Properties Study of SILAR Deposited Cobalt Selenide Thin Films

Thin films are attractive materials to be used in laser, solar cells, sensors, phosphors, light emitting diodes, IR windows and flat panel displays. Several deposition methods have been employed to deposit thin films as reported by many researchers. In this report, the cobalt selenide thin films have been deposited onto microscope glass slide via successive ionic layer adsorption and reaction method. This deposition method is a simple method owing to the inexpensive technique and can produce films at a low bath temperature. All the samples were investigated by using XRD, FESEM and UV-visible spectrophotometer. The XRD pattern confirmed that cubic phase cobalt selenide thin films. The FESEM image exhibited that the obtained sample is dense, uniform, and smooth surface. Keywords: XRD, FESEM, Thin films, Cobalt selenide, SILAR technique, Semiconductor, Band gap.

Simple Fabrication of BiVO4 Thin Films Synthesized by Modified SILAR Method: Effect of Film Thickness

In this study, BiVO4 photoanodes were synthesized using a simple and inexpensive modified successive ionic layer adsorption and reaction (SILAR) method. In particular, the effect of the number of SILAR cycles on the photoelectrochemical (PEC) properties of BiVO4 was evaluated. Scanning electron microscopy analysis revealed the porous surface morphology of the BiVO4 thin layers with irregularly shaped particles formed on the surface of fluorine-doped tin oxide substrates. The crystal structure of BiVO4 was confirmed using X-ray diffraction analysis. The ultraviolet–visible spectrophotometry results indicated that the bandgap energy of the deposited film was approximately 2.4 eV. In addition, the PEC properties of the BiVO4 photoanodes using potentiostat were analyzed. The linear sweep voltammetry curves revealed that the photocurrent density of the BiVO4 samples increased with the increasing number of m-SILAR cycles, and a maximum photocurrent density of approximately 0.83 mA/cm2 was achieved for the BVO-35. These results suggest that an efficient photoelectrode for compact PEC cells can serve as a basis for development.

Enhanced Catalytic Activities of TiO2 Nanotube Arrays Co-Sensitized with Pt/CdS/ZnS via Electrodeposition and Successive Ionic Layer Adsorption and Reaction (SILAR) Method Approach

In this work, we have synthesized a nanocomposite ZnS/CdS/Pt/TiO2 nanotube arrays (denoted ZCP-NTAs). Firstly, TiO2 nanotube array (NTAs) material was fabricated by the anodic method of a titanium plate in an electrolyte solution containing 0.35 M NaHSO4 and 0.24 M NaF and incubated in the air at 500 ºC for 2 hours. After that, pulsed electrodeposition technology was used to decorate platinum nanoparticles (denoted as Pt NPs) onto the surface of TiO2 nanotubes to form P-NTAs photoelectrodes. Then, the SILAR method is used to deposition CdS quantum dots (symbolized as CdS QDs) on the surface of P-NTAs to form CP-NTAs material. Finally, by the SILAR method, a ZnS passive layer that protects against optical corrosion and inhibits recombination of e−/h+ pairs was coated onto the CP-NTAs to form ZCP-NTAs material. As-prepared ZCP-NTAs photocatalytic material has good absorbability of light in the visible region with light absorption wavelength up to 608 nm, photon conversion efficiency up to 5.32% under light intensity AM1.5G, and decomposition efficiency of 10 mg L−1 methyl orange (MO) in 120 minutes reached 91.50%. This material promises to bring high application ability in the photocatalytic field applied for environmental treatment and other applications.

Cds nanocrystal enhanced TiO2photoelectrochemical aptasensor for sensitive detection of cytochrome c

A CdS nanocrystal enhanced TiO2 nanotubes (CdS@TiO2 NATs) photoelectrode was prepared via successive ionic layer adsorption and reaction (SILAR) of CdS on the surface of TiO2 NATs. A HS-aptamer owing a specific binding toward cytochrome c was modified onto the CdS@TiO2 NATs, which resulting a decrease in the photoelectrical current intensity. Cytochrome c is therefore quantified based on the decrease in photoelectrical current. High specificity and high sensitivity were obtained with a linear range from 3 pM to 80 nM, and a limit of detection of 2.53 pM.

Study of Green Seaweed Biochar for Lead Adsorption from Aqueous Solution

The current work used a batch study to investigate the efficiency of Ulva lactuca carbon for lead adsorption from aqueous solution. For the optimization study, the effects of several parameters such as pH, Adsorbent dosage, effective contact time, and initial concentration on lead removal were also considered. pH 3 was observed to be the most beneficial. The Langmuir isotherm, which represents mono-layer adsorption, yielded a maximum lead absorption of 3.49 mg/g. SEM was used to examine surface adsorption behavior, and FTIR was used to detect probable functional groups involved in the bio-adsorption experiment. This study shows that biochar made from the marine algae Ulva lactuca is effective for waste water treatment.

Adsorption Performance of Amino Functionalized Magnetic Molecular Sieve Adsorbent for Effective Removal of Lead Ion from Aqueous Solution

Lead ion (Pb2+) has high toxicity and brings great harm to human body. It is very important to find an effective method to address lead ion pollution. In this work, amino functionalized CoFe2O4/SBA–15 nanocomposite (NH2–CoFe2O4/SBA–15) was prepared for the effective removal of Pb2+ from aqueous solution. The prepared NH2–CoFe2O4/SBA–15 adsorbent was manifested by using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectrum (FTIR), X-ray powder diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. In the meantime, the adsorption conditions, including pH, adsorbent dosage, and adsorption time, were studied. The investigation of adsorption kinetics revealed that the adsorption results conform to the pseudo-first-order kinetic model. The adsorption isotherms research displayed that the adsorption was consistent with the Freundlich model, demonstrating that the adsorption for Pb2+ with the prepared adsorbent was a multimolecular layer adsorption process. In addition, the thermodynamic investigations (ΔG < 0, ΔH > 0, ΔS > 0) demonstrated that the adsorption for Pb2+ with the prepared adsorbent was endothermic and spontaneous. Moreover, the prepared adsorbent showed superior anti-interference performance and reusability, implying the potential application of the adsorbent in actual water treatment. Furthermore, this research may provide a reference and basis for the study of other heavy metal ions.

Effect of Morphology and Plasmonic on Au/ZnO Films for Efficient Photoelectrochemical Water Splitting

To improve photoelectrochemical (PEC) water splitting, various ZnO nanostructures (nanorods (NRs), nanodiscs (NDs), NRs/NDs, and ZnO NRs decorated with gold nanoparticles) have been manufactured. The pure ZnO nanostructures have been synthesized using the successive ionic-layer adsorption and reaction (SILAR) combined with the chemical bath deposition (CBD) process at various deposition times. The structural, chemical composition, nanomorphological, and optical characteristics have been examined by various techniques. The SEM analysis shows that by varying the deposition time of CBD from 2 to 12 h, the morphology of ZnO nanostructures changed from NRs to NDs. All samples exhibit hexagonal phase wurtzite ZnO with polycrystalline nature and preferred orientation alongside (002). The crystallite size along (002) decreased from approximately 79 to 77 nm as deposition time increased from 2 to 12 h. The bandgap of ZnO NRs was tuned from 3.19 to 2.07 eV after optimizing the DC sputtering time of gold to 4 min. Via regulated time-dependent ZnO growth and Au sputtering time, the PEC performance of the nanostructures was optimized. Among the studied ZnO nanostructures, the highest photocurrent density (Jph) was obtained for the 2 h ZnO NRs. As compared with ZnO NRs, the Jph (7.7 mA/cm2) of 4 min Au/ZnO NRs is around 50 times greater. The maximum values of both IPCE and ABPE are 14.2% and 2.05% at 490 nm, which is closed to surface plasmon absorption for Au NPs. There are several essential approaches to improve PEC efficiency by including Au NPs into ZnO NRs, including increasing visible light absorption and minority carrier absorption, boosting photochemical stability, and accelerating electron transport from ZnO NRs to electrolyte carriers.

Effect of pH on the Synthesis of Cobalt Selenide Films by SILAR Method

The successive ionic layer adsorption and reaction method or called SILAR method was used to produce cobalt selenide thin films for the first time. The deposition was carried out onto the substrate under different various pH values. The X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and ultraviolet visible spectrophotometer were used to investigate the structure, morphology and optical properties of thin films, respectively. The XRD patterns confirmed that the presence of cubic phase cobalt selenide thin films. The grain size increased with increasing the pH value from pH 2 to pH 4 based on the FESEM images. The band gap values are in the range of 2 eV to 2.5 eV.