The generalization of the Local Density Approximation (LDA) method for the systems with strong Coulomb correlations is presented which gives a correct description of the Mott insulators. The LDA+U method is based on the model hamiltonian approach and allows to take into account the non-sphericity of the Coulomb and exchange interactions. parameters. Orbital-dependent LDA+U potential gives correct orbital polarization and corresponding Jahn-Teller distortion. To calculate the spectra of the strongly correlated systems the impurity Anderson model should be solved with a many-electron trial wave function. All parameters of the many-electron hamiltonian are taken from LDA+U calculations. The method was applied to NiO and has shown good agreement with experimental photoemission spectra and with the oxygen Kα X-ray emission spectrum.

http://absimage.aps.org/image/MAR06/MWS_MAR06-2005-007233.pdf

First-principles calculations of electronic structure and spectra of strongly correlated systems: the LDA+U method

Photoreduction of N₂ is among the most interesting and challenging methods for N₂ fixation under mild conditions. In this study, we determined that nitrogen vacancies (NVs) could endow graphitic carbon nitride (g-C₃N₄) with the photocatalytic N₂ fixation ability. Photocatalytic N₂ fixation induced by NVs is free from the interference of other gases. The reason is that NVs could selectively adsorb and activate N₂ because NVs have the same shape and size as the nitrogen atom in N₂. In addition to this, NVs could also improve many other properties of g-C₃N₄ to support photocatalytic N₂ fixation. These new findings could elucidate the design of efficient photocatalysts for photocatalytic N₂ fixation.

Selective photocatalytic N₂ fixation dependent on g-C₃N₄ induced by nitrogen vacancies

Two-dimensional crystals have emerged as a class of materials that may impact future electronic technologies. Experimentally identifying and characterizing new functional two-dimensional materials is challenging, but also potentially rewarding. Here, we fabricate field-effect transistors based on few-layer black phosphorus crystals with thickness down to a few nanometres. Reliable transistor performance is achieved at room temperature in samples thinner than 7.5 nm, with drain current modulation on the order of 10(5) and well-developed current saturation in the I-V characteristics. The charge-carrier mobility is found to be thickness-dependent, with the highest values up to ∼ 1,000 cm(2) V(-1) s(-1) obtained for a thickness of ∼ 10 nm. Our results demonstrate the potential of black phosphorus thin crystals as a new two-dimensional material for applications in nanoelectronic devices.

http://absimage.aps.org/image/MAR14/MWS_MAR14-2013-005031.pdf

Black Phosphorus Field-effect Transistors

Signal propagation in complex networks

Carbon nitride polymers have emerged as a new class of materials for a wide range of applications such as photo- and electro-catalysis, sensors, bioimaging and more due to their chemical, photophysical and catalytic properties as well as their low-price, facile synthesis and high stability under harsh chemical conditions. In this review we begin with a broad overview of carbon-based materials, arriving at the focus of this review, polymeric carbon nitrides (CNs). After a brief overview of applications, we delve into their various synthetic methods, with an emphasis on achieving control on the nanoscale features of this intriguing polymeric semiconductor. The main synthetic pathways include co-polymerization at various stages, templating, an ionothermal pathway and harnessing of supramolecular pre-organization, which are discussed in detail along with CN growth and deposition on substrates. Finally, we give our perspectives on the evolution of this field, the current limitations, and elaboration of achievable control over the chemical composition, the electronic structure and the morphology of this family of materials.

/pdf/polymeric-carbon-nitrides-and-related-metal-free-materials-3koxy773bj.pdf

Polymeric carbon nitrides and related metal-free materials for energy and environmental applications

First-principles calculations have been carried out to investigate the possibility of B-, N-, Si-, and S-doped black phosphorus carbide monolayers (B-, N-, Si-, and S-bPCs) as efficient gas sensors to detect and eliminate toxic gas molecules such as NO2 and NH3. The influence of O2 and H2O has also been considered. It is found that O2, H2O, NO2, and NH3 are all physisorbed on N- and S-bPCs. Nevertheless, the moderate adsorption energy and large charge transfer of NO2 on N-bPC indicate that N-bPC is more suitable to detect NO2. The chemisorption is observed when NO2 and NH3 are adsorbed on B-bPC, and O2, NO2, and NH3 on Si-bPC, by which highly enhanced sensitivity toward these molecules can be realized. Due to the strong adsorption, B- and Si-bPCs can be used to detect and filter NO2 and NH3 at different working temperatures. The work function has been calculated to further interpret the adsorption mechanism. It increases with B and Si dopants and decreases with N and S dopants. The adsorption of molecules leads to different variations of the work function, which is correlated with the direction of charge transfer. Our theoretical investigations help us better understand the mechanism of bPC as a NO2 and NH3 gas sensor and provide a facile method to broaden its application in industrial, medical, and environmental monitoring.

A first-principles study of doped black phosphorus carbide monolayers as NO2 and NH3 sensors

The electrocatalytic N2 reduction reaction (NRR) is a very attractive yet challenging route for sustainable NH3 synthesis under ambient conditions, for which efficient catalysts are required due to the highly strong NN bond. In this work, B decorated C9N4 monolayer (B-C9N4) for NRR is studied by using first-principles calculations. It is found that the inert N2 can be sufficiently activated through the electron “acceptance-donation” pattern between N2 and the B dopant. The subsequent N2 reduction prefers the alternating mechanism, and the reduction of *N2 to *N2H is the potential-limiting step with an overpotential of 0.56 V. Furthermore, B-C9N4 exhibits a metallic nature, which can promote charge transfer during the reduction process. The stability of B-C9N4 can be confirmed by the calculated B adsorption energies and the ab initio molecular dynamic simulation. Consequently, owing to its high activity, good electrical conductivity, and excellent stability, B-C9N4 is a promising metal-free N2 reduction catalyst. Our work not only provides an efficient electrocatalyst for NH3 production, but also opens up a promising avenue to develop highly active and robust metal-free catalysts for other applications.

Boron-decorated C9N4 monolayers as promising metal-free catalysts for electrocatalytic nitrogen reduction reaction: a first-principles study

The nuclear symmetry energy coefficients of finite nuclei are extracted by using the differences between the masses of isobaric nuclei. Based on the masses of more than 2400 nuclei with A = 10‐270, we investigate the modeldependenceintheextractionofthesymmetryenergycoefficient.Wefindthattheextractionofthesymmetry energy coefficients is strongly correlated with the forms of the Coulomb energy and the mass dependence of the symmetry energy coefficient adopted. The values of the extracted symmetry energy coefficients increase by about 2 MeV for heavy nuclei when the Coulomb correction term is involved. The values of the bulk symmetry energy coefficient S0 and the surface-to-volume ratio κ are simultaneously investigated based on the extracted symmetry energy coefficients.

Effect of Coulomb energy on the symmetry energy coefficients of finite nuclei

Transition metal (TM) and nitrogen co-doped carbon (T M-N -C) materials have emerged as the promising single-atom catalyst (SAC) for the electrocatalytic CO2 reduction reaction (CO2RR), for which the coordination environment of the anchored single atom plays an important role. Inspired by this, the C3N monolayers embedded with the TM single atoms at the C C double vacancy, denoted as M-CC (M Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au), have been evaluated for CO2RR by using the first-principles calculation. We find that the M-CC SACs are of high stability and metallic conductivity, beneficial for the electron transport during the electrocatalytic process. More importantly, all M-CC have high selectivity toward CO2RR versus the hydrogen evolution reaction. Especially, Cu-, Co-, Fe-, and Mn-CC have acceptable or ultra-low limiting potentials of −0.68, −0.48, −0.83, and −0.24 V to produce HCOOH, CH2O, CH3OH, and CH4, respectively. The catalytic activities of M-CC are correlated with the adsorption strength of the key intermediates, further rationalized by the bonding/antibonding population analysis. Our work proposes a new material platform to realize TM-C-N SACs for efficiently electrocatalytic CO2RR, which could provide useful insights into the design of such catalysts.

CO2 electroreduction by transition metal-embedded two-dimensional C3N: A theoretical study

Modulating electronic and optical properties of black phosphorous carbide monolayers by molecular doping

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Junlong Tian

Author Tools

Chat about Author