were J_SC = 12.01 mA/cm², V_OC = 660 mV, FF = 59%, PCE = 4.65%, and EQE = 61%. A complete OSC with acceptable efficiency was designed using simple and low-cost techniques that may be utilized in the industry. Furthermore, the cost of the synthesized solar cell is projected to be around 1 $/cm², with the goal of lowering the cost and increasing efficiency in the future by incorporating more commercial nanostructured electron/hole transport components.

Graphitic carbon nitride (G-C3N4) was synthesized through the direct combustion of urea in the air. The CoS-Co₂O₃/G-C3N4 composite was synthesized via the hydrothermal method of G-C3N4 using cobalt salts. The morphological and chemical structures were determined through XRD, XPS, SEM, and TEM. XRD and XPS analyses confirmed the chemical structure, function groups, and elements percentage of the prepared nanocomposite. SEM measurements illustrated the formation of G-C3N4 sheets, as well as the flower shape of the CoS-Co₂O₃/G-C3N4 composite, evidenced through the formation of nano appendages over G-C3N4 sheets. TEM confirmed the 2D nanosheets of G-C3N4 with an average width and length of 80 nm and 170 nm, respectively. Two symmetric electrodes for the supercapacitor from the CoS-Co₂O₃/G-C3N4 composite. Electrochemical measurements were carried out to determine the charge/discharge, cyclic voltammetry, stability, and impedance of the prepared supercapacitor. The measurements were carried out under acid (0.5 M HCL) and basic (6.0 M NaOH) mediums. The charge and discharge lifetime values in the acid and base medium were 85 and 456 s, respectively. The cyclic voltammetry behavior was rectangular in a base medium for the pseudocapacitance feature. The supercapacitor had 100% stability retention up to 600 cycles; then, the stability decreased to 98.5% after 1000 cycles. The supercapacitor displayed a specific capacitance (C_S) of 361 and 92 F/g, and an energy density equal to 28.7 and 30.2 W h kg⁻¹ in the basic and acidic mediums, respectively. Our findings demonstrate the capabilities of supercapacitors to become an alternative solution to batteries, owing to their easy and low-cost manufacturing technique.

This work reports on H₂ fuel generation from sewage water using Cu/CuO nanoporous (NP) electrodes. This is a novel concept for converting contaminated water into H₂ fuel. The preparation of Cu/CuO NP was achieved using a simple thermal combustion process of Cu metallic foil at 550 °C for 1 h. The Cu/CuO surface consists of island-like structures, with an inter-distance of 100 nm. Each island has a highly porous surface with a pore diameter of about 250 nm. X-ray diffraction (XRD) confirmed the formation of monoclinic Cu/CuO NP material with a crystallite size of 89 nm. The prepared Cu/CuO photoelectrode was applied for H₂ generation from sewage water achieving an incident to photon conversion efficiency (IPCE) of 14.6%. Further, the effects of light intensity and wavelength on the photoelectrode performance were assessed. The current density (J_ph) value increased from 2.17 to 4.7 mA·cm⁻² upon raising the light power density from 50 to 100 mW·cm⁻². Moreover, the enthalpy (ΔH*) and entropy (ΔS*) values of Cu/CuO electrode were determined as 9.519 KJ mol⁻¹ and 180.4 JK⁻¹·mol⁻¹, respectively. The results obtained in the present study are very promising for solving the problem of energy in far regions by converting sewage water to H₂ fuel.