Designing Double Perovskites with Organic Dications for Enhancing Stability and Photoelectrical Performance.

Recently, the research on developing lead-free double-B-cation halide perovskites has attracted attention. However, CsInBiCl, the most promising one, was shown to be thermodynamically unstable. To improve the stability, organic dication DiMA (i.

Role of HO Adsorption in CO Oxidation over Cerium-Oxide Cluster Anions (CeO)O ( = 1-4).

Water (HO) is ubiquitous in the environment and inevitably participates in many surface reactions, including CO oxidation. Acquiring a fundamental understanding of the roles of HO molecules in CO oxidation poses a challenging but pivotal task in real-life catalysis. Herein, benefiting from state-of-the-art mass-spectrometric experiments and quantum chemical calculations, we identified that the dissociation of a HO molecule on each of the cerium oxide cluster anions (CeO)O ( = 1-4) at room temperature can create a new atomic oxygen radical (O) that then oxidizes a CO molecule.

Revisiting the thermal decomposition mechanism of MAPbI.

The thermal stability of MAPbI poses a challenge for the industry. To overcome this limitation, a thorough investigation of MAPbI is necessary. In this work, thermal gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy were conducted to identify the thermal decomposition products of MAPbI, which were found to be CHI, NH, and PbI.

Effect of External Electric Field on Nitrogen Activation on a Trimetal Cluster.

Efficient nitrogen (N) fixation and activation under mild conditions are crucial for modern society. External electric fields (F) can significantly affect N activation. In this work, the effect of F on N activation by Nb clusters supported in a sumanene bowl was studied by density functional theory calculations.

Catalysts with Trimetallic Sites on Graphene-like CN for Electrocatalytic Nitrogen Reduction Reaction: A Theoretical Investigation.

Electrocatalytic nitrogen reduction reaction (NRR) is a green and highly efficient way to replace the industrial Haber-Bosch process. Herein, clusters consisting of three transition metal atoms loaded on CN as NRR electrocatalysts are investigated using density functional theory (DFT). Meanwhile, Ca was introduced as a promoter and the role of Ca in NRR was investigated.

Exploring the stability and aromaticity of rare earth doped tin cluster MSn (M = Sc, Y, La).

Rare earth elements have high chemical reactivity, and doping them into semiconductor clusters can induce novel physicochemical properties. The study of the physicochemical mechanisms of interactions between rare earth and tin atoms will enhance our understanding of rare earth functional materials from a microscopic perspective. Hence, the structure, electronic characteristics, stability, and aromaticity of endohedral cages MSn (M = Sc, Y, La) have been investigated using a combination of the hybrid PBE0 functional, stochastic kicking, and artificial bee colony global search technology.

Heteronuclear Trimetallic MFe and M Fe (M=V, Nb, and Ta) Clusters for Dinitrogen Activation.

Catalysts with heteronuclear metal active sites may have high performance in the nitrogen reduction reaction (NRR), and the in-depth understanding of the reaction mechanisms is crucial for the design of related catalysts. In this work, the dissociative adsorption of N on heteronuclear trimetallic MFe and M Fe (M=V, Nb, and Ta) clusters was studied with density functional theory calculations. For each cluster, two reaction paths were studied with N initially on M and Fe atoms, respectively.

Trimetallic clusters in the sumanene bowl for dinitrogen activation.

It is of great importance to find catalysts for the nitrogen reduction reaction (NRR) with high stability and reactivity. A series of M clusters (M = Ti, Zr, V, and Nb) supported on sumanene (CH) were designed as potential catalysts for the NRR by taking advantage of the high reactivity of trimetallic clusters and the unique geometric and electronic properties of sumanene, a bowl-like organic molecule. Detailed mechanisms of NN bond cleavage on CH-M were investigated by DFT calculations and compared with those on bare M clusters.

Comparison of Nitrogen Activation on Trinuclear Niobium and Tungsten Sulfide Clusters Nb S and W S (n=0-3): A DFT Study.

The front cover artwork is provided by Prof. Xun-Lei Ding's group at North China Electric Power University (NCEPU). The image shows the cleavage of the triple bond of a dinitrogen molecule on trinuclear metal clusters with sulfide ligands, which is the critical step in nitrogen reduction reactions (NRR).

Small practical cluster models for perovskites based on the similarity criterion of central location environment and their applications.

Developing universal theoretical models for perovskites (often denoted as ABX) can contribute to the rational design of novel perovskite photovoltaic materials. However, few models can be successfully applied to study the intrinsic electronic structure due to the poor accuracy and unaffordable computational cost. Herein, we report the innovative construction of small practical cluster models through the similarity criterion of the central location environment, which retains only the central A-site as the original cation while the others are substituted by Cs to keep the clusters electrically neutral.

Comparison of Nitrogen Activation on Trinuclear Niobium and Tungsten Sulfide Clusters Nb S and W S (n=0-3): A DFT Study.

The reaction of N with trinuclear niobium and tungsten sulfide clusters Nb S and W S (n=0-3) was systematically studied by density functional theory calculations with TPSS functional and Def2-TZVP basis sets. Dissociations of N-N bonds on these clusters are all thermodynamically allowed but with different reactivity in kinetics. The reactivity of Nb S is generally higher than that of W S .

A descriptor for the structural stability of organic-inorganic hybrid perovskites based on binding mechanism in electronic structure.

The poor stability of organic-inorganic hybrid perovskites hinders its commercial application, which motivates a need for greater theoretical insight into its binding mechanism. To date, the binding mode of organic cation and anion inside organic-inorganic hybrid perovskites is still unclear and even contradictory. Therefore, in this work based on density functional theory (DFT), the binding mechanism between organic cation and anion was systematically investigated through electronic structure analysis including an examination of the electronic localization function (ELF), electron density difference (EDD), reduced density gradient (RDG), and energy decomposition analysis (EDA).

Exploring the Effects of Ionic Defects on the Stability of CsPbI with a Deep Learning Potential.

Inorganic metal halide perovskites, such as CsPbI , have recently drawn extensive attention due to their excellent optical properties and high photoelectric efficiencies. However, the structural instability originating from inherent ionic defects leads to a sharp drop in the photoelectric efficiency, which significantly limits their applications in solar cells. The instability induced by ionic defects remains unresolved due to its complicated reaction process.

High throughput screening of promising lead-free inorganic halide double perovskites first-principles calculations.

Perovskite solar cells (PSCs) have been intensively investigated and made great progress due to their high photoelectric conversion efficiency and low production cost. However, poor stability and the toxicity of Pb limit their commercial applications. It is particularly important to search for new non-toxic, high-stability perovskite materials.

Mechanochemical bromination of unburned carbon in fly ash and its mercury removal mechanism: DFT study.

The mechanochemical (MC) brominated fly ash is a cost-effective mercury removal adsorbent, in which unburned carbon (UBC) plays an important role. The MC bromination mechanism of UBC and its mercury removal mechanism were completely studied through the density functional theory (DFT) method. Various defects on zigzag and armchair edge models were constructed at the micro-scale to simulate the MC effect on UBC at the macro-scale.

Facile N≡N Bond Cleavage by Anionic Trimetallic Clusters V Ta C (x=0-3): A DFT Study.

Activation of N on anionic trimetallic V Ta C (x=0-3) clusters was theoretically studied employing density functional theory. For all studied clusters, initial adsorption of N (end-on) on one of the metal atoms (denoted as Site 1) is transferred to an of end-on: side-on: side-on coordination on three metal atoms, prior to N dissociation. The whole reaction is exothermic and has no global energy barriers, indicating that the dissociation of N is facile under mild conditions.

Non-Dissociative Activation of Chemisorbed Dinitrogen on One or Two Vanadium Atoms Supported by a Mo S Cluster.

Adsorption of N on Mo S _V clusters (x=0, 1, 2; q=0, ±1) were systematically studied by density functional theory calculations with dispersion corrections. It was found that the N can be chemisorbed and undergo non-dissociative activation on single or double metal atoms. The adsorption and activation are influenced by metal types (V or Mo), N coordination modes and charge states of the clusters.

A new perspective for evaluating the photoelectric performance of organic-inorganic hybrid perovskites based on the DFT calculations of excited states.

The high efficiency of organic-inorganic hybrid perovskites has attracted the attention of many scholars all over the world, the chemical formula of which is ABX3, where A is an organic cation, B is a metal cation, and X is a halogen ion. In addition, the micro-mechanism behind the efficient photoelectric conversion needs more in-depth exploration. Therefore, in this work, based on time-dependent density functional theory (TD-DFT), the electron transfer mechanism from the ground state to the first singlet excited state was systematically investigated by electron and hole analysis and an inter-fragment charge transfer amount method (IFCT).

Non-stoichiometric molybdenum sulfide clusters and their reactions with the hydrogen molecule.

Structures of non-stoichiometric MoxSy clusters (x = 2-4; y = 2-10) were studied by density functional calculations with global optimization. Besides 1T phase like structures, a novel regular grid structure in which Mo atoms are well separated by S atoms was found, which might be used as a building-block to construct a new type of two-dimensional molybdenum sulfide monolayer. The hydrogen molecule prefers to be adsorbed onto Mo atoms rather than S atoms, and Mo atoms with less S coordination have a higher ability to adsorb H2.

Screening the activity of single-atom catalysts for the catalytic oxidation of sulfur dioxide with a kinetic activity model.

An accurate prediction model of catalytic activity is crucial for both structure design and activity regulation of catalysts. Here, a kinetic activity model is developed to study the activity of single-atom catalysts (SACs) in catalytic oxidation of sulfur dioxide. Using the adsorption energy of the oxygen atom as a descriptor, the catalytic activities of 132 SACs were explored.

C/C Exchange in Activation/Coupling Reaction of Acetylene and Methane Mediated by Os: A Comparison with Ir, Pt, and Au.

The activation and coupling reactions of methane and acetylene mediated by M (M = Os, Ir, Pt, and Au) have been comparatively studied at room temperature by the techniques of mass spectrometry in conjunction with theoretical calculations. Studies have shown that Os and Ir can mediate the activation/coupling reaction of CH and CH, while Pt and Au cannot, which could be explained by the number of empty valence orbitals in the metal atom. In addition, there are different competition channels for the reaction mediated by Os and Ir: an expected dehydrogenation and an unexpected C/C exchange.

Methane activation by heteronuclear diatomic AuRh cation: comparison with homonuclear Au and Rh.

The ability to activate methane differs appreciably for different transition metals, and it is attractive to find the most suitable metal for the direct conversion of methane to value-added chemicals. Herein, we performed a comparative study on the reactions of CH with Au, AuRh and Rh cations by mass-spectrometry based experiments and DFT-based theoretical analysis. Different reactivity has been found for these cations: Au has the lowest reactivity, and it can activate methane but only produce H-Au-CH without H release; Rh has the highest reactivity, and it can produce both carbene-type Rh-CH and carbyne-type H-Rh-CH with H release; AuRh also has high reactivity to produce only AuRh-CH with H, avoiding the excessive dehydrogenation of CH.

The effect of coordination environment on the kinetic and thermodynamic stability of single-atom iron catalysts.

The stability of a single-atom catalyst is directly related to its preparation and applications, especially for high-loading single-atom catalysts. Here, the effect of a coordination environment induced by nitrogen (N) atoms coordinated with iron on the kinetic and thermodynamic stabilities of single-atom iron catalysts supported with carbon-based substrates (Fe/CS) was investigated by density functional theory (DFT) calculations. Five Fe/CS with different numbers of N atoms were modelled.

Theoretical study on the stability of the complexes A···BX [A = CHNH, NHCHNH, NHCHOH; B = Sn, Pb; X = F, Cl, Br, I].

The interaction of corresponding molecular building blocks of the complexes A···BX would provide valuable information to quickly estimate the properties of the solar cell. In this work, the H···X hydrogen bond between the organic cations A (CHNH, NHCHNH, NHCHOH) and the inorganic anions BX (B = Sn, Pb, X = F, Cl, Br, I) were studied by theoretical calculation at the B3LYP-D3/ma-def2-TZVP level to investigate the stability of the complexes A···BX. The strength of H···X hydrogen bond is enhanced in the order of NHCHNH < CHNH < NHCHOH, Sn < Pb, and weakened in the order of F > Cl > Br > I, indicating that the complexes A···BX enhances with the increase of electron donating ability of B and the decrease of electron donating ability of X, and application of the substituent A = NHCHOH may be effective to enhance the stability of perovskite and replace the toxic metal Pb by Sn.