Enhanced Tetracycline Adsorption of MoS2 via Defect Introduction Under Microwave Irradiation.

Defect engineering is a promising method for improving the performance of MoS2 in various fields. In this study, sulfur-defect-enriched MoS2 (SD-MoS2) nanosheets were fabricated via a facile microwave-hydrothermal strategy in 10 min for tetracycline (TC) adsorption applications. The introduction of sulfur defects in MoS2 induced more exposed unsaturated sulfur atoms at the edge, enhancing the interaction between the adsorbent and antibiotic and improving the adsorption activity of the antibiotic. Density functional theory calculations further revealed that sulfur defects in MoS2 could alter the electronic structure and exhibited low TC adsorption energy of -2.09 eV. This work provides a new method for fabricating MoS2 nanosheets and other transition metal dichalcogenide-based adsorbents with enhanced antibiotic removal performance and a comprehensive understanding of antibiotic removal mechanisms in SD-MoS2.

Facile One-step Production of 2D/2D ZnO/rGO Nanocomposites under Microwave Irradiation for Photocatalytic Removal of Tetracycline.

Antibiotic wastewater poses a great threat to the ecological environment and human health. Photocatalytic technology is an effective way to solve environmental pollution problems. In recent years, 2D/2D nanocomposites have received widespread attention because of their larger contact area, which can improve photocatalytic activity. However, the rapid synthesis of 2D/2D nanocomposites at low temperatures is still a challenge. Here, we demonstrated a facile one-step approach to synthesize 2D/2D ZnO nanosheet/rGO nanocomposites through microwave heating in a short time (20 min) for photodegradation of tetracycline (TC). Compared to the pure ZnO nanosheets, the ZnO/rGO-2 nanocomposites exhibited best photocatalytic activity under UV light. The enhanced photocatalytic performance could be attributed to introduction of GO nanosheets, which improves the specific surface area and pore structure and enhances the TC adsorption capacity. In addition, due to the interfacial coupling between ZnO and rGO, the charge was rapidly transferred and the recombination of photogenerated electron-hole pairs on the ZnO surface was inhibited. Our present work provided an efficient and low-temperature strategy for designing 2D/2D ZnO nanosheet/rGO photocatalysts and achieved gram-level production, which opens a new path to fabricate 2D/2D nanocomposites using microwave technology.

Fabrication of MoS2 QDs/ZnO nanosheet 0D/2D heterojunction photocatalysts for organic dyes and gaseous heavy metal removal.

In this paper, a novel 0D/2D heterojunction photocatalyst based on MoS2 QDs/ZnO nanosheets was successfully constructed by a simple two-step process, and its photocatalytic behavior for organic dyes (RhB) degradation and gaseous heavy metals (Hg) removal under ultraviolet light were studied. For the optimum 5% MoS2/ZnO photocatalyst, 95% of RhB could be removed in 50 min, and 99.8% of the gaseous mercury could be removed in 60 min. Besides, MoS2 QDs/ZnO nanosheets also exhibited excellent photocatalytic durability. The constructed 0D/2D heterojunctions could efficiently improve the separation efficiency and charge transfer of photogenerated carriers, thus improving the photocatalytic activity. Therefore, this strategy provided a new way to design bifunctional 0D/2D heterojunction photocatalysts for water treatment and air pollution.

Dielectric Properties of Silicothermic Reduction Chromite in the Microwave Field.

The microwave absorption properties of chromite and the feasibility of microwave reduction chromite have been discussed. The results show that as the density increases, the dielectric properties of materials increase. The dielectric properties are the best (the value around 4.2) when the silica ratio is 0.5. Microwave penetration depth shows that chromite and the mixture have good wave absorption properties.

Efficient Preparation of Si3N4 by Microwave Treatment of Solar-Grade Waste Silicon Powder.

In this study, the waste silicon powder generated in the production of solar-grade polysilicon scrap was used as the raw material, and silicon nitride (Si3N4) was directly efficient prepared by the microwave heating nitridation. The temperature raising characteristics of silicon powder by microwave heating and the influencing factors of the nitridation reaction process were studied. The thermogravimetric analysis was performed, and the temperature raising dielectric properties of silicon powder were studied. The electromagnetic field and temperature distributions of the microwave heating-induced silicon powder nitridation process were simulated using COMSOL software. The nitridation reaction of silicon powder induced by microwave heating has better temperature raising characteristics: the average heating rate can reach 135 °C/min, and the reaction time is significantly shortened (only 10-20 min). Microwave heating decreases the nitridation reaction temperature by more than 100 °C and greatly shortens the reaction time. With the increase of nitrogen pressure and reaction time, the nitridation reaction is better. In addition, the conversion of the nitridation reaction is more than 97%, and the products are mainly ß-Si3N4 with the uniform and columnar morphology. Finally, it is proved that the efficient recovery and utilization of industrial waste silicon powder are realized, and there is lower energy consumption by microwave heating technology.