Synthesis and Characterization of TiO2 Semiconductor Doped by AgNO3 and Their Application as Photoanode in Dye-sensitized Solar Cells

The use of Titanium dioxide (TiO2) semiconductors in Dye-Sensitized Solar Cells (DSSC) devices have been extensively studied and synthesized with various techniques to obtain optimal performance. The TiO2 semiconductors with optimal performance are influenced by the growth method, the time of growth, the shape of the microstructure, and the optical properties. In this study, it was reported about the effect of silver nanoparticles (AgNO3) doping onto TiO2 semiconductors on their microstructure, reflectance, and efficiency of the DSSC device. The synthesis of TiO2 was carried out using liquid phase deposition (LPD) and immersed into an AgNO3 solution with a variation of time namely 0.5 h, 1 h, 2 h, 4 h, and 6 h. The entire TiO2 + AgNO3 sample, then used as a photoanode on DSSC with plastisol as a counter electrode. Characterization of microstructure, reflectance, and DSSC performance was carried out by using field emission scanning electron microscopy (FESEM), Uv-Vis Spectrophotometer, and Gamry Instrument, respectively. The FESEM results show that AgNO3 has successfully grown on the ITO substrate in a spherical shape with an average particle diameter ranging from 1.52-2.29 μm. From observations using the Uv-Vis Spectrophotometer, obtained the energy band gap values ranged from 0.22 to 2.27 eV. The best results of DSSC device efficiency, with TiO2+AgNO3/Dye/Plastisol structure, have resulted in the Voc of 0.694 V, current density (Jsc) of 0,943 mA/cm2and fill factor (FF) of 43,50% which is obtained at sample 1

Scalable Mesoporous Platinum Diselenide Nanosheet Synthesis in Water

Newly discovered two-dimensional (2D) atomic crystals (nanosheet) of platinum diselenide (PtSe₂) have progressively attracted attention due to their expected high performance in catalysis, sensing, electronics, and optoelectronics applications. Further extraordinary physicochemical properties are expected if these nanosheets of platinum diselenide can possess mesoporosity as this may enable a high range of molecular adsorption, enhancing their functionalities in catalysis, batteries, supercapacitors, and sensing. Here, we present for the first time a straightforward, aqueous-phase synthetic strategy for the preparation of scalable nanosheets of platinum diselenide with mesoporous structure via a surfactant-templated self-assembly followed by a thermal annealing phase-transformation process. We used hexamethylenetetramine as a hexagonal honeycomb (sp²–sp³ orbital) scaffold for assembling the Pt and Se organic complexes to form the nanosheet structure, which is stable, preserving the 2D structure and mesoporosity during a thermal annealing at 500 °C. Density functional theory analysis then indicated that the mesoporous nanosheets of platinum diselenide exhibit a high free-energy and large density of π electrons crossing the Fermi level, inferring a high-catalytic performance. This effortless strategy is currently being extended to the synthesis of other transition metal dichalcogenides, including the preparation of multi-metal atomic dichalcogenide nanosheets, for a wide variety of scientific and technological applications

Two-Dimensional, Hierarchical Ag-Doped TiO₂ Nanocatalysts: Effect of the Metal Oxidation State on the Photocatalytic Properties

This paper reports the synthesis of two-dimensional, hierarchical, porous, and (001)-faceted metal (Ag, Zn, and Al)-doped TiO₂ nanostructures (TNSs) and the study of their photocatalytic activity. Two-dimensional metal-doped TNSs were synthesized using the hydrolysis of ammonium hexafluorotitanate in the presence of hexamethylenetetramine and metal precursors. Typical morphology of metal-doped TNSs is a hierarchical nanosheet that is composed of randomly stacked nanocubes (dimensions of up to 5 μm and 200 nm in edge length and thickness, respectively) and has dominant (001) facets exposed. Raman analysis and X-ray photoelectron spectroscopy results indicated that the Ag doping, compared to Zn and Al, much improves the crystallinity degree and at the same time dramatically lowers the valence state binding energy of the TNS and provides an additional dopant oxidation state into the system for an enhanced electron-transfer process and surface reaction. These are assumed to enhance the photocatalytic of the TNS. In a model of photocatalytic reaction, that is, rhodamine B degradation, the AgTNS demonstrates a high photocatalytic activity by converting approximately 91% of rhodamine B within only 120 min, equivalent to a rate constant of 0.018 m^–1 and ToN and ToF of 94 and 1.57 min^–1, respectively, or 91.1 mmol mg^–1 W^–1 degradation when normalized to used light source intensity, which is approximately 2 times higher than the pristine TNS and several order higher when compared to Zn- and Al-doped TNSs. Improvement of the crystallinity degree, decrease in the defect density and the photogenerated electron and hole recombination, and increase of the oxygen vacancy in the AgTNS are found to be the key factors for the enhancement of the photocatalytic properties. This work provides a straightforward strategy for the preparation of high-energy (001) faceted, two-dimensional, hierarchical, and porous Ag-doped TNSs for potential use in photocatalysis and photoelectrochemical application

Ultra-thin MoS2 nanosheet for electron transport layer of perovskite solar cells

status: publishe

Synthesis of Amorphous Platinum Nanofibers Directly on an ITO Substrate and Its Heterogeneous Catalytic Hydrogenation Characterization

This paper reports a facile, solution-phase approach to synthesizing a one-dimensional amorphous face-centered-cubic (fcc) platinum (a-Pt) nanostructure (nanofibers) directly on an indium–tin oxide (ITO) substrate. The electron microscopy analysis result shows that the a-Pt nanofiber has a diameter and length of approximately 50 nm and 1 μm, respectively, and is grown in high density on the entire surface of the ITO substrate. The X-ray photoelectron spectroscopy analysis result further reveals that the a-Pt nanofibers feature metallic properties with highly reactive surface chemistry, promising novel performance in electrochemistry, catalysis, and sensors. A synergetic interplay between the formic acid reducing agent and the hexamethylenetetramine surfactant in the reduction of Pt ions is assumed as the driving force for the formation of the amorphous phase in the Pt nanostructure. The catalytic properties of a-Pt were examined in the acetone hydrogenation reaction under microwave irradiation. a-Pt shows excellent heterogeneous catalytic properties for converting acetone to isopropyl alcohol with turnover number and frequency as high as 400 and 140 min^–1, respectively. The preparation and formation mechanism of the a-Pt nanofibers will be discussed in detail in this paper

Enhancing the interfacial carrier dynamic in perovskite solar cells with an ultra-thin single-crystalline nanograss-like TiO2 electron transport layer

status: publishe