The development of an effective one‐photon excitation pathway to improve the charge‐carrier separation and mobility of semiconductors, which have been proven to be favorable for heterogeneous ...catalysis, is highly desirable but remains a great challenge. Herein, a high‐throughput one‐photon excitation pathway is reported by constructing 0D carbon dots/3D porous carbon nitride nanovesicles (denoted as CDs/PCN NVs) heterostructures for photocatalytic hydrogen evolution. In particular, the optimum CDs/PCN NVs heterostructures exhibit an impressive performance of 14.022 mmol h−1 g−1, which is 56.54 times higher than that of pristine CN. Detailed characterization reveals that the improved performance is primarily attributed to the high‐throughput and one‐photon excitation pathway. The former could be attributed to a great deal of CDs with high charge‐carrier mobility coupled to PCN NVs, which enable more electrons to be photoexcited via the broad absorption response, and the multiple reflection of incident light owing to the porous nanovesicle structure with shortened route of carriers migrating toward the surface; the latter would lead to the photoinduced holes and electrons accumulated at the valence band of PCN NVs and surface of CDs, respectively, achieving an effective spatial separation. The high‐throughput one‐photon excitation pathway demonstrated here may provide insights into the development of nanocomposites for various related applications.
A high‐throughput one‐photon excitation pathway is reported by constructing 0D carbon dots/3D porous carbon nitride nanovesicles (CDs/PCN NVs) heterostructures for visible‐light driven hydrogen evolution. In particular, the covalently bonded CDs on PCN NVs enable a high throughput charge migration in the wide spectrum visible light region and promote effective spatial separation via a one‐photon excitation pathway.
2D amorphous transition metal oxides (a‐TMOs) heterojunctions that have the synergistic effects of interface (efficiently promoting the separation of electron−hole pairs) and amorphous nature ...(abundant defects and dangling bonds) have attracted substantial interest as compelling photocatalysts for solar energy conversion. Strategies to facilely construct a‐TMOs‐based 2D/2D heterojunctions is still a big challenge due to the difficulty of preparing individual amorphous counterparts. A generalized synthesis strategy based on supramolecular self‐assembly for bottom–up growth of a‐TMOs‐based 2D heterojunctions is reported, by taking 2D/2D g‐C3N4 (CN)/a‐TMOs heterojunction as a proof‐of‐concept. This strategy primarily depends on controlling the cooperation of the growth of supramolecular precursor and the coordinated covalent bonds arising from the tendency of metal ions to attain the stable configuration of electrons, which is independent on the intrinsic character of individual metal ion, indicating it is universally applicable. As a demonstration, the structure, physical properties, and photocatalytic water‐splitting performance of CN/a‐ZnO heterojunction are systematically studied. The optimized 2D/2D CN/a‐ZnO exhibits enhanced photocatalytic performance, the hydrogen (432.6 µmol h−1 g−1) and oxygen (532.4 µmol h−1 g−1) evolution rate are 15.5 and 12.2 times than bulk CN, respectively. This synthetic strategy is useful to construct 2D a‐TMOs nanomaterials for applications in energy‐related areas and beyond.
A generalized synthesis strategy for the bottom–up growth of amorphous transition metal oxides (a‐TMOs) 2D/2D heterojunctions with large contact area via covalent interfacial interaction is provided. A number of 2D/2D CN/a‐TMOs heterojunctions, such as CN/a‐FeOx, CN/a‐CuOx, CN/a‐MnOx, CN/a‐CoOx, and CN/a‐ZnO are successfully synthesized, which has a large and perfect order−disorder interface. Particularly, 2D/2D CN/a‐ZnO heterojunction exhibit boosted photocatalytic hydrogen and oxygen evolution.
Recent progress in the ZnO nanostructure-based sensors Wei, Ang; Pan, Liuhua; Huang, Wei
Materials science & engineering. B, Solid-state materials for advanced technology,
11/2011, Letnik:
176, Številka:
18
Journal Article
Recenzirano
This review focuses on the sensors based on zinc oxide (ZnO) nanostructures, which have fascinating properties including large specific surface area, good biocompatibility, high electron mobility and ...piezoelectricity. Due to these versatile characteristics, ZnO nanostructures can be based upon to construct gas sensors, chemical sensors, biosensors, UV sensors, pH sensors and other sensors with different sensing mechanisms. The main structures of the sensors and factors influencing the sensitivity are also discussed.
Helicobacter pylori is recognised as a main risk factor for gastric cancer. However, approximately half of the patients with gastritis are negative for H. pylori infection, and the abundance of H. ...pylori decreases in patients with cancer. In the current study, we profiled gastric epithelium-associated bacterial species in patients with gastritis, intestinal metaplasia, and gastric cancer to identify additional potential pathogenic bacteria. The overall composition of the microbiota was similar between the patients with gastritis and those with intestinal metaplasia. H. pylori was present in half of the non-cancer group, and the dominant bacterial species in the H. pylori-negative patients were Burkholderia, Enterobacter, and Leclercia. The abundance of those bacteria was similar between the cancer and non-cancer groups, whereas the frequency and abundance of H. pylori were significantly lower in the cancer group. Instead, Clostridium, Fusobacterium, and Lactobacillus species were frequently abundant in patients with gastric cancer, demonstrating a gastric cancer-specific bacterial signature. A receiver operating characteristic curve analysis showed that Clostridium colicanis and Fusobacterium nucleatum exhibited a diagnostic ability for gastric cancer. Our findings indicate that the gastric microenvironment is frequently colonised by Clostridium and Fusobacterium in patients with gastric cancer.
Herein we present a new viologen‐based radical‐containing metal–organic framework (RMOF) Gd‐IHEP‐7, which upon heating in air undergoes a single‐crystal‐to‐single‐crystal transformation to generate ...Gd‐IHEP‐8. Both RMOFs exhibit excellent air and water stability as a result of favorable radical‐radical interactions, and their long‐lifetime radicals result in wide spectral absorption in the range 200–2500 nm. Gd‐IHEP‐7 and Gd‐IHEP‐8 show excellent activity toward solar‐driven nitrogen fixation, with ammonia production rates of 128 and 220 μmol h−1 g−1, respectively. Experiments and theoretical calculations indicate that both RMOFs have similar nitrogen fixation pathways. The enhanced catalytic efficiency of Gd‐IHEP‐8 versus Gd‐IHEP‐7 is attributed to intermediates stabilized by enhanced hydrogen bonding.
A single‐crystal‐to‐single‐crystal (SCSC) transformation of stable radical‐containing MOF Gd‐IHEP‐7 generates Gd‐IHEP‐8. It is accompanied by a marked increase in efficiency of sacrificial agent‐free photocatalytic nitrogen fixation to yield NH3 from H2O and N2 under simulated solar light irradiation at ambient temperature. The NH3 production rate of 220 μmol h−1 g−1 for Gd‐IHEP‐8 is a new record for MOF photocatalysts.
The tumor microenvironment is a highly complex ecosystem of diverse cell types, which shape cancer biology and impact the responsiveness to therapy. Here, we analyze the microenvironment of ...esophageal squamous cell carcinoma (ESCC) using single-cell transcriptome sequencing in 62,161 cells from blood, adjacent nonmalignant and matched tumor samples from 11 ESCC patients. We uncover heterogeneity in most cell types of the ESCC stroma, particularly in the fibroblast and immune cell compartments. We identify a tumor-specific subset of CST1
myofibroblasts with prognostic values and potential biological significance. CST1
myofibroblasts are also highly tumor-specific in other cancer types. Additionally, a subset of antigen-presenting fibroblasts is revealed and validated. Analyses of myeloid and T lymphoid lineages highlight the immunosuppressive nature of the ESCC microenvironment, and identify cancer-specific expression of immune checkpoint inhibitors. This work establishes a rich resource of stromal cell types of the ESCC microenvironment for further understanding of ESCC biology.
Organic–inorganic hybrid halide perovskites (e.g., MAPbI3) have recently emerged as novel active materials for photovoltaic applications with power conversion efficiency over 22%. Conventional ...perovskite solar cells (PSCs); however, suffer the issue that lead is toxic to the environment and organisms for a long time and is hard to excrete from the body. Therefore, it is imperative to find environmentally‐friendly metal ions to replace lead for the further development of PSCs. Previous work has demonstrated that Sn, Ge, Cu, Bi, and Sb ions could be used as alternative ions in perovskite configurations to form a new environmentally‐friendly lead‐free perovskite structure. Here, we review recent progress on lead‐free PSCs in terms of the theoretical insight and experimental explorations of the crystal structure of lead‐free perovskite, thin film deposition, and device performance. We also discuss the importance of obtaining further understanding of the fundamental properties of lead‐free hybrid perovskites, especially those related to photophysics.
Recent progress on lead‐free perovskite solar cells (PSCs) in terms of the theoretical insight and experimental explorations of the crystal structure of lead‐free perovskites, thin‐film deposition, and device performance is reviewed. The importance of understanding the fundamental properties of lead‐free hybrid perovskites is discussed. Greater effort is needed to explore high‐performance lead‐free PSCs.
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•Ultra-thin tubular porous CN/C-Dots LHSs were successfully fabricated.•CN/C-Dots LHSs are nearly perfect nanotubes with wall thickness of about 8.0 nm.•CN/C-Dots LHSs is demonstrated ...to enhance the charge carriers transport of CN.•The ultra-efficient HER activity of 24,760 μmol h−1 g−1 and AQY of 21.2% are achieved.
Lateral heterostructures (LHSs) consisting of two-dimensional (2D) layered materials are generally nanosheets that are unfavourable to various applications, such as photocatalysis, because they are prone to agglomerate and against for multiple absorption and utilization of light. Herein, for the first time, we prepare ultra-thin tubular LHSs of graphitic carbon nitride and carbon dots (CN/C-Dots), with thickness of ~8.0 nm via a facile, one-step thermal polymerization of the supramolecular complexes composed of melamine, cyanuric acid and β-cyclodextrin (β-CyD) as starting monomers. Interestingly, the structural topology of the CN/C-Dots LHSs can be effectively modulated by the amount of β-CyD. The obtained tubular porous LHSs are nearly perfect nanotubes with wall thickness of about 8.0 nm, the smallest one reported so far, which not only greatly increases the accessibility of active sites and light harvesting via high light absorption and scattering, but also shortens the route of carriers migrating towards the surface and improves the mass transport. In comparison with CN, the optimized ultra-thin tubular porous CN/C-Dots100 LHSs exhibit significantly boosted visible light photocatalytic hydrogen evolution activity (up to 113 times) of 24,760 μmol h−1 g−1 (λ > 420 nm), much higher than that over pure or nonmetal modified CN tubes reported to date. Moreover, the tubular porous CN/C-Dots100 LHSs are first demonstrated to be excellent electrocatalysts for hydrogen evolution reaction (HER) and oxgen evolution reaction (OER), achieving a geometrical catalytic current density of 10 mA cm−2 at overpotentials 415 and 340 mV in 0.5 M H2SO4 and 1 M KOH versus the reversible hydrogen electrode (RHE), respectively. These findings may provide insights into constructing highly efficient catalysts by tuning structural topology and heterojunction for different energy-related applications.
The effects of chordwise deformation and the half-amplitude asymmetry on the hydrodynamic performance and vortex dynamics of batoid fish have been numerically investigated, in which the two ...parameters were represented by the wavenumber ($W$) and the ratio of the half-amplitude above the longitudinal axis to that below ($HAR$). Fin kinematics were prescribed based on biological data. Simulations were conducted using the immersed boundary method. It was found that moderate chordwise deformation enhances the thrust, saves the power and increases the efficiency. A large $HAR$ can also increase thrust performance. By using the derivative-moment transformation theory at several subdomains to capture the local vortical structures and a force decomposition, it was shown that, at high Strouhal numbers ($St$), the tip vortex is the main source of thrust, whereas the leading-edge vortex (LEV) and trailing-edge vortex weaken the thrust generation. However, at lower $St$, the LEV would enhance the thrust. The least deformation ($W=0$) leads to the largest effective angle of attack, and thus the strongest vortices. However, moderate deformation ($W=0.4$) has an optimal balance between the performance enhancement and the opposite effect of different local structures. The performance enhancement of $HAR$ was also due to the increase of the vortical contributions. This work provides a new insight into the role of vortices and the force enhancement mechanism in aquatic swimming.
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