Sharif Digital Repository

Abstract We report the well-controlled preparation of WS2 nanosheets-CdS nanoparticle heterojunction for photoelectrochemical (PEC) water splitting application. The WS2 nanosheets with an average thickness of ~5 nm and lateral dimensions of ~200 nm were synthesized via liquid phase exfoliation of bulk WS2 in water/ethanol solution, followed by deposition onto ITO substrate via electrophoretic method. CdS nanoparticles were grown via facile successive ion layer absorption and reaction (SILAR) method. Using these two well-controlled methods, CdS/WS2/ITO and WS2/CdS/ITO systems were fabricated. The loading of WS2 nanosheets was... 

The Multi-walled carbon nanotube (MWCNT)/WO3 nanocomposite thin films with different MWCNT's weight percentages were prepared by sol-gel method as visible light induced photoanode in water splitting reaction. Weight percentage of MWCNT in the all nanocomposite thin films was confirmed by TGA/DSC analysis. According to XPS analysis, oxygenated groups at the surface of the MWCNT and stoichiometric formation of WO3 thin films were determined, while the crystalline structure of the nanocomposite samples was studied by XRD indicating (0 0 2) peak of MWCNT in the monoclinic phase of WO3. The influence of different weight percentage (wt%) of MWCNT on WO3 photoactivity showed that the electron... 

Copper sulfide deposited ZnO nanorods (ZnO NRs/CuS) have been applied as a new counter electrode material with high electrocatalytic activity towards polysulfide electrolyte, which results in the formation of a highly efficient counter electrode for QDSSCs. It was observed from the current density-voltage (J-V) characteristics that the short-circuit current density (Jsc), power conversion efficiency (PCE), and fill factor (FF) were enhanced from 7.63 mA cm-2 to 14.48 mA cm-2, 1.59% to 4.18%, and 0.29 to 0.38, respectively, when a bare CuS counter electrode was changed to a ZnO NRs/CuS counter electrode. Electrochemical impedance spectroscopy (EIS), Tafel polarization and cyclic voltammetry... 

Herein, we report the impact of light scattering mechanism on photovoltaic and photoelectrochemical performance of dye-sensitized solar cell (DSC) devices composed of TiO2 nanoparticles and hollow cubes. DSCs are designed by two different light scattering modes (i.e., mode I in form of single layer electrode containing nanoparticles and hollow cubes and mode II in the form of double layer electrode comprising active and scattering layers made of nanoparticles and mixtures of nanoparticles and hollow cubes, respectively). The synthesized anatase-TiO2 hollow cubes (200–400 nm) and nanoparticles (15–30 nm) are employed to enhance the optical length and light harvesting of photoanodes,... 

TiO2 nanotube arrays (TNA) have been modified by cobalt phosphate (CoPi) through potentiostatic electrodeposition method. Different samples have been prepared by changing the loaded CoPi through the deposition time from 10 to 960 min. Formed catalytic materials have been characterized by different methods. Although charge transfer resistance of the CoPi/TNA photoanodes have been decreased from 5.5 to 4.0 kΩ by increasing the deposition time from 5 to 60 min, the maximum photoresponse was obtained for 10 min CoPi deposition leading to 24% more photocurrent compare to bare TNA which proposed optimum value for cobalt phosphate decoration. Based on field emission scanning electron microscopy... 

TiO2 is a promising photoanode material for photoelectrochemical (PEC) water splitting, but its severe bulk recombination of photogenerated carriers, sluggish oxygen evolution reaction (OER) kinetics and poor visible light response are the main bottleneck problems. Here, the carbon quantum dots (CQDs) modified anatase/rutile TiO2 photoanode (CQDs/A/R-TiO2) was designed by growth of anatase TiO2 nanothorns on rutile TiO2 nanorods and further surface modification of CQDs. The results revealed that the A/R-TiO2 heterojunction significantly suppressed the bulk recombination of photogenerated carriers. With further incorporation of CQDs into A/R-TiO2, dramatical improvement of OER kinetics and... 

Enhancing stability against photocorrosion and improving photocurrent response are the main challenges toward the development of cupric oxide (CuO) based photocathodes for solar-driven hydrogen production. In this paper, stable and efficient CuO-photocathodes have been developed using in situ materials engineering and through gold-palladium (Au-Pd) nanoparticles deposition on the CuO surface. The CuO photocathode exhibits a photocurrent generation of ∼3 mA/cm2 at 0 V v/s RHE. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis and X-ray spectroscopy (XPS) confirm the formation of oxygen-rich (O-rich) CuO film which demonstrates a highly stable photocathode with retained...