scholarly journals Band Engineering of Carbon Nitride Monolayers by N-Type, P-Type, and Isoelectronic Doping for Photocatalytic Applications

2018 ◽  
Vol 10 (13) ◽  
pp. 11143-11151 ◽  
Author(s):  
Meysam Makaremi ◽  
Sean Grixti ◽  
Keith T. Butler ◽  
Geoffrey A. Ozin ◽  
Chandra Veer Singh
Keyword(s):  
Carbon Nitride ◽  
Band Engineering ◽  
Isoelectronic Doping ◽  
P Type ◽  
Photocatalytic Applications

scholarly journals Strain Effects on the Electronic and Thermoelectric Properties of n(PbTe)-m(Bi2Te3) System Compounds

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4086
Author(s):  
Weiliang Ma ◽  
Marie-Christine Record ◽  
Jing Tian ◽  
Pascal Boulet
Keyword(s):  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Compressive Strain ◽  
Van Der Waals Interactions ◽  
Functional Theory ◽  
Band Engineering ◽  
Seebeck Coefficients ◽  
The Density Functional Theory ◽  
P Type ◽  
Narrow Band Gap Semiconductors

Owing to their low lattice thermal conductivity, many compounds of the n(PbTe)-m(Bi2Te3) homologous series have been reported in the literature with thermoelectric (TE) properties that still need improvement. For this purpose, in this work, we have implemented the band engineering approach by applying biaxial tensile and compressive strains using the density functional theory (DFT) on various compounds of this series, namely Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5. All the fully relaxed Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5 compounds are narrow band-gap semiconductors. When applying strains, a semiconductor-to-metal transition occurs for all the compounds. Within the range of open-gap, the electrical conductivity decreases as the compressive strain increases. We also found that compressive strains cause larger Seebeck coefficients than tensile ones, with the maximum Seebeck coefficient being located at −2%, −6%, −3% and 0% strain for p-type Bi2Te3, PbBi2Te4, PbBi4Te7 and Pb2Bi2Te5, respectively. The use of the quantum theory of atoms in molecules (QTAIM) as a complementary tool has shown that the van der Waals interactions located between the structure slabs evolve with strains as well as the topological properties of Bi2Te3 and PbBi2Te4. This study shows that the TE performance of the n(PbTe)-m(Bi2Te3) compounds is modified under strains.

scholarly journals Prediction of Band Gap Energy of Doped Graphitic Carbon Nitride Using Genetic Algorithm-Based Support Vector Regression and Extreme Learning Machine

Symmetry ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 411
Author(s):  
Taoreed O. Owolabi ◽  
Mohd Amiruddin Abd Rahman
Keyword(s):  
Genetic Algorithm ◽  
Visible Light ◽  
Band Gap ◽  
Carbon Nitride ◽  
Activation Function ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Support Vector ◽  
Learning Machine ◽  
Photocatalytic Applications

Graphitic carbon nitride is a stable and distinct two dimensional carbon-based polymeric semiconductor with remarkable potentials in organic pollutants degradation, chemical sensors, the reduction of CO2, water splitting and other photocatalytic applications. Efficient utilization of this material is hampered by the nature of its band gap and the rapid recombination of electron-hole pairs. Heteroatom incorporation due to doping alters the symmetry of the semiconductor and has been among the adopted strategies to tailor the band gap for enhancing the visible-light harvesting capacity of the material. Electron modulation and enhancement of reaction active sites due to doping as evident from the change in specific surface area of doped graphitic carbon nitride is employed in this work for modeling the associated band gap using hybrid genetic algorithm-based support vector regression (GSVR) and extreme learning machine (ELM). The developed GSVR performs better than ELM-SINE (with sine activation function), ELM-TRANBAS (with triangular basis activation function) and ELM-SIG (with sigmoid activation function) model with performance enhancement of 69.92%, 73.59% and 73.67%, respectively, on the basis of root mean square error as a measure of performance. The four developed models are also compared using correlation coefficient and mean absolute error while the developed GSVR demonstrates a high degree of precision and robustness. The excellent generalization and predictive strength of the developed models would ultimately facilitate quick determination of the band gap of doped graphitic carbon nitride and enhance its visible-light harvesting capacity for various photocatalytic applications.

scholarly journals Band Engineering and Morphology Control of Oxygen-Incorporated Graphitic Carbon Nitride Porous Nanosheets for Highly Efficient Photocatalytic Hydrogen Evolution

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Yunyan Wu ◽  
Pan Xiong ◽  
Jianchun Wu ◽  
Zengliang Huang ◽  
Jingwen Sun ◽  
...  
Keyword(s):  
Surface Area ◽  
Hydrogen Evolution ◽  
Carbon Nitride ◽  
Separation Efficiency ◽  
Physical Adsorption ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Photocatalytic Hydrogen Evolution ◽  
Band Engineering ◽  
Highly Efficient

AbstractGraphitic carbon nitride (g-C3N4)-based photocatalysts have shown great potential in the splitting of water. However, the intrinsic drawbacks of g-C3N4, such as low surface area, poor diffusion, and charge separation efficiency, remain as the bottleneck to achieve highly efficient hydrogen evolution. Here, a hollow oxygen-incorporated g-C3N4 nanosheet (OCN) with an improved surface area of 148.5 m2 g−1 is fabricated by the multiple thermal treatments under the N2/O2 atmosphere, wherein the C–O bonds are formed through two ways of physical adsorption and doping. The physical characterization and theoretical calculation indicate that the O-adsorption can promote the generation of defects, leading to the formation of hollow morphology, while the O-doping results in reduced band gap of g-C3N4. The optimized OCN shows an excellent photocatalytic hydrogen evolution activity of 3519.6 μmol g−1 h−1 for ~ 20 h, which is over four times higher than that of g-C3N4 (850.1 μmol g−1 h−1) and outperforms most of the reported g-C3N4 catalysts.

Rational nanostructure design of graphitic carbon nitride for photocatalytic applications

2019 ◽  
Vol 7 (19) ◽  
pp. 11584-11612 ◽  
Author(s):  
Na Tian ◽  
Hongwei Huang ◽  
Xin Du ◽  
Fan Dong ◽  
Yihe Zhang
Keyword(s):  
Carbon Nitride ◽  
Review Article ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Comprehensive Overview ◽  
Photocatalytic Applications

This review article provides a comprehensive overview of the nanostructure design of g-C3N4 with various dimensional structures and promising applications.

Energy band engineering and controlled p‐type conductivity of CuAlO2 thin films by nonisovalent Cu‐O alloying

2012 ◽  
Vol 100 (6) ◽  
pp. 062102 ◽  
Author(s):  
Z. Q. Yao ◽  
B. He ◽  
L. Zhang ◽  
C. Q. Zhuang ◽  
T. W. Ng ◽  
...  
Keyword(s):  
Thin Films ◽  
Energy Band ◽  
Type Conductivity ◽  
Band Engineering ◽  
P Type

Achieving high-performance p-type SmMg2Bi2 thermoelectric materials through band engineering and alloying effects

2020 ◽  
Vol 8 (31) ◽  
pp. 15760-15766 ◽  
Author(s):  
Udara Saparamadu ◽  
Xiaojian Tan ◽  
Jifeng Sun ◽  
Zhensong Ren ◽  
Shaowei Song ◽  
...  
Keyword(s):  
Power Generation ◽  
Thermoelectric Materials ◽  
High Performance ◽  
Promising Material ◽  
Band Engineering ◽  
P Type ◽  
Alloying Effects

P-type SmMg2Bi2, a new member of Bi-based 1-2-2 Zintl family, has been investigated and demonstrated to be a promising material for application in TE power generation.

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