scholarly journals Effect of Electronegativity and Charge Balance on the Visible-Light-Responsive Photocatalytic Activity of Nonmetal Doped Anatase TiO2

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Jibao Lu ◽  
Hao Jin ◽  
Ying Dai ◽  
Kesong Yang ◽  
Baibiao Huang
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Density Functional ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Charge Balance ◽  
Functional Theory ◽  
Impurity States ◽  
Photocatalytic Activities ◽  
Visible Light Photocatalytic

The origin of visible light absorption and photocatalytic activity of nonmetal doped anatase TiO2were investigated in details in this work based on density functional theory calculations. Our results indicate that the electronegativity is of great significance in the band structures, which determines the relative positions of impurity states induced by the doping species, and further influences the optical absorption and photocatalytic activities of doped TiO2. The effect of charge balance on the electronic structure was also discussed, and it was found that the charge-balance structures may be more efficient for visible light photocatalytic activities. In addition, the edge positions of conduction band and valence band, which determine the ability of a semiconductor to transfer photoexcited electrons to species adsorbed on its surface, were predicted as well. The results may provide a reference to further experimental studies.

Enhanced visible light photocatalytic activity of anatase TiO2 through C, N, and F codoping

2014 ◽  
Vol 92 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Zongbao Li ◽  
Wang Xia ◽  
Lichao Jia
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Density Functional ◽  
Light Response ◽  
Anatase Tio2 ◽  
Functional Theory ◽  
Visible Light Response ◽  
Elemental Doping ◽  
Visible Light Photocatalytic ◽  
Good Agreement

The electronic and optical properties of pure, C-doped, (C, F)-codoped, (C, N)-codoped, and (C, N, F)-codoped anatase TiO2 are investigated by using density functional theory (DFT). The results indicate that elemental doping creates a much more efficient and stable photocatalyst than pristine, which narrows the band gap of TiO2 and realizes its visible light response activity. With the incorporation of F into (C, N)-codoped TiO2, strong visible light absorption and photocatalytic activity are further increased. It also verifies the reliability of our calculations for good agreement with the experimental results in the optical absorption of (C, N)-codoped and (C, N, F)-codoped.

(Cu, Ag)-DOPED ZnS WITH WIDE VISIBLE LIGHT RANGE ABSORPTION FOR WATER SPLITTING: A THEORETICAL AND EXPERIMENTAL STUDY

2019 ◽  
Vol 27 (04) ◽  
pp. 1950139
Author(s):  
XIAOBO CHEN ◽  
WEIWEI LIU ◽  
ZHIHAI ZHANG ◽  
WEN YANG ◽  
PEIZHI YANG
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Density Functional ◽  
Energy Levels ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Functional Theory ◽  
Light Region

Photocatalytic water splitting using a semiconductor photocatalyst is a promising process for direct solar energy conversion. In this study, the feasibility of the photocatalytic H2 evolution on (Cu, Ag)- doped ZnS catalysts under visible light irradiation has been investigated by using first-principles density functional theory calculations and experimental studies. The present results reveal that (Cu, Ag)-doped ZnS structures have relatively small formation energy, implying that they are more easily obtained in experiment. Moreover, the absorption is enhanced obviously in the visible-light region for (Cu, Ag)-doped ZnS, but their energy levels are still suitable for water splitting to generate H2, which means that (Cu, Ag)-doped ZnS structures are promising candidate photocatalyst materials for H2 production driven by visible light. ZnS and (Cu, Ag)-doped ZnS were prepared using chemical precipitation method. (Cu, Ag)-doped ZnS samples showed an improved photocatalytic activity compared with undoped ZnS. Ag-doped ZnS (0.15 g L[Formula: see text] has the highest hydrogen evolution rate of 794.6 [Formula: see text]mol[Formula: see text] h[Formula: see text] [Formula: see text] g[Formula: see text] at pH 3 (0.1 M Na2S solution as a sacrificing agent).

scholarly journals Band gap narrowing in nitrogen-doped La2Ti2O7 predicted by density-functional theory calculations

2015 ◽  
Vol 17 (14) ◽  
pp. 8994-9000 ◽  
Author(s):  
Junying Zhang ◽  
Wenqiang Dang ◽  
Zhimin Ao ◽  
Scott K. Cushing ◽  
Nianqiang Wu
Keyword(s):  
Density Functional Theory ◽  
Photocatalytic Activity ◽  
Band Gap ◽  
Density Functional ◽  
Energy State ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Nitrogen Doped ◽  
Band Gap Narrowing ◽  
Visible Light Photocatalytic

NS co-existing with VO in La2Ti2O7 narrows the band gap and removes the localized energy state, leading to a strong visible light photocatalytic activity and enhancement of the UV performance.

First-Principle Study of Electronic Structure and Enhanced Visible-Light Photocatalytic Activity of Anatase TiO2 through C and F Codoping

2013 ◽  
Vol 746 ◽  
pp. 400-405 ◽  
Author(s):  
Zong Bao Li ◽  
Xia Wang
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Band Gap ◽  
Density Functional ◽  
Light Response ◽  
Functional Theory ◽  
Visible Light Photocatalytic Activity ◽  
Visible Light Response ◽  
The Density Functional Theory ◽  
Visible Light Photocatalytic

The large intrinsic band gap in TiO2has hindered severely its potential application for visible-light irradiation, while anion doping has led to decreases in visible-light photocatalytic activity in spite of narrowing the host band gap. In this study, we have used cation-passivated codoping of (C, F), (C, 2F) and (2C, F) to modify the band edges of anatase TiO2to extend absorption to longer visible-light wavelegenths using the density functional theory based on GGA + U method. The results indicate that the codoping of C/F=1/1 cases have much more efficient and stable photocatalyst than pristine one and the others, which narrow the band gaps and realize the visible-light response activities.

scholarly journals Enhancement of Titania Photoanode Performance by Sandwiching Copper between Two Titania Layers

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4326
Author(s):  
Fan Yang ◽  
Ruizhuang Yang ◽  
Lin Yan ◽  
Jiankun Wu ◽  
Xiaolin Liu ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Sandwich Structure ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Light Response ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Tio2 Lattice ◽  
Novel Method ◽  
Cu Dopant

Vacancies in semiconductors can play a versatile role in boosting their photocatalytic activity. In this work, a novel TiO2/Cu/TiO2 sandwich structure is designed and constructed. Abundant vacancies were introduced in TiO2 lattice by Cu reduction under heat treatment. Meanwhile, Cu atom could diffuse into TiO2 to form Cu-doped TiO2. The synergistic effect between oxygen vacancies and Cu atoms achieved about 2.4 times improved photocurrent of TiO2/Cu/TiO2 sandwich structure compared to bare TiO2 thin film. The enhanced photoactivity may be attributed to regulated electron structure of TiO2 by oxygen vacancies and Cu dopant from experimental results and density functional theory calculations. Oxygen vacancies and Cu dopant in TiO2 formed through copper metal reduction can introduce impurity levels and narrow the band gap of TiO2, thus improve the visible light response. More importantly, the Cu2+ and oxygen vacancies in TiO2 lattice can dramatically increase the charge density around conduction band and promote separation of photo-induced charge carriers. Furthermore, the oxygen vacancies on the surface may serve as active site for sufficient chemical reaction. This work presents a novel method to prepare doped metal oxides catalysts with abundant vacancies for improving photocatalytic activity.

scholarly journals Influence of Varying Functionalization on the Peroxidase Activity of Nickel(II)–Pyridine Macrocycle Catalysts: Mechanistic Insights from Density Functional Theory

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 52
Author(s):  
Jerwin Jay E. Taping ◽  
Junie B. Billones ◽  
Voltaire G. Organo
Keyword(s):  
Density Functional Theory ◽  
Proton Transfer ◽  
Density Functional ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Stoichiometric Ratio ◽  
Functional Theory ◽  
Pendant Arm ◽  
Spin Singlet

Nickel(II) complexes of mono-functionalized pyridine-tetraazamacrocycles (PyMACs) are a new class of catalysts that possess promising activity similar to biological peroxidases. Experimental studies with ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), substrate) and H2O2 (oxidant) proposed that hydrogen-bonding and proton-transfer reactions facilitated by their pendant arm were responsible for their catalytic activity. In this work, density functional theory calculations were performed to unravel the influence of pendant arm functionalization on the catalytic performance of Ni(II)–PyMACs. Generated frontier orbitals suggested that Ni(II)–PyMACs activate H2O2 by satisfying two requirements: (1) the deprotonation of H2O2 to form the highly nucleophilic HOO−, and (2) the generation of low-spin, singlet state Ni(II)–PyMACs to allow the binding of HOO−. COSMO solvation-based energies revealed that the O–O Ni(II)–hydroperoxo bond, regardless of pendant arm type, ruptures favorably via heterolysis to produce high-spin (S = 1) [(L)Ni3+–O·]2+ and HO−. Aqueous solvation was found crucial in the stabilization of charged species, thereby favoring the heterolytic process over homolytic. The redox reaction of [(L)Ni3+–O·]2+ with ABTS obeyed a 1:2 stoichiometric ratio, followed by proton transfer to produce the final intermediate. The regeneration of Ni(II)–PyMACs at the final step involved the liberation of HO−, which was highly favorable when protons were readily available or when the pKa of the pendant arm was low.

0D/3D-CdSe/Bi12TiO20 Pyramidal Heterostructure Photocatalysts for Enhanced Visible-Light Photocatalytic Activities

NANO ◽  
2017 ◽  
Vol 12 (06) ◽  
pp. 1750072 ◽  
Author(s):  
Tao Wang ◽  
Changchang Ma ◽  
Dan Wu ◽  
Xinlin Liu ◽  
Yang Liu ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
High Stability ◽  
Photocatalytic Efficiency ◽  
Cdse Qds ◽  
Electron Hole ◽  
Adsorption Sites ◽  
Photocatalytic Activities ◽  
Visible Light Photocatalytic

In this paper, a novel heterostructure of 0D/3D-CdSe/Bi[Formula: see text]TiO[Formula: see text] pyramidal photocatalyst was synthesized and characterized. It exhibited significantly photocatalytic efficiency in photocatalytic degradation of the tetracycline than pure Bi[Formula: see text]TiO2 and CdSe and showed high stability. The enhanced photocatalytic activity might be attributed to the formation of heterostructure between CdSe QDs and 3D Bi[Formula: see text]TiO[Formula: see text], in which CdSe QDs served as electron trapper to improve the separation of photodegradation electron–hole pairs, and provided a number of active adsorption sites for the photogenerated of pollutants. The photocatalytic mechanism of 0D/3D-CdSe/Bi[Formula: see text]TiO[Formula: see text] pyramidal heterostructure was also proposed.

Novel carbon dots/BiOBr nanocomposites with enhanced UV and visible light driven photocatalytic activity

RSC Advances ◽  
2015 ◽  
Vol 5 (39) ◽  
pp. 31057-31063 ◽  
Author(s):  
Qingqing Du ◽  
Wenpeng Wang ◽  
Yongzhong Wu ◽  
Gang Zhao ◽  
Fukun Ma ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Carbon Dots ◽  
Photocatalytic Activities ◽  
Visible Light Driven ◽  
Visible Light Photocatalytic

Novel CD/BiOBr nanocomposites were prepared and both UV and visible light photocatalytic activities were enhanced.

A hybrid density functional study on the visible light photocatalytic activity of (Mo,Cr)–N codoped KNbO3

2015 ◽  
Vol 17 (43) ◽  
pp. 28743-28753 ◽  
Author(s):  
Guangzhao Wang ◽  
Hong Chen ◽  
Yang Li ◽  
Anlong Kuang ◽  
Hongkuan Yuan ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Density Functional ◽  
Photocatalytic Performance ◽  
Functional Study ◽  
Redox Level ◽  
Hybrid Density Functional ◽  
Decomposition Of Water ◽  
Visible Light Photocatalytic

To improve the photocatalytic performance of KNbO3 for the decomposition of water into hydrogen and oxygen, the electronic structure of KNbO3 should be modified to have a suitable bandgap with band edge positions straddling the water redox level so as to sufficiently absorb visible light.

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