Effects Of Precursor Ratio Research Articles

Application of TiO2/gC3N4 for the efficient photosynthesis of hydrogen peroxide

Titanium dioxide/graphitic carbon nitride (TiO2/gC3N4) nanocomposite was successfully synthesized via the mixing of graphitic carbon nitride (gC3N4) with bulk titanium dioxide (TiO2) under sonication. The effect of precursor ratio on the morphological structure and photocatalytic hydrogen peroxide (H2O2) production performance was also investigated. According to the results, the TiO2 was successfully embedded and evenly distributed onto the structure of the gC3N4. Moreover, the as-prepared material with the TiO2 content of 20 % with respect to gC3N4 and catalyst dosage of 3 mg also possessed the greatest photocatalytic performance with an H2O2 production capacity of more than 3000 μM·g−1·h−1. Besides, the material also exhibited great recyclability, which remained at 70 % of the original performance after 5 consecutive reusing cycles. Following to the aforementioned results, the TiO2/gC3N4 nanocomposite can be considered a potential material for the photocatalytic production of H2O2.

A facile fabrication of zinc oxide‐doped carbon aerogel by cellulose extracted from coconut peat and sodium alginate for energy storage application

AbstractIn this study, ZnO‐doped carbon aerogel is synthesized from cellulose in coconut peat with sodium alginate as a binder via both freeze‐drying and pyrolysis processes. Of those, zinc nitrate is used as not only a crosslinking agent to form gel but also a precursor source to dope ZnO in the carbon aerogel matrix. The effect of precursor ratios on the characterization and energy storage capacity of composite aerogel is investigated. As a result, it is indicated that the formed ZnO‐doped carbon aerogel possesses a highly porous structure which is typical for aerogel structure shown by SEM images, density, and porosity. Besides, via the XRD patterns, the confirmation of the ZnO crystal structure is found within the carbon aerogel lattice. In terms of energy storage, based on the specific capacitance results, the ZCA‐4 sample with a sodium alginate and cellulose weight ratio of 1:20 shows the best energy storage with a specific capacitance of 105 F/g in the voltage range of 0–0.5 V and scan‐rate speed of 0.005 V. Therewithal, the ZCA‐4 also performs high durability, high scanning speed tolerance, and stable storage performance with efficiency reaching more than 99% after 500 consecutive scan cycles. These results demonstrate that the ZnO‐doped carbon aerogel has potential applications as electrode materials in supercapacitors.

Investigation of CsBr:BiBr3 precursor ratio concentration on cesium bismuth bromide perovskite formation

The effect of precursor ratios on the formation of Cs3Bi2Br9 via a re-precipitation synthesis method has been studied thoroughly. X-ray diffraction analysis showed that the precursor ratio was critical for the Cs3Bi2Br9 phase formation. The Cs-rich or Bi-rich precursor ratio resulted in diverse perovskite structure formation of Cs3BiBr6 and Cs3Bi2Br6 with micron size platelet and semi-micron size crystal morphology respectively. Unreacted BiBr3 precursor remains in the supernatant solution under Bi-rich conditions. The synthesized powder dispersed in toluene shows the degradation of the Cs3Bi2Br9 phase at Cs-rich conditions. Photoluminescence quantum yield (PLQY) of 0.73 % was identified in Cs3Bi2Br9 with a large contribution to the exciton-related recombination process. A precursor ratio CsBr:BiBr3 of 3.0:2.0 is proposed to form a single-phase Cs3Bi2Br9 structure, as the deviation in precursor ratio would promote the Cs3BiBr6 structure growth and affect the material’s optical performance.

Template synthesis of sulfur-doped mesoporous carbon for efficiently removing gas-phase elemental mercury from flue gas

Sulfur doped mesoporous carbon (SMC) was synthesized by using template method for efficiently removing gas-phase elemental mercury from flue gas. MCM-41 was used as sorbent template, and the mixture of thymol blue (C27H30O5S) and 2-thiophene ethanol (C6H8OS) was screened as co-precursor of carbon and sulfur. The mercury removal performance of the SMC was evaluated by fixed-bed mercury adsorption experiment. Effect of precursor ratio, carbonization temperature, adsorption temperature, and SO2 on mercury removal was studied. Combining with sorbent characterization, the mercury removal mechanism of the SMC was clarified. The results show that when the ratio of precursor (thymol blue: 2-thiophene ethanol) is 1:6 and the carbonization temperature is set at 900 ℃, the synthetic SMC-900 sorbent is a promising mercury sorbent, which displays excellent mercury removal performance as well as high SO2 tolerance. Decrease of carbonization temperature from 900 ℃ to 700 ℃ significantly reduces the mercury removal performance of SMC due to the incomplete carbonization of precursor. At 50–150 ℃, the mercury removal rate of SMC-900 is more than 97%, but a higher temperature inhibits its mercury removal capacity. The characterization result shows that the SMC-900 is spherical shape nanoparticle and the BET specific surface area reaches 933.0 m2/g. The mass proportions of carbon (C) and sulfur (S) of SMC-900 are 81.29% and 10.29%, respectively. The sulfur in SMC-900 is in the form of thiophene bond (C-S-C) and oxidized sulfur (C-SOx-C). In the presence of SO2, the main mercury removal product is HgS because the oxygen-containing functional group is occupied by SO2.

Effect of precursor ratio on the morphological and optical properties of CVD-grown monolayer MoS2 nanosheets

Atmosphere pressure chemical vapor deposition (CVD) is one of the most powerful methods of synthesizing high quality and large area MoS2 films with a reasonable cost. In our work, the large-scale and high crystalline quality monolayer MoS2 nanosheets were synthesized on Silicon substrate with a 300 nm oxide layer using MoO3 and S powders as precursors by an atmosphere pressure CVD. The results suggest that the surface morphology, crystalline quality and luminescence of CVD-grown MoS2 nanosheets can be tunable by controlling the precursor ratio (the effective Mo: S ratio). Excessive S-rich atmosphere is favor to synthesize large-size and high crystalline quality monolayer MoS2 nanosheets with sharp corners and straight edges. This study may provide insight into the synthesis of large-scale and high crystalline quality MoS2 films.

Effect of precursor ratios on the structural, morphological and optical properties of CBD-CdS films

Cadmium sulfide (CdS) films were deposited on fluorine doped tin oxide (FTO) glass substrates by chemical bath deposition (CBD). X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), photoluminescence (PL), and Fourier transform infrared (FT-IR) analyses were employed to compare the structural, morphological, and optical properties of deposited films. The XRD studies confirmed the cubic crystalline nature of the deposited films, and the intensities of the peaks were found to vary for different precursor ratios. The results of SEM study show that the films were smooth and uniform. The RMS surface roughness values of the CdS films were found to be in the range of 25.42nm to 35.33nm. Energy band-gap values of the CdS films were found in the range of 2.32eV to 2.39eV. Two distinct bands (centred at 489nm and 556nm) were found in the PL emission spectra. S-C-N, Cd-S, and C-S vibrations were observed to dominate in the FT-IR spectra.

One pot synthesis of stable water soluble thiol capped CdTe nanoparticles: Effect of precursor ratio, refluxing time and capping group on the optical property

Highly crystalline, monodispersed and stable water soluble thiol capped cadmium telluride nanoparticles (CdTe NPs) were synthesized via an environmental friendly, simple one-pot method in the absence of an inert atmosphere at constant pH. The effect of varying the precursor ratio and capping agent while keeping all other parameters constant, on the optical and structural properties of the as-synthesized nanocrystals was investigated. The optical and structural properties of the as-synthesized CdTe NPs was explored by using UV–visible (UV–Vis) absorption and photoluminescence (PL) spectroscopy, Fourier transform infra-red spectroscopy (FTIR) and transmission electron microscopy (TEM). Optical analysis shows that all the as-synthesized CdTe NPs possesses good optical properties with 1:0.8 ratio showing the highest absorbance and emission wavelength at different reaction time. The thiol capped water soluble CdTe NPs were optically stable at ambient conditions for several months.

Hardness Evaluation of Carbonate Apatite Cement Based on Various Ratio of Precursor

Carbonate Apatite (CO3Ap) cement is considered as an ideal bone substitute due to its biocompatibility and osteoconductivity. Also, CO3Ap cement has the chemical composition that closes to natural bone. During cement preparation, precursors play an important role that affects the properties of CO3Ap cement. Cement hardness is one of the important properties that need to be evaluated before the obtained cement can be applied as a bone substitute. Therefore, the purpose of this study is to determine the effect of precursor ratio of CaCO3 and CaHPO4 on the hardness level of CO3Ap cement. In the present study, the CO3Ap cement was prepared from CaCO3 and CaHPO4. Both Commercial and synthesized CaCO3 were used. The CO3Ap cement obtained from commercial CaCO3 was used as a control group. Synthesized CaCO3 was obtained from Indonesian natural limestone. Three different CaCO3:CaHPO4 ratios, 40:60, 30:70 and 20:80 were mixed with 1 mol/L Na2HPO4. Samples were kept at 37°C with 100% relative humidity for 24 hours then tested using micro Vickers hardness testing machine. The micro Vickers hardness of the control group with CaCO3:CaHPO4 ratio of 40:60, 30:70 and 20:80 were 5.09 VHN, 6.34 VHN, and 6.73 VHN, respectively. Meanwhile, the micro Vickers hardness of the CO3Ap cement obtained from synthesized CaCO3 were 6.22 VHN, 7.50 VHN, and 10.37 VHN for the CaCO3:CaHPO4 ratio of 40:60, 30:70 and 20:80, respectively. The micro Vickers hardness level of CO3Ap cement precursor ratio from the lowest to the highest was 40:60 < 30:70 < 20:80. In conclusion, the precursor ratio significantly affects the hardness level of the CO3Ap cement. The hardness level of CO3Ap cement obtained from synthesized CaCO3 was higher compared with that obtained from commercial CaCO3.

Effect of substrate temperature and precursor ratio on properties of thin ZnS films sprayed by improved method

Abstract Zinc sulphide (ZnS) thin films were prepared by improved spray pyrolysis (ISP) method. The ISP parameters, such as carrier gas flow rate, solution flow rate and substrate temperature, were controlled with an accuracy of ±0.25 lpm, ±1 ml/h and ±1 °C, respectively. The solution was sprayed in a pulsed mode. The substrate temperature was optimized by analyzing substrate temperature dependent properties of thin films. The thin film deposited at a temperature of 450 °C was dense and fairly smooth with satisfactory crystallinity and very small impurity content. The effect of precursor ratio in the solution on structural, compositional and optical properties of thin ZnS films, deposited at a temperature of 450 °C, was studied. A gradual increase in band gap energy from 3.524 eV to 3.634 eV, refractive index from 2.5 to 2.9 and dielectric constant from 6.6 to 8.7 were observed with the variation of solution precursor (Zn:S) ratio from (1:2) to (1:6). The structural and compositional studies support this kind of enhancement in optical properties. The results show that the thin ZnS film prepared by ISP at the substrate temperature of 450 °C from a solution with specific precursor ratio can be used for optoelectronic and photovoltaic applications.

Effect of Precursor Ratio on the Structural Properties of ZnO Thin Films Deposited by Low Pressure MOCVD

The effect of precursor ratio (H2O/DEZ) on the texture orientation, surface morphology, optical transparency and electrical resistivity of ZnO thin films deposited by MOCVD was investigated. Deposition temperature and pressure were fixed at 120 degrees C and 0.67 torr, respectively. The precursor ratio was varied between 0.1 and 4. It was found that the texture orientation changed from (0002) to (1120) with increase of the precursor ratio. (1120) textured film shows well facetted tetrapod like rough surface morphology, which scatters the incident light very effectively. The electrical resistivity was in the range of about 0.1 omega cm in the undoped state, which was found to decrease with increase of the film thickness and decrease of the precursor ratio.

Low-Temperature, Low-Pressure Chemical Vapor Deposition and Solid Phase Crystallization of Silicon–Germanium Films

Low-pressure chemical vapor deposition of silicon–germanium and its SPC below are investigated. The effects of precursor ratio [ ], pressure, and temperature are examined with the goals of film composition tunability and high deposition rates. is found to be a better source gas than DCS because the decomposition rate of is faster than that of DCS during the deposition process. In the system, the binary deposition mechanism is well explained by the “enhancement” model. The deposition temperature and chamber pressure affect the conversion factor, enabling independent tuning of the film composition and deposition rate. Amorphous and films are obtained at 350 and by adjusting the deposition conditions while keeping the deposition rates high. Compositional effects of the SiGe films on the SPC are also investigated.

Effect of Precursor Ratio on Synthesis and Optical Absorption of TiON Photocatalytic Nanoparticles

A simple sol–gel process was developed to synthesize a nitrogen‐doped titanium oxide (TiON) nanoparticle photocatalyst. Our work shows that the precursor ratio (tetramethyl ammonium hydroxide (TMA)/titanium tetraisopropoxide (TTIP)) has significant effects on the structure, composition, and optical properties of TiON nanoparticles. At high initial TMA/TTIP ratios, crystallization of the sol–gel TiON nanoparticle powders was sluggish, requiring a higher calcination temperature. As a high calcination temperature caused greater nitrogen loss, a high initial TMA/TTIP ratio in the TiON precursor did not ensure a high N/Ti atomic ratio in the TiON powders. By optimizing the initial TMA/TTIP ratio and the calcination temperature, crystalline powders were obtained with high nitrogen concentrations. These sol–gel TiON nanoparticles showed strong visible light absorbance.

Preparation of microencapsulated powders by an aerosol spray method and their optical properties

Abstract Microencapsulated powders were prepared by an aerosol spray method using a precursor comprised of a mixture of two types of sols as well as a sol-aqueous mixture precursor solution. Two different types of sols were used as precursors to prepare microencapsulated small-SiO 2/large-SiO 2 and Al 2O 3/SiO 2 powders. A microencapsulated ZrO 2/SiO 2 powder was also prepared from a mixture of SiO 2 sol and an aqueous precursor solution of zirconyl nitrate dihydrate. For preparing small-SiO 2/large-SiO 2 powders, two different sizes, i.e. 6 and 109 nm, of SiO 2 sols were used as precursors. The results show that the larger SiO 2 particles were encapsulated with the smaller ones. A similar result was also observed in the preparation of an Al 2O 3/SiO 2 powder prepared from a mixture of Al 2O 3 (18 nm) and a SiO 2 (109 nm) sol precursor. The Al 2O 3 particles appeared on the surface of the prepared powder. In the case of the ZrO 2/SiO 2 powder, the morphology indicates that the SiO 2 particles (109 nm) were encapsulated by a ZrO 2 shell. The effect of precursor ratios on the morphology of powders was also investigated. The light scattering characteristics of the prepared particles were also investigated using a laser particle counter coupled with a pulse height analyzer. The effective refractive indices of the microencapsulated powders varied considerably with the content of coating material.