Reversibly Modulating the Selectivity of Carbon Dioxide Reduction via Ligand-Driven Spin Crossover.

Selectivity is an essential aspect in catalysis. At present, the improvement of the selectivity for complex reactions with multiple pathways/products, for example the carbon dioxide reduction reaction (CORR), can usually be achieved for only one pathway/product. It is still a challenge to reversibly modulate the selectivity between two reaction pathways or products of the CORR by one catalyst.

Vertical Dipole Dominates Charge Carrier Lifetime in Monolayer Janus MoSSe.

Two-dimensional semiconductor materials with vertical dipoles are promising photocatalysts as vertical dipoles not only promote the electron-hole separation but also enhance the carrier redox ability. However, the influence of vertical dipoles on carrier recombination in such materials, especially the competing relationship between vertical dipoles and band gaps, is not yet clear. Herein, first-principles calculations and nonadiabatic molecular dynamics simulations were combined to clarify the influence of band gap and vertical dipole on the carrier lifetime in Janus MoSSe monolayer.

Electron-Induced Synthesis of Dimethyl Ether in the Liquid-Vapor Interface of Methanol.

Ether synthesis from alcohol is known to be acid-catalyzed. Such a process could happen in the acidified liquid of alcohol, but hitherto lacking the experimental evidence. Here we demonstrate that dimethyl ether is spontaneously synthesized in the liquid-vapor interface of pure methanol after ionizing radiation with electrons.

High-performance photocatalytic nonoxidative conversion of methane to ethane and hydrogen by heteroatoms-engineered TiO.

Nonoxidative coupling of methane (NOCM) is a highly important process to simultaneously produce multicarbons and hydrogen. Although oxide-based photocatalysis opens opportunities for NOCM at mild condition, it suffers from unsatisfying selectivity and durability, due to overoxidation of CH with lattice oxygen. Here, we propose a heteroatom engineering strategy for highly active, selective and durable photocatalytic NOCM.

Promoting Water Activation by Photogenerated Holes in Monolayer CN.

In photocatalytic reactions, the activation of HO is very important for achieving high energy conversion efficiency. However, its activation mechanism under photoirradiation is still not fully understood. Here, on the basis of first-principles calculations, the role of photogenerated holes on the activation of HO is investigated in a typical photocatalytic material CN.

Designing Direct Z-Scheme Heterojunctions Enabled by Edge-Modified Phosphorene Nanoribbons for Photocatalytic Overall Water Splitting.

Direct Z-scheme photocatalyst possess promising potential to utilize solar radiation for photocatalytic overall water splitting; however, the design and characterization remain challenging. Here, we construct and verify a direct Z-scheme heterojunction using edge-modified phosphorene-nanoribbons (X-PNRs, where X = OH and OCN) with first-principles ground-state and excited-state density functional theory (DFT) calculations. The ground-state calculations provide fundamental properties such as geometric structure and band alignment.

A rationally designed two-dimensional MoSe/TiCO heterojunction for photocatalytic overall water splitting: simultaneously suppressing electron-hole recombination and photocorrosion.

Electron-hole recombination and photocorrosion are two challenges that seriously limit the application of two-dimensional (2D) transition metal dichalcogenides (TMDs) for photocatalytic water splitting. In this work, we propose a 2D van der Waals MoSe/TiCO heterojunction that features promising resistance to both electron-hole recombination and photocorrosion existing in TMDs. By means of first-principles calculations, the MoSe/TiCO heterojunction is demonstrated to be a direct Z-scheme photocatalyst for overall water splitting with MoSe and TiCO serving as photocatalysts for hydrogen and oxygen evolution reactions, respectively, which is beneficial to electron-hole separation.

2D Heterostructured Nanofluidic Channels for Enhanced Desalination Performance of Graphene Oxide Membranes.

The two-dimensional (2D) lamellar membrane assembly technique shows substantial potential for sustainable desalination applications. However, the relatively wide and size-variable channels of 2D membranes in aqueous solution result in inferior salt rejections. Here we show the establishment of nanofluidic heterostructured channels in graphene oxide (GO) membranes by adding g-CN sheets into GO interlamination.

Identifying the Molecular Orientation and Clusters in the Liquid-Vapor Interface of 1-Propanol by Time-Delayed Mass Spectrometry.

Structural inhomogeneity of the liquid-vapor interface, such as the spatial orientation of molecular specific groups and the non-uniform distribution of hydrogen-bonded (HB) clusters, is crucial for understanding the physicochemical processes therein. Although the molecular orientation at the outermost layer was authenticated, to date, direct experimental evidence of the existence of different-sized HB clusters, as a long-standing theoretical argument, is still lacking. Here we report time-delayed electron-impact tandem mass spectrometry, and its powerful ability to identify the local structures of the liquid-vapor interface of 1-propanol is demonstrated not only by mapping the molecular orientations both in the outermost layer and in the subsurface but also by validating the existence of the HB molecular dimers in the subsurface by detecting their protonated ions.

Endowing g-C N Membranes with Superior Permeability and Stability by Using Acid Spacers.

g-C N membranes were modulated by intercalating molecules with SO H and benzene moieties between layers. The intercalation molecules break up the tightly stacking structure of g-C N laminates successfully and accordingly the modified g-C N membranes give rise to two orders magnitude higher water permeances without sacrificing the separation efficiency. The sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO)/g-C N with a thickness of 350 nm presents an exceptionally high water permeance of 8867 L h  m  bar and 100 % rejection towards methyl blue, while the original g-C N membrane with a thickness of 226 nm only exhibits a permeance of 60 L h  m  bar .

Construction of direct Z-Scheme photocatalysts for overall water splitting using two-dimensional van der waals heterojunctions of metal dichalcogenides.

The direct Z-scheme system constructed by two-dimensional (2D) materials is an efficient route for hydrogen production from photocatalytic water splitting. In the present work, the 2D van der Waals (vdW) heterojunctions of MoSe /SnS , MoSe /SnSe , MoSe /CrS , MoTe /SnS , MoTe /SnSe , and MoTe /CrS are proposed to be promising candidates for direct Z-scheme photocatalysts and verified by first principles calculations. Perpendicular electric field is induced in these 2D vdW heterojunctions, which enhances the efficiency of solar energy utilization.

Material Design for Photocatalytic Water Splitting from a Theoretical Perspective.

Currently, problems associated with energy and environment have become increasingly serious. Producing hydrogen, a clean and renewable resource, through photocatalytic water splitting using solar energy is a feasible and efficient route for resolving these problems, and great efforts have been devoted to improve the solar-to-hydrogen efficiency. Light harvesting and electron-hole separation are key in enhancing the efficiency of solar energy utilization, which stimulates the development of new photocatalytic materials.

Intrinsic Electric Fields in Two-dimensional Materials Boost the Solar-to-Hydrogen Efficiency for Photocatalytic Water Splitting.

Two-dimensional (2D) materials with the vertical intrinsic electric fields show great promise in inhibiting the recombination of photogenerated carriers and widening light absorption region for the photocatalytic applications. For the first time, we investigated the potential feasibility of the experimentally attainable 2D MX (M = Al, Ga, In; X = S, Se, Te) family featuring out-of-plane ferroelectricity used in photocatalytic water splitting. By using first-principles calculations, all the nine members of 2D MX are verified to be available photocatalysts for overall water splitting.

On the shuttling mechanism of a chlorine atom in a chloroaluminum phthalocyanine based molecular switch.

An intermediate shuttling structure of a chloroaluminum phthalocyanine(ClAlPc)-based molecular switch is transiently created and analyzed by combined scanning tunneling microcopy/spectroscopy and density-functional theory calculations, which suggests that the Cl atom is squeezed into the space between the central Al atom and the inner N-containing ring in ClAlPc.

Mono-Mercury Doping of Au25 and the HOMO/LUMO Energies Evaluation Employing Differential Pulse Voltammetry.

Controlling the bimetal nanoparticle with atomic monodispersity is still challenging. Herein, a monodisperse bimetal nanoparticle is synthesized in 25% yield (on gold atom basis) by an unusual replacement method. The formula of the nanoparticle is determined to be Au24Hg1(PET)18 (PET: phenylethanethiolate) by high-resolution ESI-MS spectrometry in conjunction with multiple analyses including X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA).

Different aggregation dynamics of benzene-water mixtures.

All-atom molecular dynamics simulations for benzene-water mixtures are performed, aiming to explore the relationship between the microscopic structures and the thermodynamic properties, in particular, the transformation dynamics from the mutually soluble state to the phase-separated state. We find that the molecular aggregation of benzene in the water-rich mixture is distinctly different from that of water in the benzene-rich mixture. This aggregation difference is attributed to the different intermolecular interactions: the clustering of benzene molecules in the water-rich mixture is primarily driven by weak short-distance π-π interactions; while the formation of water clusters in the benzene-rich solution is triggered by long-range dipole-dipole electrostatic interactions.

A Comparative Study for Molecular Dynamics Simulations of Liquid Benzene.

The classical equilibrium and nonequilibrium molecular dynamics simulations for liquid benzene, the prototypical aromatic π-π interaction system, are performed using a variety of molecular force fields, OPT-FF, AMBER 03, general AMBER force field (GAFF), OPLS-AA, OPLS-CS, CHARMM27, GROMOS 53A5, and GROMOS 53A6. The simulated results of the molecular structure and thermodynamic properties of liquid benzene are compared with the experimental data available in the literature, accounting for the superiority of each force field in the descriptions of the π-π interaction system. The OPLS-AA force field is recommended to be the best one, which reproduces quite well the properties examined in this work, while the others fail in predicting either the local structure or the thermodynamic properties.

Molecular dynamics study of solvation differences between cis- and transplatin molecules in water.

The classical molecular dynamics (MD) simulations for the solvation properties of cis- and transplatins in water are performed with the Lennard-Jones plus Coulomb electrostatic potential parameters that are optimized with ab initio potential energies of the water-platin systems. Two hydration shells are found both for cis- and transplatins. The first shell of water molecules is closer to transplatin than cisplatin.