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 M 2 X 3 (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 M 2 X 3 are verified to be available photocatalysts for overall water splitting. The predicted solar-to-hydrogen efficiency of Al 2 Te 3 , Ga 2 Se 3 , Ga 2 Te 3 , In 2 S 3 , In 2 Se 3 , and In 2 Te 3 are larger than 10%. Excitingly, In 2 Te 3 is manifested to be an infrared-light driven photocatalyst, and its solar-to-hydrogen efficiency limit using the full solar spectrum even reaches up to 32.1%, which breaks the conventional theoretical efficiency limit.

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). X-ray single-crystal diffraction reveals that the structure of Au24Hg1(PET)18 remains the structural framework of Au25(PET)18 with one of the outer-shell gold atoms replaced by one Hg atom, which is further supported by theoretical calculations and experimental results as well. Importantly, differential pulse voltammetry (DPV) is first employed to estimate the highest occupied molecular orbit (HOMO) and the lowest unoccupied molecular orbit (LUMO) energies of Au24Hg1(PET)18 based on previous calculations.

involved in water splitting and exploring photocatalysts for water splitting are of extraordinarily interest for both fundamental research and practical industrial applications. [4][5][6][7] As known, there are three major processes in photocatalytic water splitting, including light harvest, separation, and migration of photogenerated electrons and holes, and hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on the surface of photocatalysts. The primary requirement to realize photocatalytic water splitting is that the redox potentials of water must lie between the bandgaps of photocatalysts, i.e., the conduction band minimum (CBM) should be higher than the reduction potential of H + /H 2 , and the valance band maximum (VBM) should be lower than the oxidation potential of H 2 O/O 2 simultaneously. Therefore, the bandgaps of photocatalysts should be larger than 1.23 eV, which is the minimum value of energy demanded to split water into hydrogen and oxygen. The photogenerated carriers in photocatalyst transfer into water molecules absorbed at the surface of photocatalysts to accomplish the HER and OER processes. As the electron-transfer process will inevitably lead to energy loss, and the kinetic overpotentials are needed to overcome the barriers of HER and OER, the bandgaps of photocatalysts are usually larger than 1.8 eV. [2] In addition, the performance of photocatalysts for water splitting still strongly depends on other factors, such as the sunlight adsorption, trapping, and recombination of the irradiation-excited electrons and holes, and surface reactivities of photocatalysts toward HER and OER. [8] Actually, these factors affect and interact with each other. The irradiation-excited electrons or holes should provide enough energy to drive HER and OER, which relies on the surface chemical reactivity of photocatalysts. A wide bandgap of photocatalyst guarantees this point, but a large value of bandgap indicates that photocatalyst cannot utilize long-wavelength photons in sunlight, limiting the solarto-hydrogen conversion efficiency. Noting that the solar spectrum includes a small fraction of ultraviolet (UV) light (<400 nm), comprising only ≈6.8% of the solar power, while the visible light (400-700 nm) accounts for about 38.9% of the solar power and around 54.3% of sunlight is located in the near-infrared (IR) range (760-3000 nm). Therefore, exploring photocatalytic materials with narrow bandgaps and suitable 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. Here, recent advances in material design for photocatalytic water spl...

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. Such distinct discrepancies for the above force fields are discussed within the scheme of the pairwise interaction construction of the standard force field, which will stimulate searching for a force field with generally good quality not only in terms of microstructure descriptions but also in the predictions of the thermodynamic properties of the liquids.

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 CH4 with lattice oxygen. Here, we propose a heteroatom engineering strategy for highly active, selective and durable photocatalytic NOCM. Demonstrated by commonly used TiO2 photocatalyst, construction of Pd–O4 in surface reduces contribution of O sites to valence band, overcoming the limitations. In contrast to state of the art, 94.3% selectivity is achieved for C2H6 production at 0.91 mmol g–1 h–1 along with stoichiometric H2 production, approaching the level of thermocatalysis at relatively mild condition. As a benchmark, apparent quantum efficiency reaches 3.05% at 350 nm. Further elemental doping can elevate durability over 24 h by stabilizing lattice oxygen. This work provides new insights for high-performance photocatalytic NOCM by atomic engineering.

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-C3N4 sheets into GO interlamination. Benefiting from the presence of stable and sub-nanometer wide (0.42 nm) GO/g-C3N4 channels, the GO/g-C3N4 membrane exhibits salt rejections of ∼90% with water permeances of above 30 L h–1 m–2 bar–1, while the pure GO membrane only has salt rejections of below 30% accompanied by water permeances of below 4 L h–1 m–2 bar–1. Combining experimental and theoretical investigations, size exclusion has proved to be the dominating mechanism for high rejections, and the ultralow friction water flow along g-C3N4 sheets is responsible for permeation enhancements. Importantly, the GO/g-C3N4 membrane shows promising long-term, antioxidation, and antipressure stability.

Theoretical design of two-dimensional Z-scheme photocatalysts for hydrogen production from water splitting.

Theoretical study on two-dimensional multilayered MXenes for hydrogen production from water splitting.