scholarly journals Function ofTiO2Lattice Defects toward Photocatalytic Processes: View of Electronic Driven Force

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Huanan Cui ◽  
Hong Liu ◽  
Jianying Shi ◽  
Chuan Wang
Keyword(s):  
Active Sites ◽  
High Performance ◽  
Great Influence ◽  
Heterogeneous Photocatalysis ◽  
Charge Carriers ◽  
Energy Structure ◽  
Practical Applications ◽  
Short Range Force ◽  
Surface Active ◽  
Photocatalytic Reactions

Oxygen vacancies and Ti-related defects (OTDs) are the main lattice defects ofTiO2, which have great influence on its photocatalytic activity. To understand the relationship between the defects and photocatalytic activities, detailed discussions based on the electronic driven force provided by these defects are carried out during the three commonly accepted processes in photocatalytic reactions. It is found that these defects inevitably (i) influence the energy structure of the pristineTiO2as the isolate acceptor/donor level or hybrid with the original orbital, (ii) provide a disordered short-range force that confuses the charge carriers transferring to surface active sites, (iii) act not only as the surface active sites for trapping the charge carriers but also as the main chemisorption sites forO2,H2O, and organic species. These effects of the defects make them one of the key factors that determine the efficiency of heterogeneous photocatalysis. Clarifying the role of the defects will further facilitate the exploration and the construction of high-performance photocatalysts for practical applications.

Role of the Structure and Electronic Properties of Fe2O3-MoO3 Catalyst on the Dehydration of Isopropyl Alcohol

1993 ◽  
Vol 58 (7) ◽  
pp. 1591-1599 ◽  
Author(s):  
Abd El-Aziz A. Said
Keyword(s):  
Active Sites ◽  
Isopropyl Alcohol ◽  
Oxide Catalyst ◽  
Flow System ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalyst Composition ◽  
Surface Active

Molybdenum oxide catalyst doped or mixed with (1 - 50) mole % Fe3+ ions were prepared. The structure of the original samples and the samples calcined at 400 °C were characterized using DTA, X-ray diffraction and IR spectra. Measurements of the electrical conductivity of calcined samples with and without isopropyl alcohol revealed that the conductance increases on increasing the content of Fe3+ ions up to 50 mole %. The activation energies of charge carriers were determined in presence and absence of the alcohol. The catalytic dehydration of isopropyl alcohol was carried out at 250 °C using a flow system. The results obtained showed that the doped or mixed catalysts are active and selective towards propene formation. However, the catalyst containing 40 mole % Fe3+ ions exhibited the highest activity and selectivity. Correlations were attempted to the catalyst composition with their electronic and catalytic properties. Probable mechanism for the dehydration process is proposed in terms of surface active sites.

scholarly journals Enhancement of Photocatalytic Activity under Visible Light Irradiation via the AgI@TCNQ Core-Shell Structure

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1679 ◽  
Author(s):  
Wanli Xie ◽  
Li Liu ◽  
Wenquan Cui ◽  
Weijia An
Keyword(s):  
Shell Structure ◽  
Active Sites ◽  
Photocatalytic Performance ◽  
Degradation Process ◽  
Charge Carriers ◽  
Core Shell ◽  
Transport Channel ◽  
Surface Active ◽  
Core Shell Structure ◽  
Unique Core

In this paper, a AgI@TCNQ photocatalyst with a core-shell structure was reported. A two-dimensional TCNQ (7,7,8,8-Tetracyanoquinodimethane) nanosheet, with a π-π conjugate structure, was used as a shell layer to realize the flexible coating on the surface of AgI nanoparticles. These special core-shell structure composites solve the key problems of the small interface of the bulk composites and the lesser charge transfer paths, which could accelerate the migration of photogenerated carriers. Thus, the AgI@TCNQ photocatalysts showed the better photodegradation performance for the methylene blue (MB) solution, and the degradation rate of AgI@TCNQ (1 wt.%) composite was 1.8 times than AgI under irradiation. The reactive species trapping experiments demonstrated that ·O2−, h+, and ·OH all participated in the MB degradation process. The photocatalytic mechanism of AgI@TCNQ composites could be rationally explained by considering the Z-scheme structure, resulting in a higher redox potential and more efficient separation of charge carriers. At the same time, the unique core-shell structure provides a larger contact area, expands the charge transport channel, and increases the surface active sites, which are beneficial for improving photocatalytic performance.

Facile synthesis of hierarchical Ni7S6 and Co(ii)-doped Ni7S6 flower structures for high-performance supercapacitors

2020 ◽  
Vol 44 (10) ◽  
pp. 3896-3902 ◽  
Author(s):  
Daojun Zhang ◽  
Xueying Fu ◽  
Xiaobei Zhang ◽  
Chengxiang Li ◽  
Hao Bian ◽  
...  
Keyword(s):  
Alkaline Solution ◽  
Active Sites ◽  
High Performance ◽  
Facile Synthesis ◽  
Supercapacitor Performance ◽  
Surface Active ◽  
Flower Structures

The as-prepared flower-like Ni7S6 structure with abundant surface active sites demonstrated good supercapacitor performance in an alkaline solution.

Inactivation and Regeneration of Photocatalytic Properties of ZnO Nanofilm Materials

2012 ◽  
Vol 531 ◽  
pp. 199-202 ◽  
Author(s):  
Han Shui Wu ◽  
Ying Lian Wang
Keyword(s):  
Thin Films ◽  
Active Sites ◽  
Sol Gel ◽  
Photocatalytic Properties ◽  
Zno Thin Films ◽  
Glass Substrates ◽  
Degradation Rates ◽  
Sol Gel Process ◽  
Surface Active ◽  
Photocatalytic Reactions

Highly photoactive ZnO thin films have been prepared by sol-gel process on glass substrates. The influence of annealing temperatures on degradation rates has been studied, the inactivation and regeneration of photocatalytic properties of ZnO thin films have also been further discussed. The results show that the best annealing temperature is 300oC, surface active sites of new prepared thin films will be passive after the first photocatalytic reactions, photocatalytic performance successively reduced. H2O2 processed films can make the photocatalytic activity basically return to the level of new prepared films, can satisfy the need of repetitive use.

3D hierarchical nanoarrays composed of NiCo-Te multilayer nanoneedles modified with Co1.29Ni1.71O4 for high-performance hybrid supercapacitors

2021 ◽  
Author(s):  
Chao Shi ◽  
Qingjun Yang ◽  
Chengyu Deng ◽  
Shengyu Chen ◽  
Yue Hao ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Transition Metal ◽  
Active Sites ◽  
High Performance ◽  
Hybrid Supercapacitors ◽  
Surface Active ◽  
Limited Surface ◽  
Capacity Performance ◽  
Electrodes For Supercapacitors

Transition metal tellurides have been developed as electrodes for supercapacitors, owing to the high pseudocapacitance and excellent electrical conductivity. However, the limited surface-active sites limits the improvement of capacity performance....

Quantifying the photocatalytic role and activity at the edge and surface of Pd co-catalysts using N2 fixation as a case

2021 ◽  
Author(s):  
Shijie Wu ◽  
Jiafei Zhang ◽  
Wenbin Chen ◽  
Pingxing Xing ◽  
Xingchen Liu ◽  
...  
Keyword(s):  
N2 Fixation ◽  
Active Sites ◽  
High Performance ◽  
Design And Development ◽  
Co Catalysts ◽  
Catalytic Role ◽  
Photocatalytic Reactions

To quantitatively evaluate the catalytic role and activity of different active sites of catalysts in photocatalytic reactions is of great significance for the design and development of high-performance photocatalysts. However,...

scholarly journals Influence of the Facets of Bi24O31Br10 Nanobelts and Nanosheets on Their Photocatalytic Properties

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 257 ◽  
Author(s):  
Qindan Zeng ◽  
Wei Xie ◽  
Zhihong Chen ◽  
Xin Wang ◽  
Eser Metin Akinoglu ◽  
...  
Keyword(s):  
Electric Fields ◽  
Active Sites ◽  
High Performance ◽  
Reaction System ◽  
Comprehensive Understanding ◽  
Future Design ◽  
Carrier Recombination ◽  
Surface Active ◽  
Charge Carrier Recombination ◽  
Exposed Facets

Bi24O31Br10 microcrystals composed of nanobelts and nanosheets with exposed (30-4) and (117) facets were synthesized by a simple hydrothermal method. The desired morphology and facets were obtained by adjusting the pH of the reaction system. Bi24O31Br10 nanobelts (BOB-NBs) with dominant (30-4) exposed facets were used for the photocatalytic degradation of tetracycline hydrochloride under visible light irradiation, with a degradation efficiency of up to 91% after 60 min of irradiation. The BOB-NBs possessed a higher charge separation and transfer efficiency, and showed less charge carrier recombination compared to the Bi24O31Br10 nanosheets (BOB-NSs), ascribed to a cooperative effect between the internal electric fields and surface active sites. A higher photocurrent response (2.6 times higher) was observed for BOB-NBs (12.8 μA cm−2) compared to that of BOB-NSs (4.9 μA cm−2). These findings are directional for a comprehensive understanding of the influence of the crystal facets of Bi24O31Br10 microcrystals on their photocatalytic activity and could help to guide the future design of high-performance photocatalytic materials.

scholarly journals Heterogeneous Photocatalysis and Prospects of TiO2-Based Photocatalytic DeNOxing the Atmospheric Environment

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 553 ◽  
Author(s):  
Nick Serpone
Keyword(s):  
Nitric Oxide ◽  
Metal Oxide ◽  
Nitrogen Dioxide ◽  
Active Sites ◽  
Heterogeneous Photocatalysis ◽  
Atmospheric Environment ◽  
Laboratory Setting ◽  
Noise Barriers ◽  
Surface Active ◽  
The Many

This article reviews the efforts of the last two decades to deNOxify the atmospheric environment with TiO2-based photocatalytic materials supported on various cementitious-like substrates. Prior to undertaking this important aspect of applied photocatalysis with metal-oxide emiconductor photocatalysts, however, it is pertinent to describe and understand the fundamentals of Heterogeneous Photocatalysis. The many attempts done in a laboratory setting to degrade (deNOxify) the major components that make up the NOx, namely nitric oxide (NO) and nitrogen dioxide (NO2), but most importantly the efforts expended in deNOxifying the real environment upon depositing titania-based coatings on various model and authentic infrastructures, such as urban roads, highway noise barriers, tunnels, and building external walls among others, are examined. Both laboratory and outdoor experimentations have been performed toward NOx being oxidized to form nitrates (NO3−) that remain adsorbed on the TiO2-based photocatalytic surfaces (except in tunnels—indoor walls) but get subsequently dislodged by rain or by periodic washings of the infrastructures. However, no serious considerations have been given to the possible conversion of NOx via photocatalytic reduction back to N2 and O2 gases that would restore the atmospheric environment, as the adsorbed nitrates block the surface-active sites of the photocatalyst and when washed-off ultimately cause unduly damages to the environment.

Core-shell nanostructured Zn-Co-O@CoS arrays for high-performance hybrid supercapacitors

2021 ◽  
Author(s):  
Yi He ◽  
Lei Xie ◽  
Shixiang Ding ◽  
Yujia Long ◽  
Xinyi Zhou ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Energy Storage ◽  
Active Sites ◽  
High Performance ◽  
Electronic Conductivity ◽  
Wide Distribution ◽  
Energy Storage Materials ◽  
Core Shell ◽  
Storage Materials ◽  
Hybrid Supercapacitors

Although the zinc oxide (ZnO) with wide distribution is one of the most attractive energy storage materials, the low electronic conductivity and insufficient active sites of bulk ZnO increase the...

Sign in / Sign up

Export Citation Format

Share Document