NiO nanoparticle surface energy studies using first principles calculations

2018 ◽  
Vol 42 (13) ◽  
pp. 10791-10797 ◽  
Author(s):  
Junxiang Xiang ◽  
Bin Xiang ◽  
Xudong Cui
Keyword(s):  
Surface Energy ◽  
First Principles ◽  
Active Sites ◽  
Practical Importance ◽  
Catalytic Efficiency ◽  
First Principles Calculations ◽  
Miller Index ◽  
Surface Energies ◽  
Nanoparticle Surface

Understanding the correlations between active sites and surface energies of Miller index surfaces is of practical importance to get insights into catalytic efficiency.

SURFACE ENERGY ENGINEERING OF Cu SURFACE BY STRAIN: FIRST-PRINCIPLES CALCULATIONS

2013 ◽  
Vol 20 (06) ◽  
pp. 1350054 ◽  
Author(s):  
L. HE ◽  
Y. W. LIU ◽  
W. J. TONG ◽  
J. G. LIN ◽  
X. F. WANG
Keyword(s):  
Surface Energy ◽  
First Principles ◽  
Strain Distribution ◽  
First Principles Calculations ◽  
Surface Energies ◽  
Energy Engineering

Surface energies of strained Cu surfaces were studied systematically using first-principles methods. Results showed that the strain-stabilization of Cu surface was anisotropic and strongly related to the strain distribution. This strain-induced approach could be used as an effective way to engineer the surface energies of metals.

The Influence of Surface Reconstruction and C-impurities on Photocatalytic Water Dissociation by TiO2

2003 ◽  
Vol 801 ◽  
Author(s):  
Xiliang Nie ◽  
Karl Sohlberg
Keyword(s):  
Surface Energy ◽  
Band Gap ◽  
First Principles ◽  
Active Sites ◽  
Water Dissociation ◽  
First Principles Calculations ◽  
Surface Band ◽  
Carbon Doped ◽  
Carbon Impurities ◽  
Photoabsorption Spectrum

ABSTRACTTiO2 is well known as a prototype photocatalyst for water dissociation. To understand the mechanism of its photocatalytic water dissociation we performed first-principles calculations. We find that the surface of the catalytically favorable (TiO) termination is very different from the physically favorable (oxygen) termination. The calculated surface energy of the catalytically favorable (TiO) termination is about 10 times larger than that of the physically favorable (oxygen) termination. Analysis of the surface band structure suggests that while O-vacancies are intrinsic active sites for water dissociation into H2 and O2 gas, they are not essential for photocatalytic water dissociation. We also find that carbon impurities decrease the band-gap of TiO2, in agreement with previously reported experimental results. Moreover, we identify the origin of the arcane “double band gap” in carbon doped TiO2. The two onsets seen in the photoabsorption spectrum result from excitations from two of three C p-states within the band gap, not from domains of different composition.

First-Principles Study on the Surface Energies of Rutile TiO2(110) vs (011)-2×1 Surfaces

2014 ◽  
Vol 937 ◽  
pp. 113-117
Author(s):  
Feng Yuan ◽  
Shi Xiang Lu ◽  
Wen Guo Xu ◽  
Hai Feng Zhang ◽  
Tao Ning
Keyword(s):  
Density Functional Theory ◽  
Surface Energy ◽  
Linear Relationship ◽  
First Principles ◽  
Density Functional ◽  
Slab Thickness ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Surface Energies ◽  
Number Of Layers

First-principles calculations based on density functional theory have been used to study the surface energies of the rutile TiO2(110) and (011)-2×1 surfaces. We investigate the effect of the slab thickness on the predicted surface energy and find that slab thicknesses of at least 5 layers are necessary to converge the surface energy to within 0.01 J/m2for both rutile TiO2(110) and (011)-2×1 surfaces. For the rutile TiO2(110) surface, it should be noted that the surface energy oscillates with the number of layers (odd-even oscillations). However, the calculated surface energies of the rutile TiO2(011)-2×1 surface are closer to the linear relationship for the number of layers larger than 4. Finally, our calculated results indicate that the rutile TiO2(011)-2×1 surface has a significantly higher surface energy than the rutile TiO2(110) surface.

Effects of finite temperature on the surface energy in Al alloys from first-principles calculations

2019 ◽  
Vol 479 ◽  
pp. 499-505
Author(s):  
Zhipeng Wang ◽  
Dongchu Chen ◽  
Qihong Fang ◽  
Hong Chen ◽  
Touwen Fan ◽  
...  
Keyword(s):  
Surface Energy ◽  
First Principles ◽  
Finite Temperature ◽  
Al Alloys ◽  
First Principles Calculations

First-Principles Study of Nanofacet Formation on 4H-SiC(0001) Surface

2014 ◽  
Vol 778-780 ◽  
pp. 201-205
Author(s):  
Keisuke Sawada ◽  
Jun Ichi Iwata ◽  
Atsushi Oshiyama
Keyword(s):  
Surface Energy ◽  
Total Energy ◽  
First Principles ◽  
Atomic Layer ◽  
First Principles Calculations ◽  
Atomic Structures ◽  
First Principles Study ◽  
Energy Variation ◽  
The Difference ◽  
Facet Formation

We perform the first-principles calculations on the 4H-SiC(0001) surface and clarify the mechanism of the facet formation. We first identify atomic structures of single-, double- and quadribilayer steps and find that the single-bilayer (SB) step has the lowest total energy among these three step structures. Then, we reveal that the nanofacet consisting of SB steps is more energetically stable than the equally spaced SB step and the surface-energy variation caused by the difference of stacking sequences of the bi-atomic layer near the surface is an important factor of the facet formation.

Fe-doped Bi4O5Br2 visible light photocatalyst: A first principles investigation

2018 ◽  
Vol 17 (05) ◽  
pp. 1850031 ◽  
Author(s):  
Weibin Zhang ◽  
Gangqiang Zhu ◽  
Woochul Yang ◽  
Qijun Sun ◽  
Qingfeng Wu ◽  
...  
Keyword(s):  
Surface Energy ◽  
Band Gap ◽  
First Principles ◽  
Active Sites ◽  
Photon Absorption ◽  
Relative Mass ◽  
Energy Calculation ◽  
Fe Doping ◽  
Photocatalytic Efficiency ◽  
Key Factors

This study employed first principles calculations to investigate Fe-doped Bi4O5Br2 as a potential photocatalyst with high efficiency. Based on formation energy calculation, the Fe atoms prefer to replace the Bi atoms with coordination bond of 3, and the optimal concentration for Fe-doping is 6.06[Formula: see text]wt.%. From surface energy calculations, the [Formula: see text] surface has the lowest surface energy, and therefore the easiest cleavage facet is [Formula: see text]. The key factors for the improvement of photocatalytic efficiency after Fe-doped Bi4O5Br2 are estimated as follows. First, the band gap decreases from 2.63[Formula: see text]eV in pristine case to 2.40[Formula: see text]eV in 4 Fe-doped Bi4O5Br2 case, resulting in the photon absorption edge shift to lower energy range and the absorption coefficient increase. Secondly, the work functions decrease from 5.66 eV (pristine) to 4.92[Formula: see text]eV (4 Fe-doped Bi4O5Br2), which facilitate the electrons escaping from the surface. Thirdly, the relative mass ratio of photo-induced electrons and holes increases with Fe concentration. Because the Fe 3[Formula: see text] impurity states in the forbidden band gap become wider, the relative ratio increased after Fe-doped Bi4O5Br2. Finally, the Fe doping process introduces more active sites on the surface, which can effectively improve the capacity of target molecules adsorption. Therefore, it is reasonable to believe that Fe-doped Bi4O5Br2 can effectively improve the photocatalytic efficiency because the abovementioned key factors have tremendously improved. Our work provides a reasonable reason for choosing Fe as a dopant, which can help our experimental work and provide explanation for photocatalytic efficiency improvement.

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