A comparative study on the bond features in CO, CS, and PbS

Covalent and noncovalent interactions dominate most compounds in the condensed phase and gas phase. For a classical diatomic molecule CO, it is usually regarded as a triple-bond system with one dative bond. In this work, the photoelectron velocity-map imaging spectra of the CS and PbS anions were first measured. The two interactions have been intuitively understood by a comparative investigation of electrostatic potential (ESP) and bond features in CO, CS, and PbS. It is suggested that both electrostatic and dative covalent interactions compete in CO molecules, while dative covalent interaction prevails in CS molecules and electrostatic interaction dominates in PbS molecules. As a consequence, CO has a very small dipole moment (similar to 0.1 D) compared to the large dipole moment in CS (>1.8 D) and PbS (>4 D). It is indicated that the electron affinity value increases with the increasing dipole moment in the order of CO < CS < PbS. In addition, intriguing ESP with negative bond-ends and positive bond-cylindrical-surface in CO is also revealed by comparing with that in CS and PbS. In the latter, the two molecules present opposite ESP maps. Molecular orbital analyses indicate surprising participation of Pb 5d orbitals in the Pb-S chemical bonding although Pb belongs to main-group elements. Further bond analyses using electron localization function, natural resonance theory, and bond order methods suggest that covalence is dominant in CS and ionicity is a major component in PbS, but somewhere in between for CO molecules. By a comparative study in this work, the CS molecule is also revealed as a promising ligand molecule for the transition-metal coordination chemical synthesis. Published by AIP Publishing

A simple route to preparing γ-Fe2O3/RGO composite electrode materials for lithium ion batteries

A simple approach to synthesizing γ-FeO nanoparticles encapsulated by reduced graphene oxide (RGO) sheets is demonstrated for the first time. It was found that iron metal can substantially reduce few-layer graphene oxide (GO) to form reduced graphene oxide (RGO) in GO aqueous suspension under ambient conditions, and in the meantime be oxidized to form γ-FeO nanoparticles dispersed on the surface of RGO sheets. The γ-FeO/RGO composite delivered both stable cycling performance and good rate capability when used as an anode in a lithium-ion battery cell. This novel experimental method for synthesizing γ-FeO/RGO composite materials is cost-effective, eco-friendly and suitable for synthesizing other metal oxide/RGO composite materials

Assembly of large-area reduced graphene oxide films for the construction of Z-scheme over single-crystal porous Bi5O7I nanosheets

In this work, we have firstly achieved the construction of bismuth oxyiodide (BiOI)/reduced graphene oxide (rGO)/ZnO Z-scheme photoelectrochemical (PEC)system without backward reactions through loading large-area ZnO quantum dots (QDs)/rGO films on BiOI nanosheets. Single-crystal porous BiOI nanosheets with numerous oxygen vacancies (OVs)were firstly fabricated through the calcination of BiOI in reductive glycols. The single-crystal facilitates charge transport, nanoporous structure promotes light absorption and OVs improves charge separation efficiency. As a result, single-crystal porous BiOI nanosheets with OVs exhibited higher PEC performance than other morphologies reported before. Moreover, The PEC activity of BiOI can be further enhanced through loading large-area ZnO QDs/rGO films to construct a pure Z-scheme charge transfer system, which not only achieves efficient separation of electron-hole pairs but also retains its excellent redox ability. To the best of our knowledge, the photocurrent density of BiOI/rGO/ZnO heterostructures is the highest among BiOI-based samples. For comparison, an opposite Z-scheme model has also been built up by replacing BiOI with WO, in which the photocurrent density decreased conversely. Therefore, it can be known that a pure Z-scheme system without backward reactions can be successfully prepared through loading ZnO QDs/rGO films on photoelectrodes

Two-Step High-Temperature Calcination of BiVO₄/TiO₂/Ti₃C₂ Nanocomposites as a High-Efficiency Photoelectrochemical Platform for Enhanced Photovoltaic Performance

Environmental issues, such as increasingly polluted water resources and energy shortages, have led to the need for new strategies to promote sustainable progress and enhance human well-being. Photocatalysis is widely recognized as a promising technology for environmental sustainability. MXene is a two-dimensional nanotransition metal material, which has attracted extensive attention in the field of photocatalysis. In MXenes, titanium carbide (Ti3C2) has been extensively studied for its application in photocatalysis due to its unique nanolayered structure. The Ti site on the surface of Ti3C2 has a stronger redox activity than traditional C materials, and Ti3C2 has high electrical conductivity. The focus of this study is to obtain the Ti3C2/TiO2 composite by in situ calcination of Ti3C2 and then combine Mo,W:BVO with TiO2 to form feasible heterojunctions. The excellent electrical conductivity of Ti3C2 promotes the transfer of electrons and holes between Mo,W:BVO and TiO2, thus establishing a cascade that minimizes charge carrier recombination and exhibits strong photocatalytic activity. Through a series of photocatalytic tests, the optimum calcination temperature and time of Ti3C2 (550 °C, 2.5 h) and the doping amount of Ti3C2 (2 mg/mL) were determined. Under these conditions, a high current density of 3.8 mA cm–2 was obtained, showing excellent photostability. This study confirmed the strong photocatalytic activity of the synthesized nanoscale composites Mo,W:BVO/TiO2/Ti3C2, providing valuable insights for the design of efficient and sustainable photocatalysts in the future

BiAg Alloy Nanospheres: A New Photocatalyst for H₂ Evolution from Water Splitting

We demonstrate for the first time that Bi and BiAg alloy nanospheres, fabricated with a facile hydrothermal method, display evident photocatalytic H₂ production activities. Element Bi can serve as an active photocatalyst for both water splitting and photoelectrochemical applications. More interestingly, these activities of Bi can be greatly enhanced by introducing Ag to form BiAg alloy nanoparticles, which may be ascribed to the improved charge separation and enlarged carrier concentration. The constituent of the BiAg alloy can be rationally tuned by varying the amount of Ag nanowires, and it is found that Bi_0.7Ag_0.3 exhibits the highest photoelectrochemical property

A standard for hilar and intrapulmonary lymph node dissection and pathological examination in early non-small cell lung cancer

Background: There is considerable variation in the staging of lymph nodes (LNs) as part of tumor, node, metastasis (TNM) staging of non-small cell lung cancer (NSCLC). A new dissection and pathological examination standard for hilar and intrapulmonary LNs needs to be established for patients with early-stage T1-3N0M0 NSCLC. Methods: This study involved 3,002 patients with T1-3N0M0 NSCLC who underwent radical lobectomy or total pneumonectomy in the thoracic departments of 11 Chinese institutions between January 1999 and October 2013. The Cox model was applied for univariate and multivariate analyses in the examination of station 10, 11 LN and station 12, 13, 14 LN. A hilar and intrapulmonary standard (HI standard) was then established based on univariate and multiple-factor analyses conducted using the Cox model. Results: Among the 3,002 patients enrolled in the study, 2,609 underwent at least one examination of station 10, 11 LN (A1), while 393 did not undergo examination of station 10, 11 LN (A0). The A0 and A1 groups had 5-year survival rates of 76% and 80%, respectively (P=0.018). Further, 1,764 patients underwent at least one examination of station 12, 13, 14 LN (B1), while 1,238 patients did not (B0). The B0 and B1 groups had 5-year survival rates of 77% and 82%, respectively (P=0.008). In total, 1,269 patients attained the HI standard (C1), and 1,733 did not (C0). The C0 and C1 groups had 5-year survival rates of 77% and 83%, respectively (P<0.001). Conclusions: The HI standard can improve both the prognosis and survival rates of patients with T1-3N0M0 NSCLC. This will provide important guidance for pulmonary LN dissection and pathological examination in NSCLC cases