Latest ArticlesSingle atom catalyst (SAC) refers to a novel catalyst with the active metal atoms individually anchored on the support. Single atom catalysts present the unique appeal due to the high atomic availability and specific activity, as well as the high pathway selectivity. Herein, we summarized the classification, preparation, characterization, and application of single atom catalysts. Finally, the current bottlenecks and the outlooks of the SAC research are discussed.
The successful applications of two-dimensional (2D) transition metal dichalcogenides highly rely on rational regulation of their electronic properties. The nondestructive and controllable doping strategy is of great importance to implement 2D materials in electronic devices. Herein, we propose a straightforward and effective method to realize controllable n-type doping in WSe2 monolayer by electron beam irradiation. Electrical measurements and photoluminescence (PL) spectra verify the strong n-doping in electron beam-treated WSe2 monolayers. The n-type doping arises from the generation of Se vacancies and the doping degree is precisely controlled by irradiation fluences. Due to the n-doping-induced narrowing of the Schottky barrier, the current of back-gated monolayer WSe2 is enhanced by an order of magnitude and a ~8 × increase in the electron filed-effect mobility is observed. Remarkably, it is a moderate method without significant reduction in electrical performance and severe damage to lattice structures even under ultra-high doses of irradiation.
The simultaneous removal of SO2, NOx and Hg0 from industrial exhaust flue gas has drawn worldwide attention in recent years. A particularly attractive technique is selective catalytic reduction, which effectively removes SO2, NOx and Hg0 at low temperatures. This paper first reviews the simultaneous removal of SO2, NOx and Hg0 by unsupported and supported catalysts. It then describes and compares the research progress of various carriers, eg., carbon-based materials, metal oxides, silica, molecular sieves, metal-organic frameworks, and pillared interlayered clays, in the simultaneous removal of SO2, NOx and Hg0. The effects of flue-gas components (such as O2, NH3, HCl, H2O, SO2, NO, and Hg0) on the removal of SO2, NOx, and Hg0 are discussed comprehensively and systematically. After summarizing the pollutant-removal mechanism, the review discusses future developments in the simultaneous removal of SO2, NOx and Hg0 by catalysts.
Carbon-based fluorescent nanomaterials have gained much attention in recent years. In this work, green-photoluminescent carbon nanodots (CNDs; also termed carbon dots, CDs) with amine termination were synthesized via the hydrothermal treatment of amine-containing spermine and rose bengal (RB) molecules. The CNDs have an ultrasmall size of ~2.2 nm and present bright photoluminescence with a high quantum yield of ~80% which is possibly attributed to the loss of halogen atoms (Cl and I) during the hydrothermal reaction. Different from most CNDs which have multicolor fluorescence emission, the as-prepared CNDs possess excitation-independent emission property, which can avoid fluorescence overlap with other fluorescent dyes. Moreover, the weakly basic amine-terminated surface endows the CNDs with the acidotropic effect. As a result, the CNDs can accumulate in the acidic lysosomes after cellular internalization and can serve as a favorable agent for lysosome imaging. Besides, the CNDs have a negligible impact on the lysosomal morphology even after 48 h incubation and exhibit excellent biocompatibility in the used cell models.
A facile and efficient strategy was established for the construction of RC-529 and its derivatives. Four conjugates of RC-529 derivatives with Tn antigen were synthesized and all elicited strong and T cell-dependent immune responses in mice without requiring external adjuvants. In addition, all antisera induced by these conjugates could specifically recognize, bind to and kill Tn-overexpressing cancer cells. Thus, RC-529 shows promise as a useful platform for the development of new vaccine carriers with self-adjuvanting properties for the treatment of cancer. Moreover, preliminary structure-activity relationship analysis provides convincing support for further optimization of, and additional investigation into, RC-529.
The research of borate materials as sodium-ion batteries (SIBs) anode is still in the early stages, but the boron polyoxoanions are attracting intense interest due to their low atomic weight and high electronegative features. In this work, FeBO3 was prepared with low-cost raw materials and evaluated as SIBs anode. The FeBO3 shows a high reversible capacity of 328 mAh/g at the current density of 0.4 A/g. In addition, the electrochemical performance of FeBO3 can be improved by carbon coating. The prepared carbon-coated FeBO3 composite has a reversible capacity of 426 mAh/g (at 0.4 A/g) and an outstanding rate capability of 272 mAh/g (at 1.6 A/g). Furthermore, the sodium storage mechanism of FeBO3 was studied by in-situ XRD and ex-situ XPS.
Durability is one of the critical issues to restrict the commercialization of proton exchange membrane fuel cells (PEMFCs) for the vehicle application. The practical dynamic operation significantly affects the PEMFCs durability by corroding its key components. In this work, the degradation behavior of a single PEMFC has been investigated under a simulated automotive load-cycling operation, with the aim of revealing the effect of load amplitude (0.8 and 0.2 A/cm2 amplitude for the current density range of 0.1−0.9 and 0.1−0.3 A/cm2, respectively) on its performance degradation. A more severe degradation on the fuel cell performance is observed under a higher load amplitude of 0.8 A/cm2 cycling operation, with ~10.5% decrease of cell voltage at a current density of 1.0 A/cm2. The larger loss of fuel cell performance under the higher load amplitude test is mainly due to the frequent fluctuation of a wider potential cycling. Physicochemical characterizations analyses indicate that the Pt nanoparticles in cathodic catalyst layer grow faster with a higher increase extent of particle size under this circumstance because of their repeated oxidation/reduction and subsequent dissolution/agglomeration process, resulting in the degradation of platinum catalyst and thus the cell performance. Additionally, the detected microstructure change of the cathodic catalyst layer also contributes to the performance failure that causes a distinct increase in mass transfer resistance.
Metal–organic frameworks (MOFs) have a regular porous structure and high porosity, which make them ideal electrode materials for supercapacitors. However, their capacitance performance is greatly limited by their poor conductivity. In this study, a multi-component hierarchical structure was obtained by growing NiCoFeLDH on the surface of ZIF-67, which increased the electron transfer between the MOF particles and greatly improved the capacitance of ZIF-67. The formation mechanism of the multi-component layered hollow structure indicated that the hydrolysis acidity of metal ions and the coordination ability with ligands were the key factors for forming nanosheets and hollow structures. By controlling the type and valence state of the doped metals and the reaction time, the morphology transformation of MOF composites can be effectively controlled. Electrochemical studies showed that the specific capacitance of hollow NiCoFeLDH@ZIF-67 composite is 1202.08F/g (0.5 A/g). In addition, aqueous devices were assembled and carefully tested. This scheme is crucial for the design of MOF-based materials used in supercapacitor devices and serves as a guide for the design of MOF-based composites.
We have developed a versatile, mild protocol for trifluoromethylthiolation reactions of aldehydes with catalysis by a decatungstate hydrogen atom transfer photocatalyst under redox-neutral conditions. The protocol is highly selective, operationally simple, and compatible with a wide array of sensitive functional groups. It can be used for late-stage functionalization of bioactive molecules, which makes it convenient for drug discovery.
Advanced chemotherapy strategies are in urgent demand for improving anticancer efficacy. Herein, a water-soluble pillar[6]arene (WP6A) was used to load chemotherapeutic agent pemetrexed (PMX) by forming direct host-guest inclusion, which is beneficial for decreasing cytotoxicity of PMX on BEAS-2B cells. NMR and florescence titration served to confirm the complexation between WP6A and ATP with higher affinity [(5.67 ± 0.31) × 105 L/mol], favoring competitive replacement of PMX. Complexation ATP by WP6A effectively prevented ATP from being hydrolyzed in presence of alkaline phosphatase. The formed host-guest complex was further used to block the efflux pump by cutting off energy source from ATP hydrolysis, which was accompanied with releasing PMX to produce synergistic enhancement of anticancer performance towards A549 cells. This supramolecular strategy would also be extended to other clinical chemotherapeutic agents and it was expected to provide salutary profits for cancer patients.