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The cathode with low-energy consumption and long-term stability is pivotal to achieve the conversion of nitrate (NO

The internal Fe2+/Fe3+ cycle is important for peroxymonosulfate (PMS) activation by iron-based materials to produce the reactive oxidative species (ROS) for the breakdown of organic contaminants. Previous studies have focused on the contribution of heterogeneous sulfur species to the Fe2+/Fe3+ cycle such as lattice S(-II) and surface SO32– of iron sulfides. In this study, we found that the dissolved S(-II) from mackinawite (FeS) had a substantial contribution to the Fe2+/Fe3+ cycle. Furthermore, the oxidation intermediates of the dissolved S(-II) such as S2O32− and SO32− ions could convert Fe3+ to Fe2+ in solution. The elimination of target organic pollutant bisphenol A (BPA) derived from PMS activation triggered by the dissolved Fe2+ might be enhanced by the equivalent dissolved S(-II) in the FeS/PMS system. These results revealed that previous studies underestimated the significance of PMS activation by dissolved Fe2+ of iron sulfides to organic pollutant degradation. Moreover, SO4•- and •OH were more likely to be the main ROS for BPA degradation in the FeS/PMS system compared with FeO2+. Considering that the metal sulfides have been widely used to activate PMS, H2O2 and peroxydisulfate, this study offers a new perspective on the function of sulfur in these advanced oxidation processes.

Carbonaceous material is not only the excellent adsorbent for organic contaminants removal, but also the effective activator for peroxydisulfate (PDS) activation. In this study, a nitrogen-doped hierarchical porous carbon material (NHGBC-800) presented the attractive bifunctional properties was developed for the removal of model organic contaminant antibiotic tetracycline (TC). On the one aspect, the NHGBC-800 had a large specific surface area (1178.0 m2/g) and achieved good TC removal with a maximal adsorption capacity (Qm) of 629.76 mg/g at 303 K. On the other aspect, TC-saturated NHGBC-800 could effectively activate PDS with itself as the activator, by which the mineralization of desorbed TC and in-situ regeneration of exhausted adsorbent were achieved simultaneously. The Qm of NHGBC-800 recovered 90.61% after first regeneration and still retained 77.18% even after the 6th adsorption-regeneration cycles. Moreover, the as-prepared material maintained good adsorption and regeneration performance under a wide range of pH conditions (3.02–9.83) and in the presence of inorganic anions such as Cl−, SO42−, NO3−, H2PO4−, HCO3−. The electro spin resonance (ESR), reactive oxygen species (ROS) quenching studies and electrochemical measurement revealed that the electron-transfer and single oxygen mediated the non-radical pathways dominated the TC degradation during the regeneration process. Compared with the conventional thermal and electrochemical regenerations, the in-situ regeneration of bifunctional carbon materials induced by PDS activation is more effective, sustainable and environmental-friendly.

Perovskite nanocrystals (PNCs) have emerged as highly promising optical gain materials for laser applications. Despite the recent surge of reports on their lasing performance, it remains a challenge to achieve PNCs-based single-mode vertical cavity surface emitting lasers (VCSELs) because of their inhomogeneous gain saturation. Here, we successfully demonstrate high performance single-mode VCSELs using CsPbBr3 PNCs that were synthesized via a facile ligand-assisted reprecipitation strategy. The optical gain medium with wide crystal size range was fabricated, and the dense assembly of each individual PNCs was expected to offer a homogeneous optical continuum to reduce gain saturation inhomogeneity. The fabricated VCSELs exhibit excellent single-mode lasing at ~541 nm without mode hopping and high spontaneous emission coupling factor of ~0.24, which is one order of magnitude higher than those of nitride-based VCSELs. Through streak camera direct observations, the stimulated emission of the laser device exhibits an ultrafast decay of ~10 ps, and the electron hole plasma (EHP) mechanism is considered responsible for stimulated emission in the VCSELs. This work paves the way toward next-generation high performance PNC-based single-mode laser devices with reduced fabrication cost for practical application.

Allicin as an active component in allium species being widely present in food waste (FW) and waste activated sludge (WAS). Recently, allicin has been found to inhibit the anaerobic co-digestion. However, few literatures were available related to its impacting on organic matter release and microbial community in anaerobic co-digestion system of FW and WAS. Thus, this work aimed to fill that gap through use a series of batch test under conditions of pH 7 and 35 ± 1 °C. Experimental results showed that the anaerobic co-digestion system almost could not measure methane accumulation before day 20, when allicin dosage was 2.0 μg/L. However, the amount of intracellular material released from FW and WAS to substrate liquid was raised, including organic matter, PO43−-P and NH4+-N. Analysis of microbial community based on high throughput sequencing showed that microbial diversity increased at initial phase of anaerobic co-digestion from FW and WAS, meanwhile, community abundance of Candidatus_Methanofastidiosum raised significantly with co-digestion time. Whereas, methanosaeta abundance was only 19.74% in the allicin test reactor that it was the highest abundance in blank group.

The enhancement of zerovalent iron (ZVI) on anaerobic digestion (AD) has been proved, but there are still some problems that constrain the large-scale application of ZVI, such as the destruction of cell membrane and the inhibition of methanogenesis led by rapid H2 accumulation. Aiming at these problems, sulfidated microscale zerovalent iron (S-mZVI) was employed to evaluate its effect on anaerobic co-digestion (AcoD) of waste activated sludge (WAS) and food waste (FW). Experimental results showed that S-mZVI promoted the direct interspecies electron transfer (DIET) between specific bacteria and methanogens, resulting in higher methane yield. At S-mZVI 10 g/L, the cumulative methane yield and ETS activity reached 264.78 mL/g-VS and 24.62 mg INTF/(g-TS h), which was 1.33 and 1.83 times that of blank. Microbiological analysis demonstrated that the abundance of DIET-related microorganisms such as Syntrophomonas, Methanosarcina and Methanobacterium increased with the increasing dosage of S-mZVI.

Obtaining whispering gallery mode (WGM) lasing with prominent stability and high quality optical cavities is extremely desirable but still a great challenge. Despite the recent surge of reports on microspheres, nanowires and nanoplatelets metal halide crystals, there has few reports on the morphology of Hemispheres (HSs) in the form of uniform, component-tunable microcrystals. Here, CsPbX3 (X = Cl/Br) HSs with smooth surface and regular geometry structure were synthesized on silicon substrates by chemical vapor deposition (CVD) method, and the wavelength of laser can be continuously tuned from blue to green (450–540 nm) at room temperature by varying the halide composition. WGM laser with polarization ratio of 0.70 and cavity quality factor Q of 2485 were realized in the CsPbBr3 HS cavity. Besides, the crystal cavity suggested a high photonic and thermal stability for the superb capability of continuous stable lasing output under ambient conditions. All these results illustrate that the synthesis of cesium lead halide perovskite HSs may provide an alternative solution for fundamental researches and applications in optical devices.