Polycyclic aromatic hydrocarbons with hexagons/pentagons or hexagons/heptagons have been intensively investigated in recent years, but those with simultaneous presence of hexagons, pentagons and ...heptagons remain rare. In this paper, we report dicycloheptaijkl,uvwxrubicene (DHR), a non‐benzenoid isomer of dibenzobc,klcoronene with two pentagons and two heptagons. We developed an efficient and scalable synthetic method for DHR by using Scholl reaction and dehydrogenation. Crystal structure of DHR shows that the benzenoid rings, two pentagons and two heptagons are coplanar. The bond lengths analysis and the ICSS(1)zz and LOL‐π calculations indicate that the incorporation of two formal azulene moieties has an effect on the conjugated structure. The π‐electrons of benzenoid and pentagon rings are more delocalized. Cyclic voltammetry studies indicate that DHR shows multiple oxidation and reduction potentials. Interestingly, DHR exhibits unusual S0 to S2 absorption and abnormal anti‐Kasha S2 to S0 emission. Moreover, crystals of DHR exhibit semiconducting behaviour with hole mobility up to 0.082 cm2 V−1 s−1.
The electrocatalytic nitrogen reduction reaction (NRR) on metal‐free catalysts is an attractive alternative to the industrial Haber–Bosch process. However, the state‐of‐the‐art metal‐free ...electrocatalysts still suffer from low Faraday efficiencies and low ammonia yields. Herein, we present a molecular design strategy to develop a defective boron carbon nitride (BCN) catalyst with the abundant unsaturated B and N atoms as Lewis acid and base sites, which upgrades the catalyst from a single “Lewis acid catalysis” to “frustrated Lewis pairs (FLPs) catalysis.” 14N2/15N2 exchange experiments and density functional theory (DFT) calculations reveal that FLPs can adsorb an N2 molecule to form a six‐membered ring intermediate, which enables the cleavage of N2 via a pull–pull effect, thereby significantly reducing the energy barrier to −0.28 eV. Impressively, BCN achieves a high Faraday efficiency of 18.9 %, an ammonia yield of 20.9 μg h−1 mg−1cat., and long‐term durability.
Defect‐controlled boron carbon nitride (BCN) is synthesized with electron‐deficient B atoms and electron‐rich N atoms in defects, forming frustrated Lewis pairs (FLP) to promote the electrocatalytic N2 reduction to ammonia.
Polycyclic aromatic hydrocarbons with hexagons/pentagons or hexagons/heptagons have been intensively investigated in recent years, but those with simultaneous presence of hexagons, pentagons and ...heptagons remain rare. In this paper, we report dicycloheptaijkl,uvwxrubicene (DHR), a non‐benzenoid isomer of dibenzobc,klcoronene with two pentagons and two heptagons. We developed an efficient and scalable synthetic method for DHR by using Scholl reaction and dehydrogenation. Crystal structure of DHR shows that the benzenoid rings, two pentagons and two heptagons are coplanar. The bond lengths analysis and the ICSS(1)zz and LOL‐π calculations indicate that the incorporation of two formal azulene moieties has an effect on the conjugated structure. The π‐electrons of benzenoid and pentagon rings are more delocalized. Cyclic voltammetry studies indicate that DHR shows multiple oxidation and reduction potentials. Interestingly, DHR exhibits unusual S0 to S2 absorption and abnormal anti‐Kasha S2 to S0 emission. Moreover, crystals of DHR exhibit semiconducting behaviour with hole mobility up to 0.082 cm2 V−1 s−1.
Neues Nanographen: Die Synthese eines stabilen und planaren Nanographens mit zwei Pentagons und zwei Heptagons in Gramm‐Mengen wird vorgestellt. Das Material eignet sich als p‐Halbleiter in organischen Feldeffekttransistoren.
Polycyclic aromatic hydrocarbons with hexagons/pentagons or hexagons/heptagons have been intensively investigated in recent years, but those with simultaneous presence of hexagons, pentagons and ...heptagons remain rare. In this paper, we report dicycloheptaijkl,uvwxrubicene (DHR), a non‐benzenoid isomer of dibenzobc,klcoronene with two pentagons and two heptagons. We developed an efficient and scalable synthetic method for DHR by using Scholl reaction and dehydrogenation. Crystal structure of DHR shows that the benzenoid rings, two pentagons and two heptagons are coplanar. The bond lengths analysis and the ICSS(1)zz and LOL‐π calculations indicate that the incorporation of two formal azulene moieties has an effect on the conjugated structure. The π‐electrons of benzenoid and pentagon rings are more delocalized. Cyclic voltammetry studies indicate that DHR shows multiple oxidation and reduction potentials. Interestingly, DHR exhibits unusual S0 to S2 absorption and abnormal anti‐Kasha S2 to S0 emission. Moreover, crystals of DHR exhibit semiconducting behaviour with hole mobility up to 0.082 cm2 V−1 s−1.
Gamma-ray (γ-ray) irradiation effects on HfO2-based MOS capacitors have been studied. The capacitance-voltage (C-V) characteristic was measured at room temperature (300 K) to study the change of ...electrical properties in capacitors before and after irradiation with different doses. The shifts of midgap and flatband voltage and the decrease of accumulation capacitance shown that defects in the oxide and interface traps were indeed created during the gamma irradiation. Deep level transient spectroscopy (DLTS) was used to characterize the interfacial states introduced by irradiation. The activation energies, capture cross-sections and interface state densities were EC-0.1697 eV, EC-0.1929 eV; 7.371 × 10−16 cm2, 1.158 × 10−14 cm2; 1.814 × 1013 eV−1 cm2, 5.042 × 1013 eV−1 cm2 for the 1 Mrad(Si) and 5 Mrad(Si) samples, respectively. The peak shifted toward lower temperature when increasing pulse voltages (VP) in measuring DLTS spectra with fixed reverse voltage (VR). It indicated that interface defects have been formed during irradiation. With the increasing of irradiation dose, both of the capture cross section (σn) and the interface state density (Dit) increased. These results provide the basis to the researches and applications for the HfO2-based devices in the field of high-κ materials, irradiation effect, devices in radiation working environment.
Display omitted C-V curves and DLTS spectra for HfO2 capacitors before and after γ-ray irradiation.
•Gamma-ray (γ-ray) irradiation effects on the high-k dielectric HfO2-based MOS capacitors have been studied by CV and DLTS.•The γ-ray irradiation could introduce defects in oxide and interface state defects to the silicon/HfO2 interface•A comparison of the results illustrated that the flat band voltage (Vfb) shifted to negative direction and the value of the capacitance at accumulation region increased with the increase of irradiation dose. On the other hand, irradiation dose, the Dit and the capture cross section became higher.
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