Fabrication of an S-Scheme Heterojunction Photocatalyst MoS2/PANI with Greatly Enhanced Photocatalytic Performance.

As a promising catalyst, MoS2 has been widely studied owing to its high chemical reactivity, excellent electrical carrier mobility, good optical properties, and narrow band gap. However, the high recombination rate of photoinduced charge carriers limits its practical application in photocatalysis. In this study, MoS2 was coupled with PANI to fabricate an S-scheme heterojunction MoS2/PANI. The synthesized products were characterized systematically, and their photocatalytic properties were evaluated by photocatalytic degradation of norfloxacin (NOR) and rhodamine B (RhB). The obtained results indicated that the fabricated MoS2/PANI inorganic-organic heterojunction displayed tremendously enhanced photocatalytic activity. The degradation efficiencies for 60 mg L-1 of NOR and RhB are 86 and 100% under the simulated sunlight irradiation for 1 h with 10 mg of catalyst, which are 13 and 47 times higher than those of pure MoS2, respectively. Interestingly, it is superior to the previously reported related materials. The remarkably enhanced photocatalytic activity of MoS2 is assigned to the high charge conductivity feature of PANI and the formed S-scheme heterojunction that result in a steric separation of holes and electrons and conserve the initial powerful redox ability of the parent catalysts. This study provides a facile method to greatly improve the photocatalytic activity of MoS2 and facilitates its application for highly efficient removal of organic pollutants, such as antibiotic drugs and organic dyes, utilizing solar energy.

Uptake, accumulation and translocation of traditional and novel organophosphate esters by rice seedlings in the presence of micro(nano)-polystyrene plastics: Effects of concentration and size of particles.

Micro(nano)plastics (MNPs) and organophosphate esters (OPEs) are becoming ubiquitous as emerging pollutants. To data, the effects of MNPs on the uptake, accumulation and translocation of OPEs by rice plant are still unclear, especially for novel OPE species. In this study, the impacts of polystyrene MNPs of different sizes and concentrations on the uptake of eight OPEs (six traditional organophosphate triesters and two novel discovered aryl organophosphate triesters) by rice seedlings were investigated in hydroponic exposure experiments. The results showed that OPEs accumulated in a concentration-dependent manner in both the roots and shoots of rice seedlings. The impacts of MNPs on uptake by rice seedlings were concentration- and size-dependent by influencing the transpiration rate or activities of antioxidant enzymes. Especially, significant effects were usually found in exposure group of medium-size and high-concentration MNPs. MNPs had more obvious effects on OPE species with lower logKow in roots, whereas, more obvious effects on OPE species with higher logKow in shoots were observed. There was a significantly positive linear relationship between logTF and logKow (p < 0.001), and a significantly negative linear relationship between logRCF and logKow (p < 0.001), indicating that OPEs with higher hydrophobicity seemed to be more liable to be absorbed from solutions to roots, but difficult to further translocate to shoots. Without novel OPEs (bis-(2-ethylhexyl)-phenyl phosphate and tris(2,4-di-tert-butylphenyl)phosphate), better fits for a linear model for logKow and logRCF (or logTF) were exhibited, indicating differences between novel and traditional OPEs. This work highlights that the presence of MNPs could altered the characteristics of uptake, translocation and accumulation of OPEs in rice seedlings, and provides an important evidence for comprehensive control strategy of new pollutants.

Fabrication of a Heterojunction by Coupling a Metal-Organic Framework and N-Doped Carbon for the Photocatalytic Removal of Antibiotic Drugs with High Efficiency.

Norfloxacin (NOR) and tetracycline (TC), two widely used antibiotic drugs released to the aquatic environment, induce harm to ecosystems. In this study, an effective method was developed successfully to remove NOR and TC by photocatalysis with a novel heterojunction NC/NH2-MIL-53(Fe), which was fabricated by combining a metal-organic framework (MOF) material (NH2-MIL-53(Fe)) and N-doped carbon (NC) nanoparticles via a facile solvent thermal method. The prepared product exhibits outstanding photocatalytic efficiencies toward degradation of NOR and TC that are 15 and 6 times higher than those of pure NH2-MIL-53(Fe), respectively. Moreover, it is higher than those of the related materials reported previously. The greatly enhanced photocatalytic performance is assigned to the fabricated heterojunction with well-matched energy band gaps, where the NC acts as an efficient electron transfer/reservoir material to effectively promote the migration and transfer and restrain the recombination of charge carriers. In addition, the formed heterojunction increases specific surface area and light absorbance. The photocatalytic activity enhanced mechanism, degradation products, and pathway were investigated. The present study offers a novel strategy to significantly improve the photocatalytic performances of MOFs for highly efficient photocatalytic removal of antibiotic drugs in wastewater.

Fabrication of a Covalent Organic Framework-Based Heterojunction via Coupling with ZnAgInS Nanosphere with High Photocatalytic Activity.

Covalent organic frameworks (COFs) exhibit visible-light activity for the degradation of organic pollutants. However, the recombination rates of their photoinduced electron-hole pairs are relatively high, limiting their practical application. In this work, we fabricated a 1,3,5-triformylphloroglucinol (Tp) and p-phenylenediamine (Pa-1) (TpPa-1) COF-based heterojunction through coupling the TpPa-1 COF with a ZnAgInS nanosphere via a facile oil bath heating method. The results show that the prepared heterojunction exhibits outstanding catalytic activity for the degradation of high concentrations the antibiotic tetracycline (TC) and the dye rhodamine B (RhB), which is driven by simulated sunlight. Its degradation rates for RhB and TC were 30× and 18× higher than that of the pure TpPa-1 COF, respectively. The greatly enhanced photocatalytic performances can be ascribed to the formed heterojunction with good band-gap match, which promotes the migration and separation of light-induced electrons and holes and increases both light absorbance and the specific surface area. This study introduces an effective and feasible strategy for improving the photocatalytic performances of COFs via subtly integrating TpPa-1 COFs with a ZnAgInS nanosphere into an organic-inorganic hybrid. The results of the photocatalytic experiments indicate that the fabricated hybrid has a potential application in the highly efficient removal of organic pollutants.