Facile Microwave-assisted Approach Research Articles

A Facile Microwave-Assisted Nanoflower-to-Nanosphere Morphology Tuning of CuSe1–xTe1+x for Optoelectronic and Dielectric Applications

Transition metal chalcogenides have gained significant attention for their optoelectronic and electrical applications in various fields due to their elemental composition-dependent tunable properties. Here, a facile microwave-assisted approach was used to synthesize different CuSe1–xTe1+x-based nanomaterials. By varying the Se and Te concentrations, the morphology of CuSe1–xTe1+x was tuned from nanosheet-based flowers to nanospheres. With the increase in the value of the Te-to-Se content ratio, the material shows the transition from mixed nanosheets/nanospheres to pure nanospheres, where the average sheet thickness and sphere diameter are ∼25 and 80 nm, respectively. The as-synthesized material shows high crystallinity with mixed phases of hexagonal Cu2Te and CuSe. The chemical bonding of the material exhibits shifts of the spectra toward lower binding energies with the decrease in the Se-to-Te ratio. The material exhibits a change in the absorption edge with a blue shift of the optical bandgap for the increase of the Te content. The increment in the absorption makes them eligible for solar cell application. The photoluminescence spectra of different CuSeTe samples show broad emission in the 550–950 nm range with a peak at ∼700 nm. Such optical properties enable CuSeTe materials for possible applications in optoelectronic devices. The dielectric measurement of the sample exhibits an increase in the dielectric constant and loss with temperature, whereas a decrease in both the values is apparent for increase in the frequency. The dielectric study of the material reveals its potential application for energy storage. The photo-response study demonstrated that the material can be employed for photodetector application.

Dual cocatalyst modified CdS achieving enhanced photocatalytic H2 generation and benzylamine oxidation performance

Cocatalyst can greatly facilitate the charge separation efficiency and decrease the activation barrier of a specific reaction, thus contributing the improved photocatalytic performance. Herein, PdS/CdS/MoS2 was synthesized via a facile microwave-assisted approach. Owing to the coexistence of PdS and MoS2, respectively serving as oxidation and reduction cocatalyst, PdS/CdS/MoS2 displayed enhanced photocatalytic performance in both hydrogen production (6610 μmol·g−1·h−1) and benzylamine oxidation (87% conversion) in comparison with the individual and binary composite counterparts. The improved photocatalytic activity was mainly attributed to the high charge separation efficiency and lowed activation barrier. Furthermore, the introduction of PdS can timely extract photogenerated holes from CdS, which effectively inhibits the photo-corrosion of CdS, endowing it with high stability. This work paves the way for developing efficient chalcogenide photocatalysts.

Plasmonic composites WO3/Bi12O17Cl2 decorated with uniform Ag nanoparticles in tiny size: Synthesis, analyses, and visible-light photocatalytic performance

Various novel ternary composites Ag/WO3/Bi12O17Cl2 were successfully constructed through a rapid and facile microwave-assisted approach to decorate Ag nanoparticles onto WO3/Bi12O17Cl2 surface. Through analyses, three expected components were coexisted and formed n–p heterojunctions with Ag nanoparticles of uniform morphology and size below 20 nm. These plasmonic composites with favorable physiochemical properties showed greatly reinforced photocatalytic performance over degradation of Rhodamine B (RhB), methyl orange (MO), and tetracycline hydrochloride (TC) upon visible light irradiation. Moreover, these samples exhibited satisfactory structural stability and reusability in both aqueous and saline solution. Eventually, a plausible photocatalysis mechanism was speculated upon analytical and experimental results. Such investigation might provide a series of ternary composites with small size of Ag nanoparticles for sake of contaminants control and environmental preservation.

Temperature- and humidity-sensing properties of ZnO:Yb/Er nanocrystal clusters synthesized by a facile microwave-assisted approach

In this paper, we synthesized monodispersed ZnO:Yb/Er nanocrystal clusters (NCs) by a facile microwave-assisted approach. The fluorescence intensity ratio technique based on the two green upconversion emissions of ZnO:Yb/Er NCs was studied as a function of temperature with the maximum temperature sensitivity of 0.00323K−1 in the range of 300–625K. The ZnO:Yb/Er NCs also exhibited excellent impedance-dependent humidity sensing behavior with fast response and recovery characteristics time and dynamic response at a wide range of 11–95% relative humidity. It is anticipated that the present rare-earth doped ZnO NCs can furnish a simple, inexpensive and facile multifunctional application both in temperature and humidity sensing.

Enhanced performance in inverted polymer solar cells employing microwave-annealed sol-gel ZnO as electron transport layers

In this work, we propose a facile microwave-assisted approach for annealing sol-gel derived ZnO films to serve as electron transport layers (ETLs) for inverted bulk heterojunction polymer solar cells. We have demonstrated an impressive enhancement in performance for devices based on a poly (3-hexylthiophene) (P3HT): (6,6)-phenyl-C61-butyric acid methyl ester (PC61BM) system employing the microwave-annealed ZnO (ZnO (MW)) ETLs in comparison to the cases using the conventional hotplate-annealed ZnO (ZnO (HP)) ones. The better electron transport in the device with the ZnO (MW) ETL is mainly ascribed to the preferable interfacial contact as evidenced by the morphology characteristics. Furthermore, the comprehensive analyses conducted from the light intensity dependent photocurrent and photovoltage measurements, the capacitance-voltage characteristics, and the alternating current impedance spectra suggest that the utilization of the ZnO (MW) ETLs can effectively suppress trap-assisted recombination as well as charge accumulation at the interface between P3HT: PC61BM layers and ZnO layers, which is responsible for the enhanced device performance.

Enhanced BTEX gas-sensing performance of CuO/SnO2 composite

Series CuO/SnO2 composites for selectively sensing BTEX (benzene, toluene, ethylbenzene, and xylol) designed by a principle of catalytic oxidation were synthesized. The sensing materials were prepared by a facile microwave-assisted approach. The composites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). TEM results reveal that the as-prepared SnO2 are nanoscaled porous particles. For 3mol% CuO/SnO2 composite, the existence of CuO nanoparticles is proved by EDS and HRTEM. Gas sensing results of side-heating sensors display that the CuO/SnO2 composites sensors compared with pristine SnO2 sensor have much better responses to BTEX rather than other VOCs such as ethanol, acetone, methanol, formaldehyde and ammonia. Among these CuO/SnO2 composites, the sensor based on 3mol% CuO/SnO2 composite has the best selectivity and sensitivity for BTEX. At the optimal working temperature of 280°C, the response value of the sensor to 50ppm BTEX are more than 6 times. Excellent gas sensitive performance of 3mol% CuO/SnO2 based sensor to BTEX belongs to the addition of catalyst CuO.

CuO nanoparticles on sulfur-doped graphene for nonenzymatic glucose sensing

This study reports a novel CuO nanoparticles (NPs) supported on S-doped graphene (CuO/SG) as an electrode material for nonenzymatic glucose detection. The CuO/SG was successfully synthesized by a facile microwave-assisted approach, and CuO/SG composed of ∼13nm of CuO NPs being relatively well-distributed and strongly anchored on SG was obtained. Electrochemical test revealed that the CuO/SG based electrode exhibited a higher electrocatalytic activity toward glucose oxidation than CuO NPs and CuO/reduced graphene oxide (rGO) modified electrodes owing to the synergistic effect between CuO NPs and SG. As a consequence, the CuO/SG based sensor exhibited a rapid response of 2s, a wide linear range of 0.1–10.5mM, a high sensitivity of 1298.6μA·mM−1·cm−2, and a low detection limit of 80nM, along with the excellent selectivity, high stability, and good accuracy in real sample analysis, thus leading to a promising candidate for nonenzymatic glucose detection.

Electrochemical activity and stability of Pt catalysts on carbon nanotube/carbon paper composite electrodes

This article reports a facile microwave-assisted approach to synthesize Pt catalysts on carbon nanotube (CNT)/carbon paper (CP) composite through catalytic chemical vapor deposition. The Pt deposits, with an average size of 3–5 nm were uniformly coated over the surface of oxidized CNTs. The electrochemical activity and stability of the Pt–CNT/CP electrode were investigated in 1 M H 2SO 4 using cyclic voltammetry (CV) and ac electrochemical impedance spectroscopy. The Pt catalysts showed not only fairly good electrochemical activity (electrochemically active surface area) but also durability after a potential cycling of >1000 cycles. The analysis of ac impedance spectra associated with equivalent circuit revealed that the presence of CNTs significantly reduced both connect and charge transfer resistances, leading to a low equivalent series resistance ˜0.22 Ω. With the aid of CNTs, well-dispersed Pt catalysts enable the reversibly rapid redox kinetic since electron transport efficiently passes through a one-dimensional pathway. Thus, the CNTs do not only serve as carbon support, they also charge transfer media between the Pt catalysts and the gas diffusion layer. The results shed some light on the use of CNT/CP composite, offering a promising tool for evaluating high-performance gas diffusion electrodes.