Latest ArticlesDefects can strongly affect the lattice, strain, and electronic structures of nanomaterials photocatalysts, like a double-edged sword of both positive significance and negative influence on photocatalytic performances. To date, most studies into defects only partially elucidated their beneficial or detrimental roles in photocatalysis. However, a quantitative understanding of the photocatalytic performances modulated by defect concentration still needs to be discovered. Here, a series of TiO2−X mesoporous spheres (MS) with different oxygen vacancy concentrations for photocatalytic applications were prepared by high-temperature chemical reduction. The link between oxygen vacancy concentration and photocatalytic performance was successfully established. The localization of carriers dominated by the Stark effect is first enhanced and then weakened with increasing oxygen vacancy concentration, which is a crucial factor in explaining the double-edged sword role of defect concentration in photocatalysis. As the reduction temperature rises to 300 ℃, carrier localization dominated by the quantum-confined Stark effect maximizes the separation ability of photo generated electron hole pairs, thus exhibiting the best catalytic performance for photocatalytic hydrogen production and the degradation of organic pollutants, as demonstrated by a hydrogen evolution rate of 523.7 µmol g-1 h-1 and a ninefold higher RhB photodegradation rate compared to TiO2 MS. The work offers excellent flexibility for precisely constructing high-performance photocatalysts by understanding vacancy engineering.
Microbial fabrication of metal nanoparticles (MNPs) has received significant attention due to the advantages of low toxicity, energy efficiency and ecological safety. Diverse groups of MNPs can be synthesized intracellularly or extracellularly by various wild-type microorganisms, including bacteria, fungi, algae and viruses. Synthetic biology approaches, represented by genetic engineering, have been applied to overcome the shortcomings in productivity, stability, and controllability of biosynthetic MNPs. Scanning electron microscope (SEM), transmission electron microscope (TEM) and other characterization techniques assist in deciphering their unique properties. In addition, biosynthetic MNPs have been widely explored for the utilization in environmental remediation and contaminant detection. And machine learning contains a great potential for designing targeted MNPs and predicting their toxicity. This review provides a comprehensive overview of the research progress in the microbial synthesis of MNPs. An outlook on the current challenges and future prospects in the biologically controllable synthesis and engineering environmental applications of MNPs is also provided in this review.
A facile visible-light-induced 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) catalyzed four-component reaction of alkenes, quinoxalin-2(1H)-ones, P4S10 and alcohols has been developed at room temperature. This tandem reaction provides an efficient strategy for the construction of various phosphorodithioate-containing quinoxalin-2(1H)-ones with moderate to good yields by using air (dioxygen) as the green oxidant. Experimental studies revealed a radical process was involved in this photochemical reaction.
Stimulus-responsive room-temperature phosphorescence (RTP) materials have gained significant attention for their important optoelectronic application prospects. However, the fabrication strategy and underlying mechanism of stimulus-responsive RTP materials remain less explored. Herein, we present a reliable strategy for achieving pH-responsive RTP materials by integrating poly(vinyl alcohol) (PVA) with carboxylic acid or amino group functionalized terpyridine (Tpy) derivatives. The resulting Tpy derivatives-based RTP materials displayed reversible changes in emission color, intensity, and lifetime of both prompt and delayed emission. Notably, the RTP emission undergoes a significant diminish upon exposure to acid due to the protonation of Tpy units. Taking advantage of the decent RTP emission and pH-responsiveness of these RTP films, a spatial-time-resolved anti-counterfeiting application is demonstrated as a proof-of-concept for largely enhancing the security level. This study not only provides new prospects for developing smart RTP materials but also promotes the advancement of optical anti-counterfeiting applications.
Four novel compounds based on hexanuclear thorium cluster were synthesized and characterized. Compound 1 [Th6(HPyC)8(HCOO)4] is formed by replacing formate ligands of preassembled thorium cluster [Th6O4(OH)4(H2O)6(HCOO)12] with eight H2PyC (4-pyrazolecarboxylic acid) under solvothermal conditions. Each of the HPyC− ligands is coordinated with one Cu2+ to form the (4,8)-connected -net structure of compound 2 [(CuCl2)2Th6(HPyC)8(HCOO)4]. In compound 3 [(CuCl2)2Th6(HPyC)10(HCOO)4], ten of the formate ligands of preassembled Th6 cluster are replaced by HPyC− ligands. Compared with compound 2, the two extra HPyC− ligands in the equatorial plane of the Th6 cluster in compound 3 are not further connected to copper ions. Therefore, the topology structure of compound 3 is same with that of compound 2. Compound 4 [(Cu3Cl2)(CuCl2)Th6(PyC)3(HPyC)4(HCOO)5] contains three kinds of metal nodes, Th6 cluster, Cu3 cluster and mononuclear Cu2+, and exhibits a novel (5,7)-connected net structure, which was first discovered in actinide MOFs. Furthermore, considering the satisfactory stability of compound 4 and its unsaturated metal nodes and Lewis acid sites, the catalysis of cycloaddition of CO2 was further studied. We found that this thorium-copper heterometallic cluster organic framework can be used as a potential actinide functional material for catalyzing the efficient CO2 conversion to value-added products.
As a key biomarker for noninvasive diagnosis of diabetes, the selective detection of trace acetone in exhaled gas using a portable and low-cost device remains a great challenge. Semiconductor metal oxide (SMO) based gas sensors have drawn signification attention due to their potential in miniaturization, user-friendliness, high cost-effectiveness and selective real-time detection for noninvasive clinical diagnosis. Herein, we propose a one-pot solvent evaporation induced tricomponent co-assembly strategy to design a novel ordered mesoporous SMO of silica-implanted WO3 (SiO2/WO3) as sensing materials for trace acetone detection. The controlled co-assembly of silicon and tungsten precursors and amphiphilic diblock copolymer poly(ethylene oxide)-block-polystyrene (PEO-b-PS), and the subsequent thermal treatment enable the local lattice disorder of WO3 induced by the amorphous silica and the formation of ordered mesoporous SiO2/WO3 hybrid walls with a unique metastable ε-phase WO3 framework. The obtained mesoporous SiO2/WO3 composites possess highly crystalline framework with large uniform pore size (12.0–13.3 nm), high surface area (99–113 m2/g) and pore volume (0.17–0.23 cm3/g). Typically, the as-fabricated gas sensor based on mesoporous 2.5%SiO2/WO3 exhibits rapid response/recovery rate (5/17 s), superior sensitivity (Rair/Rgas = 105 for 50 ppm acetone), as well as high selectivity towards acetone. The limit of detection is as low as 0.25 ppm, which is considerably lower than the thresh value of acetone concentration (>1.1 ppm) in the exhaled breath of diabetic patients, demonstrating its great prospect in real-time monitoring in diabetes diagnosis. Moreover, the mesoporous 2.5%SiO2/WO3 sensor is integrated into a wireless sensing module connected to a smart phone, providing a convenient real-time detection of acetone.
A novel amine-modified pillar[5]arene bonded porous silica adsorbent (DETA-P5S) was designed to be applied to dynamic CO2 adsorption and selective separation of CO2 over N2 and CH4 gases mixture. The results demonstrated that reasonable introduction of DETA into the BE-P5 bonded silica support has significantly increased the adsorption capacity of CO2. The DETA-P5S has the optimal adsorption capacity of 9.1 mmol/g with 5 vol% CO2 at 40 ℃. The main reason of this increased capacity could be attributed to the enhanced CO2 diffusion into porous adsorbent for its better dispersion in the pores of amine-pillar[5]arene cavity and active site of DETA. Furthermore, the dynamic saturation adsorption capacities of DETA-P5S were 7.11 (0.37) and 6.18 (0.44) mmol/g for CO2/N2 and CO2/CH4, respectively, both the gas mixtures showed high separation selectivity. Simultaneously, the DETA-P5S can maintain outstanding CO2 adsorption capacity after fifteen regeneration cycles. Consequently, the designed DETA-P5S could serve as a promising adsorbent for CO2 capture and storage.
Parkinson’s disease (PD) is an aging-associated neurodegenerative movement disorder with increasing morbidity and mortality rates. The current gold standard for diagnosing PD is clinical evaluation, which is often challenging and inaccurate. Metabolomics and lipidomics approaches have been extensively applied because of their potential in discovering valuable biomarkers for medical diagnostics. Here, we used comprehensive untargeted metabolomics and lipidomics methodologies based on liquid chromatography-mass spectrometry to evaluate metabolic abnormalities linked with PD. Two well-characterized cohorts of 288 plasma samples (143 PD patients and 145 control subjects in total) were used to examine metabolic alterations and identify diagnostic biomarkers. Unbiased multivariate and univariate studies were combined to identify the promising metabolic signatures, based on which the discriminant models for PD were established by integrating multiple machine learning algorithms. A 6-biomarker predictive model was constructed based on the omics profile in the discovery cohort, and the discriminant performance of the biomarker panel was evaluated with an accuracy over 81.6% both in the discovery cohort and validation cohort. The results indicated that PC (40:7), eicosatrienoic acid were negatively correlated with severity of PD, and pentalenic acid, PC (40:6p) and aspartic acid were positively correlated with severity of PD. In summary, we developed a multi-metabolite predictive model which can diagnose PD with over 81.6% accuracy based on this unique metabolic signature. Future clinical diagnosis of PD may benefit from the biomarker panel reported in this study.
The electrocatalytic reduction of nitrate (NO3–) not only facilitates the environmentally sustainable production of ammonia (NH3) but also purifies water by removing NO3–, thereby transforming waste into valuable resources. The process of converting NO3– to NH3 is complex, involving eight electron transfers and multiple intermediates, making the choice of electrocatalyst critical. In this study, we report a cobalt selenide (CoSe2) nanowire array on carbon cloth (CoSe2/CC) as an effective electrocatalyst for the NO3– to NH3 conversion. In an alkaline medium with 0.1 mol/L NO3–, CoSe2/CC demonstrates exceptional NH3 Faradaic efficiency of 97.6% and a high NH3 yield of 517.7 µmol h–1 cm–2 at –0.6 V versus the reversible hydrogen electrode. Furthermore, insights into the reaction mechanism of CoSe2 in the electrocatalytic NO3– reduction are elucidated through density functional theory calculations.
Water-soluble inorganic ions (WSIIs) play a pivotal role in atmospheric chemical reactions, particularly influencing the formation of secondary particulate matter. A comprehensive grasp of the vertical distribution of atmospheric pollutants holds immense significance in understanding the diffusion and transportation of these pollutants. This study investigates the WSIIs of PM2.5 and size-segregated particles at the top (~2060 m a.s.l.) and foot of Mt. Hua during the winter of 2020. All the measured ions present significant higher concentrations (1.9~6.9 times) at the foot than the top. Cl− and K+ at the foot are more than 4 times of those at the top, whereas Ca2+ and Mg2+ are only 1.3–1.9 times higher. The particle size distribution of NO3−, SO42−, K+ and Cl− demonstrate a single peak distribution (0.7–1.1 µm) at the foot, but with a bimodal distribution (0.7–1.1 µm and 4.7–5.8 µm) at the top. These differences suggest that the aerosol at the alpine region is mainly transported via long-distance from Northwest/North China, but limited influenced by vertical transport through valley breeze. The changes of concentration and size distribution of WSIIs in dust event and non-dust period indicate that the effects of dust event on aerosols at ground surface were weaker than that of the free troposphere of Guanzhong Plain. Notably, our study underscores the dominant influence of NO3− in shaping the gas-particle distribution of ammonia within the winter free troposphere. Our results highlight the significant role of long-range transport on aerosols in the free troposphere in Guanzhong Plain, Northwest China.
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