Latest ArticlesPhotocatalytic CO2 reduction reaction (CO2RR) is one of the promising strategies for sustainably producing solar fuels. The precise identification of catalytic sites and the enhancement of photocatalytic CO2 conversion is imperative yet quite challenging. This critical review summarizes recent advances in porous photo-responsive polymers, including covalent organic frameworks (COFs), covalent triazine frameworks (CTFs), and conjugated microporous polymers (CMPs), those can be rationally designed from the molecular level for visible-light-driven photocatalytic CO2 reduction. Additionally, special emphasis is placed on how the well-defined active sites on these polymers can influence their properties and photocatalytic performance. The precise regulation and control of microenvironments and electronic properties of metal active centers are crucial for boosting catalytic efficiency and selectivity, as well as for the design of better photocatalysts for CO2 reduction.
Photocatalysis is widely regarded as a highly promising sustainable technique for addressing the challenges posed by environmental pollution and energy provision. In recent years, metal-loaded MOFs has become a rising star within the domain of photocatalysis due to its high specific surface area and porosity, adjustable structure, diverse and abundant catalytic components, which has exhibited excellent photocatalytic activity and exhibit great potential in a range of disciplines. In this paper, the principles for evaluating the photocatalytic performance of MOFs-based materials were firstly introduced, and some typical examples were also listed accordingly. Along with this, particular emphasis is paid to the main factors affecting the photocatalytic performance of metal-loaded MOFs. Then the synthesis and design strategies of MOFs loaded metal entities of varying sizes (single atoms, nanoclusters, and nanoparticles), and their applications in photocatalytic CO2 reduction, hydrogen production, photooxidation and photocatalytic hydrogenation were summarized and discussed. Finally, the opportunities and challenges faced in this kind of MOFs-based composites were analyzed from different perspectives. This report is expected to help researchers design and develop high-performance MOFs-based photocatalytic materials.
Organic pollutants are harmful and toxic chemical substances that adversely threaten human health and the living environment all over the world. More and more studies have been investigating the relationship between low level of human exposure of organic compounds and various internal diseases. For the sake of assessing disease risk due to organic compounds contact in a particular location, it is imperative for relevant government departments to make a human health risk assessment in view of the organic pollutants’ bioavailability and their dosage-response correlations. It is inevitable to make use of an efficient method to detect organic pollutants, which is significant for public health and safety. Fluorescent assays based on carbon dots thus would provide a very plausible candidate method. After consulting a large number of literatures, we offer a comprehensive review of the sensing applications of carbon dots for organic pollutants.
Inactivation of carbon-based transition metal catalysts, which was caused by electron loss, limited their application in advanced oxidation processes. Therefore, Co and TiO2 double-loaded carbon nanofiber material (Co@CNFs-TiO2) was synthesized in this study. Photocatalytic and chemical catalytic systems were synergized efficiently. Tetracycline was eliminated within 15 min. The degradation rate remained above 90% after five cycles, and the 50% promotion proved the high stability of Co@CNFs-TiO2. The main reactive oxygen species in this system were sulfate radicals, whereas Co and TiO2 represented the active sites of the catalytic reaction. Electrons generated from TiO2 during the photocatalytic process were transferred to Co, which promoted the Co(Ⅲ)/Co(Ⅱ) cycle and maintained Co in a low-valence state, thereby stimulating the generation of sulfate radicals. In this study, the effective regulation of reactive oxygen species in the reaction system was realized. The results provided a guidance for in situ electron replenishment and regeneration of carbon-based transition metal catalysts, which will expand the practical application of advanced oxidation processes.
Membrane distillation (MD) has gained extensive attention for treating highly saline wastewater. However, membrane scaling during the MD process has hindered the rapid development of this technology. Current approaches to mitigate scaling in membrane distillation focus primarily on achieving enhanced hydrophobicity and even superhydrophobicity via utilizing fluorinated fibrous membrane or introducing perfluorosilane modification. Considering the environmental hazards posed by fluorinated compounds, it is highly desirable to develop non-fluorinated membranes with enhanced anti-scaling properties for effective membrane distillation. In this study, we present a non-fluorinated liquid-like MD membrane with exceptional anti-scaling performance. This membrane was facilely fabricated by grafting linear polydimethylsiloxane (LPDMS) onto a hydrophilic polyether sulfone (PES) membrane pre-coated with the intermediate layers of polydopamine and silica (denoted as LPDMS-PES). Remarkably, LPDMS-PES manifested a drastically improved scaling resistance in continuous MD tests than its perfluorinated counterpart, i.e., 1H,1H,2H,2H-perfluorooctyltrichlorosilane-modified PES membrane (PFOS-PES), in both heterogeneous nucleation-dominated and crystal deposition-dominated scaling processes, despite the latter having a smaller surface energy. LPDMS-PES demonstrated a reduction of crystal accumulation of approximately 85% for NaCl and 73% for CaSO4 in the heterogeneous nucleation-dominated scaling process compared to PFOS-PES. Additionally, in the crystal deposition-dominated scaling process LPDMS-PES exhibited a reduction of about 70% in scale accumulation. These results explicitly evidenced the great potential of the liquid-like membrane to minimize scaling in membrane distillation by inhibiting both scale nucleation and adhesion onto the membrane. We believe the findings of this study have important implications for the design of high-performance MD membranes, particularly in the quest for environmentally sustainable alternatives to perfluorinated materials.
Zirconium-based metal-organic cages (Zr-MOCs) typically exhibit high stability, but their structural and application reports are scarce due to stringent crystallization conditions. We have successfully fluorinated the classical Zr-MOCs (ZrT-3) for the first time, obtaining the fluorinated MOCs (ZrT-3-F). Notably, ZrT-3-F not only inherits the high stability of its parent structure, but also acts as a catalyst for the effective oxidation of benzyl thioether for the first time. The reaction can reach a conversion rate of 99% in 6 h, and the selectivity reaches 95%, which far exceeds the non-fluorinated ZrT-3. This work proves that the specific functionalization of the classical Zr-MOCs can further expand their application potential, such as catalysis.
Deep learning neural network incorporating surface enhancement Raman scattering technique (SERS) is becoming as a powerful tool for the precise classifications and diagnosis of bacterial infections. However, the large amount of sample requirement and time-consuming sample collection severely hinder its applications. We herein propose a spectral concatenation strategy for residual neural network using non-specific and specific SERS spectra for the training data augmentation, which is accessible to acquiring larger training dataset with same number of SERS spectra or same size of training dataset with fewer SERS spectra, compared with pure non-specific SERS spectra. With this strategy, the training loss exhibit rapid convergence, and an average accuracy up to 100% in bacteria classifications was achieved with 50 SERS spectra for each kind of bacterium; even reduced to 20 SERS spectra per kind of bacterium, classification accuracy is still > 95%, demonstrating marked advantage over the results without spectra concatenation. This method can markedly improve the classification accuracy under fewer samples and reduce the data collection workload, and can evidently enhance the performance when used in different machine learning models with high generalization ability. Therefore, this strategy is beneficial for rapid and accurate bacteria classifications with residual neural network.
Photocatalytic technology harnesses solar energy to facilitate chemical transformations, presenting significant potential in energy generation and environmental remediation. However, the conventional O2 evolution process is hindered by high reaction barriers and inefficiencies, which limit its widespread application. Therefore, exploring novel photocatalytic coupling strategies to replace water oxidation has become a key route to enhance the efficiency of H2 production. In this review, organic pollutants removal and the valorization of organics as substitutes for water oxidation coupling strategies for photocatalytic H2 production are comprehensively summarized. These strategies not only circumvent the high reaction barriers associated with O2 evolution to enhance the H2 production but also aid in the removing of organic pollutants or synthesis of value-added chemicals. We also present future research directions and underscore the significance of advanced catalyst design, in-depth analysis of reaction mechanisms, and systematic optimization strategies in realizing an efficient and sustainable photocatalytic process. This guidance is anticipated to provide theoretical and practical new insights for the future development of photocatalytic coupling reactions, fostering further explorations in the realm of renewable energy and environmental governance.
Flexible energy storage devices have been paid much attention and adapts to apply in various fields. Benefiting from the active sites of boron (B) and phosphorus (P) doping materials, co-doped carbon materials are widely used in energy storage devices for the enhanced electrochemical performance. Herein, B and P co-doped flexible carbon nanofibers with nitrogen-rich (B-P/NC) are investigated with electrospinning for sodium-ion battery. The flexible of binderless B-P/NC with annealing of 600 ℃ (B-P/NC-600) exhibits the remarkable performance for the robust capacity of 200 mAh/g at 0.1 A/g after 500 cycles and a durable reversible capacity of 160 mAh/g even at 1 A/g after 12, 000 cycles, exhibiting the equally commendable stability of flexible B-P/NC-600. In addition, B-P/NC-600 delivers the reversible capacity of 265 mAh/g with the test temperature of 60 ℃. More importantly, the flexible B-P/NC-600 is fabricated as anode for the whole battery, delivering the capacity of 90 mAh/g at 1 A/g after 200 cycles. Meanwhile, theoretical calculation further verified that boron and phosphorus co-doping can improve the adsorption capacity of nitrogen carbon materials. The favorable performance of flexible B-P/NC-600 can be ascribed to the nitrogen-rich carbon nanofibers with three-dimensional network matrix for the more active site of boron and phosphorus co-doping. Our work paves the way for the improvement of flexible anodes and wide-operating temperature of sodium-ion batteries by doping approach of much heteroatom.
In-situ enhanced bioreduction by functional materials is a cost-effective technology to remove chlorinated hydrocarbons in groundwater. Herein, a novel polydopamine (PDA)-modified biochar (BC)-based composite containing nanoscale zero-valent iron (nZVI) and poly-l-lactic acid (PLLA) (PB-PDA-Fe) was synthesized to enhance the removal of 1,1,1-trichloroethane (1,1,1-TCA) in simulated groundwater with actual site sediments. Its impact on functional microbial community structure in system was also investigated. The typical characterizations revealed uniform dispersion of PLA and nZVI particles on the BC surface, being smoother after PDA coating. The composite exhibited a significantly higher performance on 1,1,1-TCA removal (82.38%, initial concentration 100 mg/L) than Fe-PDA and PB-PDA treatments. The diversity and richness of the microbial community in the composite treatment consistently decreased during incubation due to a synergistic effect between PLLA-BC and nZVI. Desulfitobaterium, Pedobacter, Sphaerochaeta, Shewanella, and Clostridium were identified as enriched genera by the composite through DNA-stable isotope probing (DNA-SIP), playing a crucial role in the bioreductive dechlorination process. All the above results demonstrate that this novel composite selectively enhances the activity of microorganisms with extracellular respiration functions to efficiently dechlorinate 1,1,1-TCA. These findings could contribute to understanding the responsive microbial community by carbon-iron composites and expedite the application of in-situ enhanced bioreduction for effective remediation of chlorinated hydrocarbon-contaminated groundwater.
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