Latest ArticlesThe catalytic performance of light-derived CO2 reduction with H2O is strongly dependent on the separation efficiency of photogenerated carriers. Herein, the direct Z-scheme catalysts (g-C3N4/3DOM-WO3) of graphitic carbon nitride (g-C3N4) nanosheets decorated three-dimensional ordered macroporous WO3 (3DOM-WO3) were successfully fabricated by using the in-situ colloidal crystal template method. The slow light effect of 3DOM-WO3 photonic crystals expands the absorption of visible light and improves the utilization of light energy. The Z-scheme structure of g-C3N4/3DOM-WO3 catalysts is able to upgrade the separation efficiency of photogenerated electron-hole pairs. The g-C3N4/3DOM-WO3 photocatalyst, whose formation rate of CO product is 48.7 μmol g−1 h−1, exhibits the excellent catalytic activity for CO2 reduction. The transfer pathway of stimulated electrons over the g-C3N4/3DOM-WO3 photocatalyst is proposed and discussed. The present approach provides unique insights into the rational development of high-performance photochemical systems for efficient CO2 reduction into valuable carbon-containing chemicals and energy fuels.
The recombination of charge carriers arriving from the random charge movement in semiconductor photocatalysts greatly limits the practical application of solar-driven H2 evolution. The design of photocatalytic systems with spatially oriented charge-transfer is a promising route to achieve high charge-separation efficiency for photocatalysts. Herein, novel sea-urchin-like ReS2 nanosheet/TiO2 nanoparticle heterojunctions (SURTHs) are constructed. The unique sea-urchin-like structure endows the ReS2 cocatalyst with an unusual charge edge-collection effect, which leads to a significant acceleration of charge separation and transfer, as evidenced by the well-designed selective photodeposition of Pt quantum dots in SURTHs. The markedly improved charge transfer capacity contributes to a high photocatalytic H2 evolution rate of 3.71 mmol h-1 g-1 for SURTHs (an apparent quantum efficiency (AQE) of 16.09%), up to 231.9 times by contrast with that of P25 TiO2. This work would provide a new platform for designing the high-efficiency cocatalyst/photocatalyst system with excellent charge transfer capacity.
In this study, natural mackinawite (FeS), a chalcophilic mineral, was utilized to prepare iron/copper bimetallic oxides (CuO@FexOy) by displacement plating and calcination process. Various characterization methods prove that Cu0 is successfully coated on the surface of FeS, which were further oxidized to CuO, Fe3O4 and/or Fe2O3 during calcination process, respectively. CuO@FexOy performed highly efficient capacity to activate PMS for the degradation of various emerging pollutants including sulfamethoxazole (SMX), carbamazepine (CBZ), bisphenol A (BPA), 2, 4-dichlorophenol (2, 4-DCP) and diclofenac (DCF) in aqueous solution. Complete removal of the above pollutants was observed after 8 min of CuO@FexOy/PMS treatment. Taking SMX as an example, the key parameters including CuO@FexOy dosage, PMS dosage and initial pH were optimized. The results show that the catalytic system can be worked in a wide pH range (3.0-9.0). The quenching experiments and electron spin resonance (ESR) test demonstrated that the main reactive oxygen species in CuO@FexOy/PMS system were hydroxyl radicals (•OH) and sulfate radicals (SO4•–), and SO4•– was the primary reactive species. Besides, the influence of coexisting anions (i.e., Cl–, NO3–, HCO3– and H2PO4–) for the degradation of SMX was explored. CuO@FexOy/PMS system can maintain good catalytic activity and reusability in different water bodies and long-term running. This work provided a green strategy to fabricate the efficient catalyst in PMS-based advanced oxidation processes.
Recovering critical metals from secondary resources have attracted great interest recently. In this work, a green one-pot leaching-extraction process based on tributyl(tetradecyl)phosphonium chloride (P44414Cl) aqueous biphasic system (ABS) was developed to efficiently recover rare earth elements (REEs) from NdFeB permanent magnet. The reaction process, phase separation mechanism, and operation conditions were thoroughly investigated. It is found that the P44414Cl-HCl ABS showed strong extraction ability towards Fe (> 99%) whereas only a few REEs (< 10%) were extracted, leading to extremely high separation selectivity between Fe and REEs. The characterization results showed that the coordination differences of Fe and Nd in HCl were the main driving forces for such highly selective separation. The phase diagram of P44414Cl-NdCl3 ABS indicated that the salting-out effect of NdCl3 was stronger than common chlorides. Due to the hydrophobic property of P44414[FeCl4] and salting-out effect of NdCl3, the P44414Cl could directly form ABS at room temperature after dissolving practical roasted NdFeB samples without any other operations and reagents. REEs and Fe could be mutually separated in just one step. Compared with traditional liquid-liquid extraction or ABS separation, this recovery process is green and facile and shows great application prospects in the field of rare-earth recovery.
Various advanced microwave absorbing materials have been developed for reducing/avoiding the harm of microwave radiation. Among them, core-shell structural nanomaterials have been widely fabricated for microwave absorption. However, the "structure-performance" relationship between shell thickness and microwave absorption performance is rarely reported. In this paper, we first explored the "structure-performance" relationship between shell thickness and microwave absorption performance, based on the core-shell α-Fe2O3@SiO2 nanoparticles with a constant α-Fe2O3-core size and changeable SiO2-shell thickness. With increasing the SiO2-shell thickness, the microwave absorption ability first increased, then decreased. Under a proper SiO2-shell thickness of 35 nm, α-Fe2O3@SiO2 sample achieved the strongest microwave absorbing ability with a reflection loss minimum value of –4.3 dB, better than that of pure α-Fe2O3 (–3.8 dB). This enhanced microwave absorption performance was mainly derived from the dielectric loss. Although the absolute value of the reflection loss was relatively low (–4.3 dB), this study shed an important reference on designing next-generation advanced iron oxide-based materials for microwave absorption.
The waxberry-like mixed-phase TiO2 hollow microstructures (WMTHMs) are controllably prepared via a topotactic synthetic method, involving the synthesis of monodispersed CaTiO3 precursors by a solvothermal method and subsequently transforming them into TiO2 through a Na2EDTA-assisted ion-exchange process. The ratio of anatase-rutile is adjustable, and the two phases are connected well with each other. WMTHMs are composed of radially aligned nanorods, speeding up the electron transport. The optimum WMTHMs sample shows a specific surface area of 68.05 m2/g and exhibits an excellent light scattering capacity. The cell based on WMTHMs light scattering layer obtained an optimal efficiency of 9.12%. The improvement of cell efficiency is mainly attributed to the high specific surface area, the efficient light scattering, the appropriate ratio of anatase-rutile, the staggered bandgap structure, and the convenient one-dimensional electron transport channel.
A reliable and sensitive strategy which can assess nucleic acid levels in living cells would be essential for fundamental research of biomedical applications. Some nanomaterial-based fluorescence biosensors recently developed for detecting nucleic acids, however, are often with expensive, complicated and time-consuming preparation process. Here, by using a facile bottom-up synthesis method, a two-dimensional (2D) coordination polymer (CP) nanosheet, [Cu(tz)] (Htz = 1, 2, 4-triazole), was successfully prepared after optimizing reaction conditions. These ultrathin CP nanosheets with thickness of 4.7 ± 1.1 nm could readily form nanosensors by assembly with DNA probes, which exhibited a low limit of detection (LOD) for p53 DNA fragment as 144 pmol/L. Furthermore, by integrating [Cu(tz)] nanosheets with hybridization chain reaction (HCR) probes, miR-21, one kind of microRNA upregulated in many cancer cells, can be sensitively detected with a LOD of 100 pmol/L and monitored in living cells, giving consistent results with those obtained by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis. Thus [Cu(tz)] nanosheets, which not only possess much better nucleic acids sensing performance than bulk cystals, but also exhibit nucleic acid delivery functions, could be used as a novel nanoplatform in biomedical imaging and sensing applications.
A novel copper-based MOFs adsorbent (Cu-BTC-Th) was prepared using an one-step method by introducing a new organic ligand of 4-thioureidobenzoicacid (Th) with active groups for selectively adsorbing Pb(Ⅱ) from aqueous solutions. The chemical composition and structure of the prepared MOFs materials were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Brunner−Emmet−Teller (BET) analysis, and zeta potential measurements. The adsorption capability of the prepared Cu-MOFs was significantly enhanced by introducing the new organic ligand of Th in the materials. The maximum adsorption capacity of the Cu-BTC-Th for Pb(Ⅱ) attains 732.86 mg/g under the optimal conditions. In addition, the adsorption kinetics and adsorption isotherm analysis showed that the adsorption process followed the pseudo-second-order kinetic model and Langmuir adsorption model, indicating that the adsorption of Pb(Ⅱ) by Cu-BTC-Th was a monolayer chemisorption. The adsorption mechanism of Cu-BTC-Th for Pb(Ⅱ) was discussed and revealed. On one hand, the adsorption of Pb(Ⅱ) is mainly through ion exchange with the Cu(Ⅱ). On the other hand, the −NH2 and −C=S functional groups introduced in the Cu-BTC-Th materials have stronger coordination ability with the Pb(Ⅱ) ions to enhance the adsorption capability.
Bladder cancer is the most common malignant tumours with high morbidity, mortality and recurrence. However, currently developed detection methods for bladder cancer-associated urine biomarkers are hindered by their extremely low abundance. Hence, the exploration of a highly sensitive and selective approach for the detection of trace bladder cancer-associated biomarkers in human urine is of vital importance for the diagnosis of bladder cancer. Herein, we developed a highly reliable indium gallium zinc oxide field effect transistor (IGZO FET) biosensor for the detection of bladder cancer-related biomarker microRNA. The single-stranded DNA-functionalized IGZO FET biosensors exhibit high sensing reproducibility and stability with an ultralow detection limit of 19.8 amol/L. The device could also be used for quantitative detection of trace microRNA in human urine samples and can effectively distinguish bladder cancer patients from healthy donors. The development of high performance IGZO FET biosensors presents new opportunities for the achievement of early-stage diagnosis of bladder cancer.
Photoelectrochemical (PEC) sensor is an emerging technology in analysis as the advantage of fast response, high sensitivity and uncomplicated operation. In this study, an effective label-free PEC sensor for bisphenol A (BPA) detecting is constructed, in which ZnIn2S4/g-C3N4 heterojunction is prepared via a simple hydrothermal method. The characterization outcomes display that the formation of p-n heterojunction helps for promoting the separation efficiency of photo-generated carrier. Under visible light irradiation, the ZnIn2S4/g-C3N4 modified electrode exhibits broader liner range from 0.05 mmol/L to 30 mmol/L and lower detection limit of 0.016 µmol/L (S/N = 3) with remarkable stability and reproducibility of detection BPA under visible light irradiation. Furthermore, the constructed PEC sensor displays favorable potential for detection of BPA in practical applications.
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