فهرست مطالب a. a. yousefi

A hydrothermal method was used to synthesize different photoanodes for their application in dye-sensitized solar cells (DSSC). These photoanodes included WO3, TiO2, Graphene-TiO2, WO3-TiO2, and a nanostructure of Graphene-WO3-TiO2. The morphology of the nanoparticles was analyzed using the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-vis), and Fourier-transform infrared spectroscopy (FTIR). The results demonstrated that the graphene-WO3-TiO2 nanostructure had a large surface area, having provided more active sites for the efficient conversion of solar energy.  Notably, the DSSC incorporating the graphene-WO3-TiO2 nanoparticle electrode outperformed cells based solely on TiO2 and WO3, achieving a higher short-circuit current density of 7.5 mA.cm-2, an open-circuit voltage of 0.68 V, a fill factor of 0.46, and a power conversion efficiency of 2.4%. In contrast, the pure TiO2 and WO3 cells only achieved efficiencies of 0.88% and 0.69% Respectively.  The excellent electron mobility of the ternary nanostructure facilitated the charge trapping and injection into the conductive substrate, reducing recombination. Additionally, the scattering effect of the WO3 nanorods and graphene enhanced the light harvesting in the photoanode, leading to an increase in the overall efficiency of the solar cell. These findings highlight the potential of the synthesized graphene-WO3-TiO2 nanostructure as a promising photoanode material to be applied in DSSC.

In this investigation, the mechanical properties of the blends of blown bitumen110/10, heavy vacuum slops (H.V.S), bitumen 60/70 penetration grade and isotactic polypropylene (iPP) were studied for the first time. Our results showed that modulus varies non-linearly and at certain asphaltenes contents a peak appears. Considering these phenomena it is revealed that in the absence of iPP, interactions between the asphaltenes control the modulus of the blends. These interactions are dependent on the H.V.S and soft bitumen contents. The asphaltenes establish strong interactions with other asphaltene groups during dissolution in H.V.S or bitumen 60/70 (called solubility limit). At low percentges of iPP and high concentrations of asphaltenes a segregated network of asphaltenes is formed.Formation of this network increases the modulus of blends. At higher percentages of iPP and low asphaltenes concentration an interdiffusion-coalescence network is established. This network creates transition structures and increases the blend modulus. Finally, it is found that incorporation of iPP improves the modulus of bituminous blends.