Organic–inorganic hybrid two-dimensional (2D) perovskites have recently attracted great attention in optical and optoelectronic applications due to their inherent natural quantum-well structure. We ...report the growth of high-quality millimeter-sized single crystals belonging to homologous two-dimensional (2D) hybrid organic–inorganic Ruddelsden–Popper perovskites (RPPs) of (BA)2(MA) n −1Pb n I3 n +1 (n = 1, 2, and 3) by a slow evaporation at a constant-temperature (SECT) solution-growth strategy. The as-grown 2D hybrid perovskite single crystals exhibit excellent crystallinity, phase purity, and spectral uniformity. Low-threshold lasing behaviors with different emission wavelengths at room temperature have been observed from the homologous 2D hybrid RPP single crystals. Our result demonstrates that solution-growth homologous organic–inorganic hybrid 2D perovskite single crystals open up a new window as a promising candidate for optical gain media.
Coupling urea oxidation reaction (UOR) with hydrogen evolution reaction (HER) is an effective energy‐saving technique for hydrogen generation. However, exploring efficient bifunctional ...electrocatalysts under high current density is still challenging. Herein, hierarchical Fe doped cobalt selenide coupled with FeCo layered double hydroxide (Fe‐Co0.85Se/FeCo LDH) array as a self‐supported superior bifunctional heterojunction electrode is rationally designed for both UOR and HER. The unique heterostructure facilitates electron transfer and interface interactions through local interfacial Co‐Se/O‐Fe bonding environment modulation, improving reaction kinetics and intrinsic activity. As a result, the heterostructured electrocatalyst exhibits ultralow potentials of −0.274 and 1.48 V to reach 500 mA cm−2 for catalyzing the HER and UOR, respectively. Particularly, the full urea electrolysis system driven by Fe‐Co0.85Se/FeCo LDH delivers 300 mA cm−2 at a relatively low potential of 1.57 V, which is 150 mV lower than the conventional water electrolysis. The combination of in situ characterization and theoretical analysis reveal that the active sites with the adjustable electronic environment are induced by the interfacial bonding of the heterojunction, facilitating the water decomposition of HER and the stabilization of intermediates in UOR. This work inspires the interfacial environment modulation to optimize advanced electrocatalysts for energy‐saving H2 production.
The heterostructure constructed by Fe doped Co0.85Se and FeCo LDH can induce the modulation of local interfacial bonding environment and optimize the d‐band center to benefit the intermediates adsorption/desorption during urea oxidation reaction. As a result, a low cell voltage of 1.57 V at 300 mA cm−2 for urea water splitting is achieved based on the heterostructure.
Designing well‐defined interfacial chemical bond bridges is an effective strategy to optimize the catalytic activity of metal–organic frameworks (MOFs), but it remains challenging. Herein, a facile ...in situ growth strategy is reported for the synthesis of tightly connected 2D/2D heterostructures by coupling MXene with CoBDC nanosheets. The multifunctional MXene nanosheets with high conductivity and ideal hydrophilicity as bridging carriers can ensure structural stability and sufficient exposure to active sites. Moreover, the Co–O–Ti bond bridging formed at the interface effectively triggers the charge transfer and modulates the electronic structure of the Co‐active site, which enhances the reaction kinetics. As a result, the optimized CoBDC/MXene exhibits superior hydrogen evolution reaction (HER) activity with low overpotentials of 29, 41, and 76 mV at 10 mA cm−2 in alkaline, acidic, and neutral electrolytes, respectively, which is comparable to commercial Pt/C. Theoretical calculation demonstrates that the interfacial bridging‐induced electron redistribution optimizes the free energy of water dissociation and hydrogen adsorption, resulting in improved hydrogen evolution. This study not only provides a novel electrocatalyst for efficient HER at all pH conditions but also opens up a new avenue for designing highly active catalytic systems.
A novel CoBDC/MXene electrocatalyst with 2D/2D heterostructure is prepared by a facile in situ growth strategy, in which the formation of interfacial Co–O–Ti bridges effectively tunes the electron distribution and catalytic reaction energy barrier, leading to ultralow hydrogen evolution reaction overpotentials at all pH conditions.
An optimal single-photon source should deterministically deliver one, and only one, photon at a time, with no trade-off between the source’s efficiency and the photon indistinguishability. However, ...all reported solid-state sources of indistinguishable single photons had to rely on polarization filtering, which reduced the efficiency by 50%, fundamentally limiting the scaling of photonic quantum technologies. Here, we overcome this long-standing challenge by coherently driving quantum dots deterministically coupled to polarization-selective Purcell microcavities. We present two examples: narrowband, elliptical micropillars and broadband, elliptical Bragg gratings. A polarization-orthogonal excitation–collection scheme is designed to minimize the polarization filtering loss under resonant excitation. We demonstrate a polarized single-photon efficiency of 0.60 ± 0.02 (0.56 ± 0.02), a single-photon purity of 0.975 ± 0.005 (0.991 ± 0.003) and an indistinguishability of 0.975 ± 0.006 (0.951 ± 0.005) for the micropillar (Bragg grating) device. Our work provides promising solutions for truly optimal single-photon sources combining near-unity indistinguishability and near-unity system efficiency simultaneously.
To report long‐term results of a randomized controlled trial that compared cisplatin/fluorouracil/docetaxel (TPF) induction chemotherapy (IC) plus concurrent chemoradiotherapy (CCRT) with CCRT alone ...in locoregionally advanced nasopharyngeal carcinoma (NPC). Patients with stage III–IVB (except T3–4 N0) NPC were randomly assigned to receive IC plus CCRT (n = 241) or CCRT alone (n = 239). IC included three cycles of docetaxel (60 mg/m2 d1), cisplatin (60 mg/m2 d1), and fluorouracil (600 mg/m2/d civ d1–5) every 3 weeks. Patients from both groups received intensity‐modulated radiotherapy concurrently with three cycles of 100 mg/m2 cisplatin every 3 weeks. After a median follow‐up of 71.5 months, the IC plus CCRT group showed significantly better 5‐year failure‐free survival (FFS, 77.4% vs. 66.4%, p = 0.019), overall survival (OS, 85.6% vs. 77.7%, p = 0.042), distant failure‐free survival (88% vs. 79.8%, p = 0.030), and locoregional failure‐free survival (90.7% vs. 83.8%, p = 0.044) compared to the CCRT alone group. Post hoc subgroup analyses revealed that beneficial effects on FFS were primarily observed in patients with N1, stage IVA, pretreatment lactate dehydrogenase ≥170 U/l, or pretreatment plasma Epstein–Barr virus DNA ≥6000 copies/mL. Two nomograms were further developed to predict the potential FFS and OS benefit of TPF IC. The incidence of grade 3 or 4 late toxicities was 8.8% (21/239) in the IC plus CCRT group and 9.2% (22/238) in the CCRT alone group. Long‐term follow‐up confirmed that TPF IC plus CCRT significantly improved survival in locoregionally advanced NPC with no marked increase in late toxicities and could be an option of treatment for these patients.
What's new?
Despite advances in the treatment of nasopharyngeal carcinoma, approximately 30% of high‐risk patients experience recurrence after treatment. Here the authors find that combining the conventional chemoradiotherapy with a triple induction chemotherapy (cisplatin/fluorouracil/docetaxel) prolonged survival of patients with locoregionally advanced cancer, even after more than 70 months of follow‐up. The combination treatment increased acute, but not late, toxicities, and the authors propose that it could present a new treatment option for this patient group.
Hierarchical tubular structures composed of Co3O4 hollow nanoparticles and carbon nanotubes (CNTs) have been synthesized by an efficient multi‐step route. Starting from polymer‐cobalt acetate ...(Co(Ac)2) composite nanofibers, uniform polymer‐Co(Ac)2@zeolitic imidazolate framework‐67 (ZIF‐67) core–shell nanofibers are first synthesized via partial phase transformation with 2‐methylimidazole in ethanol. After the selective dissolution of polymer‐Co(Ac)2 cores, the resulting ZIF‐67 tubular structures can be converted into hierarchical CNTs/Co‐carbon hybrids by annealing in Ar/H2 atmosphere. Finally, the hierarchical CNT/Co3O4 microtubes are obtained by a subsequent thermal treatment in air. Impressively, the as‐prepared nanocomposite delivers a high reversible capacity of 1281 mAh g−1 at 0.1 A g−1 with exceptional rate capability and long cycle life over 200 cycles as an anode material for lithium‐ion batteries.
Forming hierarchies: Hierarchical tubular structures composed of Co3O4 hollow nanoparticles and carbon nanotubes are synthesized from the polymer/cobalt acetate composite nanofibers. Benefiting from unique structural and compositional features, the as‐synthesized hierarchical tubular structures show excellent lithium storage properties.
Anodic organic upgrading offers a promising strategy to produce value-added chemicals and to facilitate coupled hydrogen production but it is still challenging in terms of long-term stability and ...high activity of the electrocatalysts at large current densities. Herein, highly dispersed FeNi oxide heterojunctions anchored on nickel foam (Fe
2
O
3
/NiO) as efficient catalysts are synthesized
via
an ultrafast solution combustion strategy. In methanol electrooxidation, a large absolute current density (500 mA cm
2
at 1.654 V
vs.
RHE) with a high faradaic efficiency (>98%) is achieved.
In situ
infrared spectroscopy and theoretical calculations indicate that the heterostructure modulates the electronic state of NiO through strong electronic interactions, providing unique collaborative active sites for the favorable dynamic conversion of methanol to formate and inhibiting further oxidation. Furthermore, the interface confinement effect also stabilizes the metastable nickel active site, which ensures the stability of the catalyst structure during the reversible redox cycling, resulting in a steady and dynamically-enhanced catalytic process.
The ultrafast solution combustion synthesis of heterogeneous interface is developed to boost anodic organic upgrading reaction, which exhibits remarkable current density and faradaic efficiency benefiting from the strong electronic interaction.
Highly-efficient oxygen evolution reaction (OER) and reduction of carbon dioxide (CO 2 RR) represent the two biggest scientific challenges in artificial photosynthesis. Many efficient and ...cost-affordable electrocatalysts have been reported in the development of electrochemical OER and CO 2 RR; however, during the electro-derived oxidation or reduction processes, a critical fact that, most catalysts tend to undergo structural reconstruction and/or surface rearrangement, has been widely observed, which greatly subverts the traditional conception of “catalysts”. In this respect, the research trends have gradually transferred from optimizing catalyst materials to elucidating the real active sites of the catalysts as well as understanding the underlying mechanisms behind these complex reactions. Most importantly, the in situ / operando characterization techniques are powerful tools to achieve this goal. Herein, recent advances in the in situ X-ray diffraction and absorption spectroscopy that have provided a unique opportunity to investigate the structural reconstruction and/or surface rearrangement of catalysts under realistic OER and CO 2 RR conditions are thoroughly reviewed. Finally, the challenges of the material design are discussed, and the future perspective for developing next-generation catalysts with imperative requirements of material nature is provided.
Palladium diselenide (PdSe2), a peculiar noble metal dichalcogenide, has emerged as a new two-dimensional material with high predicted carrier mobility and a widely tunable band gap for device ...applications. The inherent in-plane anisotropy endowed by the pentagonal structure further renders PdSe2 promising for novel electronic, photonic, and thermoelectric applications. However, the direct synthesis of few-layer PdSe2 is still challenging and rarely reported. Here, we demonstrate that few-layer, single-crystal PdSe2 flakes can be synthesized at a relatively low growth temperature (300 °C) on sapphire substrates using low-pressure chemical vapor deposition (CVD). The well-defined rectangular domain shape and precisely determined layer number of the CVD-grown PdSe2 enable us to investigate their layer-dependent and in-plane anisotropic properties. The experimentally determined layer-dependent band gap shrinkage combined with first-principle calculations suggest that the interlayer interaction is weaker in few-layer PdSe2 in comparison with that in bulk crystals. Field-effect transistors based on the CVD-grown PdSe2 also show performances comparable to those based on exfoliated samples. The low-temperature synthesis method reported here provides a feasible approach to fabricate high-quality few-layer PdSe2 for device applications.
Biological ion channels are known as membrane proteins which can turn on and off under environmental stimulus to regulate ion transport and energy conversion. Rapid progress made in biological ion ...channels provides inspiration for developing artificial nanochannels to mimic the structures and functions of ion transport systems and energy conversion in biological ion channels. Due to the advantages of abundant pore channels, metal–organic frameworks (MOFs) have become competitive materials to control the nanofluidic transport. Herein, a facile in situ synthesis method is developed to prepare hybrid nanochannels constructed by 2D MOFs and porous anodic aluminum (PAA). The introduction of asymmetries in the chemical composition and surface charge properties gives the hybrid outstanding ion current rectification properties and excellent ion selectivity. A power density of 1.6 W m−2 is achieved by integrating it into a salinity‐gradient‐driven device. With advantages of facile fabrication method and high ion selectivity, the prepared 2D MOFs/PAA hybrid membrane offers a promising candidate for power conversion and water desalination.
A 2D metal–organic frameworks/porous anodic aluminum (MOFs/PAA) hybrid membrane is fabricated with a facile strategy via in situ growth of 2D MOFs on a nanoporous PAA membrane. The as‐prepared hybrid nanochannel presents obvious ionic rectification properties and excellent ion selectivity, which can be used for manipulating ion transport and efficient salinity‐gradient energy conversion.
PDF
