Latest ArticlesThe extraction of uranium from seawater is essential for the sustainable development of the nuclear industry. Covalent organic frameworks (COFs) exhibit significant potential in uranium extraction from seawater due to their high stability, designability, and large specific surface area. Herein, a vinyl-decorated covalent organic framework, designated as COF-IHEP5, was synthesized through acid-catalyzed solvothermal method. COF-IHEP5-COOH was constructed by post-modification strategy through the "thiol-ene" click reaction, where COF-IHEP5-COOH contains hydrazone-carbonyl and flexible carboxylic acid chelating sites on pore wall. This modification facilitates synergistic adsorption of uranium by utilizing a "nano trap" that is embedded within the COF framework. The maximum adsorption capacity of the post-modified COF-IHEP5-COOH for UO22+ has reached 543.8 mg/g, representing a 1.5-fold increase compared to the unmodified COF-IHEP5. Additionally, COF-IHEP5-COOH demonstrates an extraction efficiency of approximately 80% for uranium from spiked natural seawater, featuring 4.5 times higher selectivity than vanadium. The DFT calculation results show that the adsorption of uranium orginated from the synergistic coordination of the skeleton in COF-IHEP5-COOH and carboxyl group on the side arm. This research highlights the remarkable potential of pore surface engineering in customizing active adsorption sites and offers new insights for the design of functionalized uranium adsorbents with superior binding affinity and adsorption capacities.
In this study, we successfully construct a non-noble metal-based Schottky photocatalyst MX@MIL-125 (MX is shorted for Ti3C2 MXene) by combining the Ti-based metal-organic framework MIL-125(Ti) with Ti3C2 MXene. Leveraging the unique surface properties of MXene, a close and uniform distribution of nano-cake-like MIL-125(Ti) was achieved on the two-dimensional Ti3C2 MXene layers. The introduction of Ti3C2 MXene not only broadens the light absorption range but also adjusts the local coordination structure between the interfaces. This heterojunction significantly promotes the separation and transfer of photogenerated carriers. The photocatalytic N2 reduction efficiency of MX@MIL-125-20 is 11-fold higher than that of pristine MIL-125(Ti) (48.8 vs. 4.6 µmol gcat−1 h−1), and the photodegradation efficiency of tetracycline hydrochloride (TCH) is increased by about 18% (92.95% vs. 74.67%). This work may provide new insights for the design of innovative photocatalysts for various chemical redox reactions.
While TiO2 is a promising catalyst for electrocatalytic nitrate (NO3--N) reduction to NH3 (ENRR), how the crystalline phase (anatase (A) or rutile (R)) and surface oxygen vacancy (Ov) synergize in ENRR remains ambiguous. Herein a series of nitrogen-doped TiO2 catalysts with controlled phase composition and Ov number are prepared by calcinating titanium nitride powders in an air atmosphere at specific temperatures (N-TiO2-x, x = 450–750 ℃). Generally, higher temperatures lead to increased R-TiO2 content but decreased Ov number. The ENRR performances of these N-TiO2 are higher than that of pure A- and R-TiO2, and vary in volcano-like trends against both the R-TiO2 content and Ov number. Combined control experiments and theoretical simulation demonstrate that Ovs are the active sites for ENRR, but their functions differ between A-TiO2 and R-TiO2. Specifically, the Ovs on R-TiO2 are more active in NO3- conversion and renew more easily during reaction, while those on A-TiO2 perform better in proton adsorption. The synergy between Ovs on R-TiO2 and A-TiO2 promotes the ENRR on the phase-mixed N-TiO2. Furthermore, as the catalyst varies from N-TiO2–450 to -750, the overall efficacy of Ovs in proton transfer decreases due to the decreased number of Ovs on A-TiO2, while the mean activity and renewability of them improve as a higher proportion of Ovs are distributed on R-TiO2. The tug-of-war between the two opposing trends results in a peak ENRR performance on N-TiO2–650 (mass activity: 22.2 mgN h-1 gcat.-1; NH3-N selectivity: 98.8%; Faradaic efficiency: 79.4%). These findings offer a deeper understanding of ENRR on TiO2, and provide new insights for the design of efficient catalysts.
Photocatalysis shows promising application in efficient reduction of nitrogen oxides (NOx). However, the sluggish selectivity in nitric oxide removal with reductants, resulting in the formation of undesired N2O byproducts, presents a great challenge. In this work, complete prohibition of nitric oxide generation in photo-removal of NO with carbon particulate is successfully achieved through the rational regulation of electron-trapping centers on TiO2 nanosheets (TNS) surface achieved by the surface reduction treatment with NaBH4. The efficient suppression (100%) of N2O generation is ascribed to the more stable N2O adsorption on the active (001) crystalline plane of TNS and the electron-capturing ability around oxygen vacancies based on the density functional theory (DFT) and experimental investigations. The existence of O2 and H2O effectively promote the photocatalytic activity of NO reduction but demonstrate no adverse effect on N2O suppression. The optimal photocatalytic NO reduction activity with the highest CO2 formation rate of 5.54 mg g−1 h−1 without N2O formation is achieved over the optimized 0.135-TNS. These investigations guide the development of feasible photocatalytic treatment of air pollutants, emphasizing the significance of managing electron capture and gas adsorption for efficient byproduct control in pollutants removal.
In situ therapeutic agent production strategy is promising to overcome the drawbacks of direct drug delivery. Hypoxia provides a great target for precise treatment of tumor. Here we report a copper ion competition-based nanoparticle (NP) for hypoxia-activated formation of diethyldithiocarbamate (DTC)-copper complex, an immunogenic cell death (ICD) inducer. The NP is composed of an amphiphilic hypoxia-responsive DTC precursor and a fluorescence quenched copper ion-chelated squaric acid. In hypoxic tumor cells, the azobenzene linker in DTC precursor can be cleaved through bioreduction, leading to DTC release and subsequent copper ion exchange between DTC and squaric acid. Simultaneous formation of toxic DTC-copper complexes and fluorescence recovery will allow for visualization of in situ therapeutic agents production. Furthermore, the DTC-copper complexes can induce ICD and promote cytotoxic T lymphocyte infiltration for cancer immunotherapy. This study not only provides a promising hypoxia-activated nanomedicine for precision cancer therapy, but also a visualization strategy for evaluating the treatment process.
Mechanosensitive channel proteins serve important physiological functions in biological systems. Building artificial transmembrane channels to mimic the function of natural channels would provide a new strategy for treating channel-related diseases. In this paper, we describe the design and construction of artificial channels derived from pillar[5]arene backbones with different flexibilities, which are determined by the alkyl chain length. Importantly, the ion transport activities of the channels can be activated by increasing the membrane curvature and tension, which endows the channel with mechano-gating behavior.
The development of advanced anti-counterfeiting technology using photochromic inorganic materials with dynamic optical signals has garnered significant interest, but the limited color response and un-controlled photochromic kinetics largely restrict their practical application. In this work, we report the design of photochromic supramolecular assembly based on host-guest chemistry, enabling kinetics-tunable time-encoded anti-counterfeiting. By co-assembling of photochromic tungsten oxide quantum dots (WO3 QDs) with cucurbit[7]uril (CB[7]), we developed a kinetics-tunable photochromic supramolecular assembly (WO3CB[7]). The WO3CB[7] assembly exhibits distinct photochromic kinetics compared to free WO3 QDs due to efficient suppression of photogenerated decomposition of water adsorbed on WO3 QDs, as verified by spectral and photophysical analysis. The photochromic kinetics can be readily modulated by adjusting the WO3 QDs to CB[7] ratio. The kinetics-tunable photochromic WO3CB[7] assembly has been successfully applied as innovative anti-counterfeiting materials for fabricating time-encoded anti-counterfeiting arrays and information encryption system. The irradiation time serves as a key parameter for decrypting the final information, thereby enhancing the complexity of replication and counterfeiting. This approach offers a simple, scalable and generalizable strategy for designing advanced optical anti-counterfeiting materials by integrating inorganic photochromic materials with the supramolecular strategy.
Sewage sludge (SS) is a by-product of wastewater treatment. Recovering resources from SS, particularly nitrogen (N) and phosphorus (P), is emerging as a crucial approach to promoting carbon neutrality within the treatment sector. This need necessitates developing methods that not only recover these vital nutrients but also mitigate the release of nitrogenous pollutants. Our review addresses the recovery of N and P from SS, aiming to reduce the dissemination of harmful nitrogen compounds into the environment. We provide a comprehensive analysis of techniques ranging from ultrasonic treatment and aerobic/anaerobic digestion to thermochemical conversion methods such as incineration, pyrolysis, and gasification. We also evaluate strategies like bio-enhanced phosphorus recovery and electrochemical methods, with the dual goal of diminishing nitrogen emissions and reclaiming phosphorus from SS. The review synthesizes advanced techniques and strategies to support emission control and resource recovery, offering a comprehensive guide for advancing SS treatment technologies.
The electrostatic repulsion between the anode and ammonia (NH4+) can cause chlorine radicals (Cl•) at the interface to self-compounding into low oxidating species, weakening the treatment performance of ammonia-nitrogen (NH4+-N) wastewater. This study introduces electron-rich elements into the tetrahedral sites (ATd2+) of spinel cobalt oxide (Co3O4) for efficient and selective NH4+-N mineralization induced by interfacial Cl•. Batch experiments, in-situ characterizations, and theoretical calculations confirm that CuTd2+ have moderate energy level matching and strong binding energy with NH4+ compared to NiTd2+ and ZnTd2+. NH4+ can effectively overcome electrostatic repulsion and enrich on CuxCo3-xO4 anode. More importantly, the interaction of CuTd2+-O-CoOh3+ weakens the binding of Cl• at CoOh3+ sites, promoting the desorption of Cl• from the anodic interface. As a result, NH4+-N is mineralized by Cl• into N2 with a rate of 4.4 × 10–2 min-1, superior to Co3O4 and commercial dimensionally stable anodes. Finally, the scale-up experiment using a continuous flow reactor realizes long-term stability for NH4+-N wastewater treatment, in which 100% of NH4+-N and 88.3% of total nitrogen can be continuously eliminated in 96 h. This study offers an in-depth understanding of interfacial reactions in the EC system and guides the design and synthesis of superior anodes for environmental remediation.
It is still challenging to develop nanomedicines with full-active and simple components to tackle osteoarthritis (OA) through restoration of inflammation and cartilage homeostasis. Here, we report the synthesis of a bioactive asymmetric phosphorus dendrimer bearing an azabisphosphonate (ABP) group, termed as G0.PD-ABP, by a divergent method for intracellular bromelain (Bro) delivery. The formed G0.PD-ABP/Bro nanocomplexes (NCs) exhibit a uniformly dispersed spherical shape with a mean size of 148.4 nm and can achieve more significant intracellular Bro delivery than symmetric phosphorus dendrimer (G0.PD) without ABP via the clathrin-mediated endocytosis pathway. Importantly, the NCs efficiently block the activation of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and nuclear factor kappa-B (NF-κB) by amplifying the anti-inflammatory function of Bro and synergizing with the immunomodulatory activity of dendrimers, thereby facilitating the polarization of macrophages towards M2 phenotype and down-regulating inflammatory cytokine secretion to lead to suppressed chondrocyte apoptosis. Compared with G0.PD/Bro NCs, an OA mouse model treated with G0.PD-ABP/Bro NCs demonstrates more remarkable alleviation of pathological features such as cartilage degradation, bone erosion, and synovial inflammation. This study emphasizes the positive contribution of structural asymmetry of phosphorus dendrimers in protein delivery and provides a viable strategy for the treatment of OA or other inflammatory diseases through enhanced immune modulation of macrophages.
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