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...