As an excellent clean medium for hydrogen storage and fuel cell applications, the photolysis of ammonia via localized surface plasmon could be invoked as a promising route towards significantly reducing the temperature for conventional thermolysis. Here, we explore the underlying microscopic mechanism of ultrafast carrier dynamics in plasmon-mediated NH₃ photodecomposition at the single-molecular level using real-time time-dependent density functional theory. The NH₃ molecule adsorbed on the tip of archetypal magic metal clusters represented by tetrahedral Ag₂₀ and icosahedral Ag₁₄₇, splits within a hundred femtoseconds upon laser pulse illumination. We found that the splitting of the first N-H bond is dominated by the intramolecular charge transfer driven by localized surface plasmon. Surprisingly, the phase of laser pulse could modulate the dynamics of charge transfer and thus affect the plasmon-induced bond breaking. These findings offer a new avenue for NH₃ decomposition and provide in-depth insights in designing highly efficient plasmon-mediated photocatalysts.

Chiral switching is a fascinating topic and plays an important role in construction of homochirality. Nevertheless, due to the complexity and flexibility of noncovalent interactions, switching the chirality of entire supramolecular assemblies has hitherto remained a challenge. Here we report the electric field-controlled chirality switching of pentacene pinwheel arrays and two-dimensional (2D) network domains. Pentacene molecules on Cd(0001) surface form the porous network structure with building blocks of hexamer pinwheels. Driven by the electric field from a scanning tunneling microscopy (STM) tip, the supramolecular chirality of pentacene pinwheels and the organizational chirality of entire network domains can be simultaneously switched from one enantiomorph to another. Furthermore, such chiral switching is reversible and repeatable under successive voltage pulses. First-principles calculations demonstrate that electric field significantly modulates the interfacial charge transfer and induces the Coulomb expansion of pentacene layers, and the subsequent reaggregation leads to the chiral flipping of the supramolecular pinwheels and 2D domains. Our results provide a new strategy for dynamic control of the 2D chiral structures and help to steer the supramolecular assembly toward homochirality.

Two-dimensional (2D) magnetic crystals have been extensively explored thanks to their potential applications in spintronics, valleytronics, and topological superconductivity. Here we report a novel monolayer magnet, namely puckered pentagonal VTe₂ (PP-VTe₂), intriguing atomic and electronic structures of which were firmly validated from first-principles calculations. The PP-VTe₂ exhibits strong intrinsic ferromagnetism and semiconducting property distinct from the half-metallic bulk pyrite VTe₂ (BP-VTe₂) phase. An unusual magnetic anisotropy with large magnetic exchange energies is found. More interestingly, the multiferroic coupling between its 2D ferroelasticity and in-plane magnetization is further identified in PP-VTe₂, lending it unprecedented controllability with external strains and electric fields. Serving as an emergent 2D ferromagnetic semiconductor with a novel crystal structure, monolayer PP-VTe₂ provides an ideal platform for exploring exotic crystalline and spin configurations in low-dimensional systems.

Ab initio and classical molecular dynamics simulations show that water can flow through graphdiyne—an experimentally fabricated graphene-like membrane with highly dense (2.4 × 10¹⁸ pores/m²), uniformly ordered, subnanometer pores (incircle diameter 0.57 nm and van der Waals area 0.06 nm²). Water transports through subnanopores via a chemical-reaction-like activated process. The activated water flow can be precisely controlled through fine adjustment of working temperature and pressure. In contrast to a linear dependence on pressure for conventional membranes, here pressure directly modulates the activation energy, leading to a nonlinear water flow as a function of pressure. Consequently, high flux (1.6 L/Day/cm²/MPa) with 100% salt rejection efficiency is achieved at reasonable temperatures and pressures, suggesting graphdiyne can serve as an excellent membrane for water desalination. We further show that to get through subnanopores water molecule must break redundant hydrogen bonds to form a two-hydrogen-bond transient structure. Our study unveils the principles and atomistic mechanism for water transport through pores in ultimate size limit, and offers new insights on water permeation through nanochannels, design of molecule sieving and nanofluidic manipulation.

Rapid developments in both fundamental science and modern technology that target water-related problems, including the physical nature of our planet and environment, the origin of life, energy production via water splitting, and water purification, all call for a molecular-level understanding of water. This invokes relentless efforts to further our understanding of the basic science of water. Current challenges to achieve a molecular picture of the peculiar properties and behavior of water are discussed herein, with a particular focus on the structure and dynamics of bulk and surface water, the molecular mechanisms of water wetting and splitting, application-oriented research on water decontamination and desalination, and the development of complementary techniques for probing water at the nanoscale.

Molecular heterojunctions, such as the one based on copper phthalocyanine (CuPc) and carbon fullerene (C₆₀) molecules, are commonly employed in organic photovoltaic cells as electron donor–acceptor pairs. We have investigated the different atomic structures and electronic and optical properties of the C₆₀/CuPc heterojunction through first-principles calculations based on density functional theory (DFT) and time-dependent DFT. In general, configurations with the CuPc molecule "lying down" on C₆₀ are energetically more favorable than configurations with the CuPc molecule "standing up". The lying-down configurations also facilitate charge transfer between the two molecules, due to the stronger interaction and the larger overlap between electronic wavefunctions at the interface. The energetically preferred structure consists of CuPc placed so that the Cu atom is above a bridge site of C₆₀, with one N–Cu–N bond of CuPc being parallel to a C–C bond of C₆₀. We also considered the structure of a periodic CuPc monolayer deposited on the (001) surface of a face-centered cubic (fcc) crystal of C₆₀ molecules with the lying-down orientation and on the (111) surface with the standing-up configuration. We find that the first arrangement can lead to larger open circuit voltage due to an enhanced electronic interaction between CuPc and C₆₀ molecules.