Latest ArticlesIn the design of conjugated molecules, modular production enables materials to easily realize structure modification and precisely tune their photoelectrical property. Construction of a novel and universal building block is crucial to design and manufacture high performance and stable conjugated molecules for optoelectronic application. Herein, we originally demonstrated a universal 4-qualifiable fluorene-based building block, which is a fundamental molecular segment to functionalize and obtain novel conjugated materials. Compared to the traditional modification at 9-site, additional 4-position functionalization provided an exciting blueprint to not only tune electronic structure and excited state via p-n molecular design engineering and space charge-transfer strategy, but also allow for optimizing intermolecular arrangement and obtaining solution-processing ability. The introduction of the 4-site substituent in fluorene based semiconductors may endow materials with unique properties. Finally, we successfully prepared two stable deep-blue light-emitting conjugated polymer, PODOPF and PODOF, by utilizing the 4-substituent fluorene based building block. It is believable that the performance, stability and processibility of reported outstanding fluorene-based conjugated molecules can be further optimized based on this universal building block.
Advanced oxidation processes (AOPs) are promising technology to remove organic pollutant in water. However, the main problem in the AOPs is the low generation of hydroxyl radical (•OH) owing to the low decomposition efficiency of hydrogen peroxide (H2O2). Herein, the spinel type cobalt acid manganese (MnCo2O4) with flower morphology was fabricated through a co-precipitation method. In situ Fourier transform infrared spectroscopy confirms that the MnCo2O4 with the optimal molar ratio of Co and Mn precursors (CM3, Co: Mn = 3) has more Lewis acid sites compared with single metal oxide catalysts (Co3O4 and Mn2O3), leading to the excellent performances for H2O2 decomposition rate constant on CM3, which is about 15.03 and 4.21 times higher than those of Co3O4 and Mn2O3, respectively. As a result, the obtained CM3 shows a higher ciprofloxacin degradation ratio than that of Co3O4 and Mn2O3. Furthermore, CM3 shows an excellent stability during several cycles. This work proposes effective catalysts for ciprofloxacin decomposition and provides feasible route for treating practical environmental problems.
Metal-organic frameworks (MOFs) materials with highly ordered and porous crystalline structure, have excellent performance in advanced oxidation progresses (AOPs) for organic contaminants degradation in water treatment. This review intends to summarize the timely references and insights for the recent advances in MOFs that are used in AOPs. Starting with the preparation methodologies, including conventional hydrothermal method, electrochemical method, sol-gel method, and emerging microwave and ultrasound assisted synthesis methods. Application and mechanism for MOFs using in various AOPs of Fenton-like, photocatalysis, catalytic ozonation, persulfate catalysis and other emerging oxidation methods are emphatically discussed. We hope this review can comprehensively summarize the research and application progress of MOFs in AOPs, deepen the understanding of the catalytic mechanisms.
A novel Mo-doped CuO catalyst is developed and used for low-temperature NH3-SCR reaction. Compared with the undoped CuO sample, the Mo doped CuO catalyst shows an increased SCR performance with above 80% NOx conversion at 175 ℃. The XRD and Raman results have confirmed the incorporation of Mo metal ions into CuO lattice to form Mo-O-Cu species which may be related to the enhanced SCR activity. The XPS and UV–vis results reveal the creation of electron interaction between Cu and Mo in this Mo-O-Cu system which provides an increased amount of Lewis and Brønsted acid sites, thereby promoting the adsorption capacity of NH3 and NOx as verified by NH3-TPD and NOx-TPD characterization. Besides, it also promotes the formation of oxygen vacancies, leading to the increasing of chemisorbed oxygen species, which improves the NO oxidation to NO2 activity. Furthermore, in situ DRIFTS technology was also used to study the reaction mechanism of this Mo doped CuO catalyst. The formed NO2 could react with NHx (x = 3, 2) species to enhance the low-temperature NH3-SCR activity via the "fast-SCR" reaction pathway. The nitrate and nitrite ad-species may react with NH3 and NH4+ ad-species through the L-H pathway.
The increasing occurrence of pesticide micropollutants highlights the need for innovative water treatment technologies, particularly for small-community and household applications. Electro-oxidation is being widely studied in this area, unfortunately, safe, stable and efficient electrocatalytic anodes without released heavy metal ions are still highly required. In this study, we fabricated a Pt/Ti anode by high energy pulse magnetron sputtering (HiPIMS-PtTi) which was used to decompose dichlorvos (DDVP) and azoxystrobin (AZX) in water. The results show that the reaction rate constant (kENR) on HIPIMS was 35.7 min–1 (DDVP) and 41.3 min–1 (AZX), respectively, superior to electroplating Pt/Ti anode (EP-PtTi). The identification of radicals (•OH, 1O2, •O2−) and micro-area analyses evidenced that Pt atoms were embedded into the TiO2 lattice on the surface of Ti plate by high-energy ions, which resulted in more adsorbed hydroxyls, and higher production of •OH under polarization conditions. Besides, the electro-oxidation intermediates of DDVP and AZX were identified and the degradation pathways were speculated: (1) indirect oxidation dominated by •OH attack, and (2) direct electron transfer reaction of pesticides on the anode surface. The cooperated reactions achieve the complete degradation and highly efficient mineralization of DDVP and AZX.
Exposure to environmental cadmium increases the health risk of residents. Early urine metabolic detection using high-resolution mass spectrometry and machine learning algorithms would be advantageous to predict the adverse health effects. Here, we conducted machine learning approaches to screen potential biomarkers under cadmium exposure in 403 urine samples. In positive and negative ionization mode, 4207 and 3558 features were extracted, respectively. We compared seven machine learning algorithms and found that the extreme gradient boosting (XGBoost) and random forest (RF) classifiers showed better accuracy and predictive performance than others. Following 5-fold cross-validation, the value of area under curve (AUC) was both 0.93 for positive and negative ionization modes in XGBoost classifier. In the RF classifier, AUC were 0.80 and 0.84 for positive and negative ionization modes, respectively. We then identified a biomarker panel based on XGBoost and RF classifiers. The incorporation of machine learning models into urine analysis using high-resolution mass spectrometry could allow a convenient assessment of cadmium exposure.
Carbonized polymer dots (CPDs) modified layer-structured CdBiO2Br (CPDs/CdBiO2Br) Z-scheme heterojunction hybrid material has been synthesized via simple solvothermal method. The hybrid material with Z-scheme heterojunction can effectively maintain the original highly oxidizing holes of CdBiO2Br and the highly reducing electrons of CPDs. In addition, the construction of heterostructure is beneficial to the migration and separation of photogenerated carriers. Under visible light irradiation, 6 wt% CPDs/CdBiO2Br showed the best catalytic activity for degradation of organic pollutants. Free radical capture experiments and ESR analysis confirmed that the main active species are •O2− and h+. The decomposition process of organic pollutants was analyzed by LC-MS. Finally, the probable visible light mechanism performance of CPDs/CdBiO2Br as direct Z-scheme heterojunction photocatalytic materials was proposed.
Challenges of achieving efficient photodimerization of azaanthracene derivatives remain due to the low selectivity and slow reaction rate. In this paper, cucurbit[10]uril (CB[10]), with the largest rigid and hydrophobic cavity among CB[n]s, was used to affect the photodimerization reaction of four water-soluble 1-(2-)substituted azaanthracene derivatives (1-4). It revealed that 1-4 could form 1:2 host-guest complexes with CB[10] in aqueous solution. Irradiation of 1 in the presence of 0.5 equiv. of CB[10] selectively produced a head-to-tail (anti-HT) photodimer product. As for 2-4, CB[10] acted as a nanoreactor accelerating their photodimerization reaction in water. Our results suggest that photodimerization of azaanthracene derivatives could be promoted by the CB[10]-based host-guest strategy with high efficiency and selectivity.
The matched energy band structure and efficient carrier separation efficiency are the keys to heterogeneous photocatalytic reactions. A novel organic/inorganic step scheme (S-scheme) heterojunction PDI-Urea/BiOBr composite photocatalyst was constructed by simple solvothermal reaction combined with in-situ growth strategy. The composite photocatalyst not only has high chemical stability, but also can generate and accumulate a large number of active species (h+, •O2−, •OH, H2O2). PDI-Urea/BiOBr showed higher photocatalytic activity for the degradation of antibiotic such as ofloxacin (OFLO), tetracycline (TC) and the production of H2O2 in the spectral range of 400–800 nm. The apparent rate constant of 15% PDI-Urea/BiOBr for photocatalytic degradation of TC (or OFLO) was 2.7 (or 2.5) times that of pure BiOBr and 1.7 (or 1.8) times that of pure PDI-Urea. The H2O2 evolution rate of 15% PDI-Urea/BiOBr was 2.5 times that of PDI-Urea and 1.5 times that of BiOBr, respectively. This work has formed a mature S-scheme heterojunction design thought and method, which offers new visions for the development of heterogeneous photocatalysts.
Ammonia is one of the most essential chemicals in the modern society but its production still heavily relies on energy-consuming Haber-Bosch processes. The photocatalytic reduction of nitrogen with water for ammonia production has attracted much attention recently due to its synthesis under mild conditions at room temperature and atmospheric pressure using sunlight. Herein, we report a high-performance Au/MIL-100(Cr) photocatalyst, comprising MIL-100(Cr) and Au nanoparticles in photocatalytic nitrogen reduction to ammonia at ambient conditions under visible light irradiation. The optimized photocatalyst (i.e., 0.10Au/MIL-100(Cr)) achieved the excellent ammonia production rate with 39.9 µg gcat−1 h−1 compared with pure MIL-100(Cr) (2.73 µg gcat−1 h−1), which was nearly 15 times that on pure MIL-100(Cr). The remarkable activity could be attributed to the adsorption-plasmonic synergistic effects in which the MIL-100(Cr) and Au are responsible to the strong trapping and adsorption of N2 molecules and photo-induced plasmonic hot electrons activating and decomposing the N2 molecules, respectively. This study might provide a new strategy for designing an efficient plasmonic photocatalyst to improve the photocatalytic performance of N2 fixation under visible light irradiation.
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