Search

Detection of nitro pollutants is an important topic in environmental protection. A total of 3 Cd (II) complexes (1–3) based on 3 soft organic isomers, n-(3,5-dicarboxylato benzyloxy) benzoic acid (n = 2, 3 or 4-H3DBB), and a linear N-donor ligand, 3-bis(imidazole-l-ylmethyl) benzene (3-bibz), have been synthesized hydrothermally. Structural diversity of Complexes 1–3 displays the architectural 2D or 3D change: Complex 1 exhibits a 2D network featuring tri-nuclear metal units, Complex 2 is a 3D framework based on similar tri-nuclear metal units, and Complex 3 shows a 3D network with binuclear units. Fluorescent sensing properties exhibited in all these complexes have been discovered to detect nitrobenzene (NB) selectively and sensitively. In particular, Complex 3 possesses high sensitivity for NB with the lowest detection limit of 1.15 × 10−10 M. The results of the theoretical calculation verified the fluorescence detection mechanism of NB by these Cd-based complexes. Therefore, these Cd-based complexes might be used as excellent luminescent sensors for NB. [ABSTRACT FROM AUTHOR]

Although the power conversion efficiency (PCE) of perovskite solar cells (PSCs) is 26.1%, their stability is still a roadblock for large‐scale commercialization. In the initial density‐functional theory research, it is shown that the most damaging type of defect that destroys device performance is undercoordinated Pb2+ on the surface of the perovskite thin film. An ultraviolet‐absorbent material, 2‐hydroxybenzophenone (HBP), is utilized to specifically passivate this type of defect. In theoretical studies, it is shown that it effectively binds to the undercoordinated Pb2+ via its –C═O group. It also passivates I−‐related defects by forming a hydrogen bond using its –OH group, resulting in decreased trap density and hence prolonged carrier lifetime. The HBP can absorb ultraviolet irradiation, leading to much‐reduced UV degradation; its hydrophobic benzene rings protect the perovskite from moisture permeation. As a result, the constructed device reaches a high PCE of 16.39% with superior stability. The bare device maintains 80.4% of its initial PCE after exposure to ambient air for 792 h. In comparison, the control device without HBP retains only 63.2% of its initial efficiency. Under UV irradiation (80 mW cm−2, 365 nm) for 13 h, the former retains 77.9% of its initial PCE while the control device lost 52% of its initial value. [ABSTRACT FROM AUTHOR]

Despite organic–inorganic hybrid perovskite devices having reached a photoelectric conversion efficiency (PCE) of 26.1%, their high cost and poor stability limit their industrial applications. Density functional theory (DFT) calculation reveals that the major defects originate from the lead vacancy (VPb) on the perovskite film surface. Therefore a two-dimensional material, phenethylammonium iodide (PEAI), was applied to passivate Pb2+ defects in the perovskite film. Theoretical studies show that uncoordinated Pb2+ can be effectively passivated, and in the meanwhile PEAI binds to iodine vacancies (VI) on the perovskite film surface through Lewis base–acid interactions, resulting in a significant decrease in trap density and a prolonged charge lifetime. The PEAI passivation leads to interfacial hole transfer, causing the band edge of the perovskite to move upward. We designed and constructed PSCs with carbon electrodes without hole transport layers, achieving the highest PCE of 17.27% and excellent stability. This strategy provides a useful reference for elevating the PCE and stability of perovskite cells. [ABSTRACT FROM AUTHOR]

Bimetallic methylidyne cluster cations such as [MAu(CH)] + (M = Pt, Ir, Os), featuring the combination of a less reactive (Au) and a more reactive (M) metal centers, exhibit very different reactivities with NH 3 . Density functional calculations confirm the direct C N coupling in all clusters, with the main products of PtAu/[CH 2 NH 2 ] + in the Pt system and [MAu(CNH 2 )] + (M = Ir, Os)/H 2 in the Ir and Os systems. Furthermore, for the first time, a feasible minor product reaction path leading to the direct formation of HCN has been located in both the Ir and Os systems. The great potential of regulating reaction pathways by designing bi- or multi-metallic catalysts is presented. [ABSTRACT FROM AUTHOR]

Abstract: Computational investigations on the reaction of IrAg+/CH4/NH3 have been carried out by the density functional approach. Calculations indicate that the reaction mainly consists of two essential processes. First, the C–H bond of methane could be effectively activated by the cation IrAg+, yielding the bimetallic cation carbene . Second, the resultant carbene species consecutively reacts with the ammonia to result in C–N bond coupling. [ABSTRACT FROM AUTHOR]

Abstract: A detailed investigation of the reaction mechanism underlying the small metal cluster IrAu+ mediated C–N coupling of methane and ammonia has been performed by the density functional theory. At first, both high-spin and low-spin potential energy surfaces are characterized in activation of methane by IrAu+ in detail. Our calculations indicate that the step reaction proceeds on the low-spin potential energy surface although it may involve crossing of potential energy surfaces. The C–H bond of methane could be effectively activated by the cation IrAu+, yielding the bimetallic cation carbene . Second, the reaction of the product and ammonia may result in C–N bond coupling, though loss of in methylene is the most favorable among the three paths dynamically. [Copyright &y& Elsevier]