Search

In this study, we employ first-principles calculations to explore the electronic and valleytronic properties of single-layer (SL) SMSiN2 (M = Mo, W), which are two-dimensional Janus materials with strong spin–orbit coupling. Our findings indicate that SL SMoSiN2/SWSiN2 possess a direct/indirect band gap, where the valence band maximum is situated at the K/K′ point, giving rise to the formation of degenerate valleys. When considering spin–orbit coupling, SMoSiN2 and SWSiN2 demonstrate intriguing valley spin splitting in their valleys, with a maximum splitting of up to 0.14/0.39 eV in the valence bands. By implementing magnetic doping with V and Cr, we provide a demonstration that valley polarization could be realized in SL SMSiN2. Moreover, the findings reveal high carrier mobility in SL SMSiN2, notably in SWSiN2, where hole carriers can achieve a remarkable mobility of up to 7.98 × 103 cm2 V−1 s−1 along the zigzag direction. Furthermore, our observations suggest that strain can be effectively utilized to manipulate the character and magnitude of the band gap, as well as the valley spin splitting in these materials. [ABSTRACT FROM AUTHOR]

Bioplastic bags mixed with food waste seem inevitable with the growth of waste classification and the banning of non-biodegradable polymers in China. To solve the asynchronous degradation of both food waste (FW) and bioplastics in the anaerobic digestion process, we investigated to determine the most effective pretreatment method. Among the three treatment options—physical, chemical, and biological—we found that biological pretreatment holds the most promise, primarily due to the efficient catalytic hydrolysis capacity of enzymes. We utilized three types of enzymes—amylases, lipases, and proteinase K—at a concentration of 0.075 g L−1 for pretreatment. The pretreatment process involved subjecting the FW/bioplastics mixture to enzymatic action for a duration of 48 h, at temperatures of 35 °C and 55 °C. We observed that the methane production from anaerobic digestion increased by 22.72%, 32.51%, and 60.95%, respectively, at the temperature of 55 °C when treated with the mentioned enzymes. Additionally, the degradation time of the bioplastic bags decreased from 30 to 24 days. Scanning electron microscopy (SEM) analysis revealed noticeable physical degradation, with the emergence of holes on the surface of the bioplastic following the enzymatic pretreatments and the effect of proteinase K was the most obvious. Further analysis using Fourier-transform infrared spectroscopy (FTIR) indicated that the peak observed at 1700 cm−1 is a characteristic peak of proteinase K depolymerization and the peak sign was significantly weakened after the experiment. This discovery suggests that proteinase K possesses a unique ability to break certain chemical bonds within bioplastics. Furthermore, novel bacterial species were identified in the substrate microbiome after proteinase K pretreatment. Notably, temperature was also a significant factor influencing material degradation. The enzymatic pretreatment enhanced biodegradation, resulting in enhanced methane yield during anaerobic digestion. These findings demonstrated the efficacy of biological pretreatment in effectively addressing the asynchronous degradation issue between food waste and bioplastics. [ABSTRACT FROM AUTHOR]

Hydrogen generation based on photocatalytic water splitting is a promising strategy for renewable energy production. Significant efforts have been made to improve the photocatalytic efficiency. However, the light harvesting ability of photocatalytic systems in the visible region still needs to be significantly improved to enable them to be a competitive technology for hydrogen generation. Herein, for the first time, we synthesized 2D Zn–Ag–In–S (ZAIS) nanosheets with strong absorption in the visible region and applied them for photocatalytic hydrogen generation. The exploration of oxygen passivation (O-ZAIS) reduced the defect concentration and nonradiative decay. The hydrogen generation rate is up to 25.2 mmol g−1 h−1, which is 14.7 times higher than that of pristine ZAIS nanosheets. Furthermore, by introducing 2D Co3O4 as the co-catalyst, carrier separation is accelerated, giving rise to a hydrogen generation efficiency of 43.6 mmol g−1 h−1. To the best of our knowledge, this is the highest efficiency reported among all kinds of 2D photocatalysts. [ABSTRACT FROM AUTHOR]

In this study, we employ first-principles calculations to explore the electronic and valleytronic properties of single-layer (SL) SMSiN 2 (M = Mo, W), which are two-dimensional Janus materials with strong spin-orbit coupling. Our findings indicate that SL SMoSiN 2 /SWSiN 2 possess a direct/indirect band gap, where the valence band maximum is situated at the K / K ' point, giving rise to the formation of degenerate valleys. When considering spin-orbit coupling, SMoSiN 2 and SWSiN 2 demonstrate intriguing valley spin splitting in their valleys, with a maximum splitting of up to 0.14/0.39 eV in the valence bands. By implementing magnetic doping with V and Cr, we provide a demonstration that valley polarization could be realized in SL SMSiN 2 . Moreover, the findings reveal high carrier mobility in SL SMSiN 2 , notably in SWSiN 2 , where hole carriers can achieve a remarkable mobility of up to 7.98 × 10 3 cm 2 V -1 s -1 along the zigzag direction. Furthermore, our observations suggest that strain can be effectively utilized to manipulate the character and magnitude of the band gap, as well as the valley spin splitting in these materials.