Theoretically designed two-dimensional γ-CO as an effective gas separation membrane for hydrogen purification.

A high-performance gas separation membrane for hydrogen (H) purification is still highly desirable for the sustainable development of our society. Based on the structure of γ-graphyne, we theoretically designed the two-dimensional nanomaterials γ-CX (X = O, S or Se) with intrinsic pores that may be suitable for gas separation. By first-principles calculations, we obtained the geometric structures of γ-CX, and confirmed that γ-CO and γ-CS are stable at room temperature.

Polymeric heptazine imide by O doping and constructing van der Waals heterostructures for photocatalytic water splitting: a theoretical perspective from transition dipole moment analyses.

Semiconductor-based photocatalysts have received extensive attention for their promising capacity in confronting global energy and environmental issues. In photocatalysis, a large band gap with suitable edge-position is necessary to warrant enough driving force for reaction, whereas a much smaller band gap is needed for visible-light response and high solar energy conversion efficiency. This paradox hinders the development of photocatalysts.

Two-Dimensional BAs/InTe: A Promising Tandem Solar Cell with High Power Conversion Efficiency.

Tandem solar cells (SCs) connecting two subcells with different absorption bands have the potential to reach the commercialized photovoltaic standard. However, the performance improvement of tandem architectures is still a challenge, primarily owing to the mismatch of band gaps in two subcells. Here, we demonstrate a two-dimensional (2D) BAs/InTe-based tandem SC, which could achieve solar-to-electric conversion efficiency higher than 30%.

Tunable Topological State, High Hole-Carrier Mobility, and Prominent Sunlight Absorbance in Monolayered Calcium Triarsenide.

Designing novel two-dimensional (2D) materials is highly desirable for material innovation. Here, we propose monolayered calcium triarsenide (1L CaAs) as a new 2D semiconductor with a series of encouraging functionalities. In contrast to the ∼33 meV small band gap in bulk CaAs, 1L CaAs possesses a large direct band gap of 0.

A remarkable two-dimensional membrane for multifunctional gas separation: halogenated metal-free fused-ring polyphthalocyanine.

We theoretically explore the structural and mechanical properties of metal-free fused-ring polyphthalocyanine (H2PPc) and halogenated H2PPc (F-H2PPc and Cl-H2PPc) membranes, and the energy profiles for gaseous H2, CO, CH4, CO2 and N2 molecules adsorbing on and passing through these monolayers. Importantly, we reconsider in depth the values of the parameters in the definition of permeance, and corroborate the validity of the model from first-principles theory with the results of H2 diffusion from classic molecular dynamics simulations. With well-defined nanosized pores, halogenated H2PPc monolayers turn out to be multifunctional gas separation membranes, i.

Confinement boosts CO oxidation on an Ni atom embedded inside boron nitride nanotubes.

To date, most studies of heterogeneous catalysis have focused on metal particles supported on the surface of substrates. However, studies of the catalytic properties of metallic nanoparticles supported on the interior surface of nanotubes are rare. Using first-principles calculations based on density functional theory, we have studied the CO oxidation on a single nickel atom confined in a nitrogen vacancy on the inside surface of boron nitride nanotubes (BNNT).

Ca-Embedded CN: an efficient adsorbent for CO capture.

Carbon dioxide as a greenhouse gas causes severe impacts on the environment, whereas it is also a necessary chemical feedstock that can be converted into carbon-based fuels via electrochemical reduction. To efficiently and reversibly capture CO, it is important to find novel materials for a good balance between adsorption and desorption. In this study, we performed first-principles calculations and grand canonical Monte Carlo (GCMC) simulations, to systematically study metal-embedded carbon nitride (CN) nanosheets for CO capture.

Nanoporous MoS monolayer as a promising membrane for purifying hydrogen and enriching methane.

We present a theoretical prediction of a highly efficient membrane for hydrogen purification and natural gas upgrading, i.e. laminar MoS material with triangular sulfur-edged nanopores.

Graphdiyne as a High-Efficiency Membrane for Separating Oxygen from Harmful Gases: A First-Principles Study.

We theoretically explored the adsorption and diffusion properties of oxygen and several harmful gases penetrating the graphdiyne monolayer. According to our first-principles calculations, the oxidation of the acetylenic bond in graphdiyne needs to surmount an energy barrier of ca. 1.

A promising monolayer membrane for oxygen separation from harmful gases: nitrogen-substituted polyphenylene.

We theoretically demonstrate that N-substitutional doping dramatically reduces the diffusion barrier for oxygen passing through the pores of polyphenylene, leading to a massive enhancement in O2 selectivity over various harmful gases with excellent permeance at appropriate temperatures for O2 across an N-doped polyphenylene in a unit cell.

Boron-substituted graphyne as a versatile material with high storage capacities of Li and H2: a multiscale theoretical study.

Based on density functional theory (DFT), first-principles molecular dynamics (MD), and the grand canonical ensemble Monte Carlo (GCMC) method, we investigated the boron substitution in aromatic rings of graphyne in terms of geometric and electronic structures as well as its bifunctional application including Li and H2 storage. The calculated binding energies of B-doped graphyne (BG) are significantly enhanced at two adsorptive sites compared to pristine graphyne, leading to high lithiation potentials of 2.7 V in 6Li@1BG, and even higher with 3.

Tunable band gap and hydrogen adsorption property of a two-dimensional porous polymer by nitrogen substitution.

After substitution of carbon by nitrogen, the electronic structures of the porous graphene have been studied by the density functional theory calculations. The N substitutional site without hydrogen passivation leads to a tunable energy gap of the two-dimensional porous polymer, depending on the number of N atoms in a unit cell. Moreover, the increasing number of N in an aromatic ring enhances the binding energies between hydrogen molecules and pre-adsorbed Li atoms from 1H(2) to 3H(2).