scholarly journals Photocatalytic water splitting by N-TiO2 on MgO (111) with exceptional quantum efficiencies at elevated temperatures

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yiyang Li ◽  
Yung-Kang Peng ◽  
Liangsheng Hu ◽  
Jianwei Zheng ◽  
Dharmalingam Prabhakaran ◽  
...  
Keyword(s):  
Water Splitting ◽  
Elevated Temperatures ◽  
Practical Method ◽  
Charge Carriers ◽  
Molar Ratio ◽  
Electron Hole ◽  
Photocatalytic Water Splitting ◽  
The Past ◽  
Electron Hole Pair ◽  
Electric Field Polarization

Abstract Photocatalytic water splitting is attracting enormous interest for the storage of solar energy but no practical method has yet been identified. In the past decades, various systems have been developed but most of them suffer from low activities, a narrow range of absorption and poor quantum efficiencies (Q.E.) due to fast recombination of charge carriers. Here we report a dramatic suppression of electron-hole pair recombination on the surface of N-doped TiO2 based nanocatalysts under enhanced concentrations of H+ and OH−, and local electric field polarization of a MgO (111) support during photolysis of water at elevated temperatures. Thus, a broad optical absorption is seen, producing O2 and H2 in a 1:2 molar ratio with a H2 evolution rate of over 11,000 μmol g−1 h−1 without any sacrificial reagents at 270 °C. An exceptional range of Q.E. from 81.8% at 437 nm to 3.2% at 1000 nm is also reported.

Photocatalyst with a metal-free electron–hole pair double transfer mechanism for pharmaceutical and personal care product degradation

2019 ◽  
Vol 6 (11) ◽  
pp. 3292-3306 ◽  
Author(s):  
Tiansheng Chen ◽  
Qianxin Zhang ◽  
Xiaoshan Zheng ◽  
Zhijie Xie ◽  
Yongqin Zeng ◽  
...  
Keyword(s):  
Photocatalytic Oxidation ◽  
Electron Hole ◽  
Oxidation Processes ◽  
Metal Free ◽  
Personal Care Product ◽  
The Past ◽  
Electron Hole Pair ◽  
The Subject ◽  
Low Efficiency ◽  
Product Degradation

Advanced photocatalytic oxidation processes for water purification have been the subject of extensive research over the past several years; however, the low efficiency utilization of photogenerated carriers remains a major challenge.

scholarly journals ZNO-Ag/PS and ZnO/PS Films for Photocatalytic Degradation of Methylene Blue

2020 ◽  
Vol 20 (2) ◽  
pp. 314 ◽  
Author(s):  
Hassan Khuder Naji ◽  
Amjed Mirza Oda ◽  
Wesam Abdulaljeleel ◽  
Hussein Abdilkadhim ◽  
Rawaa Hefdhi
Keyword(s):  
Methylene Blue ◽  
Catalyst Surface ◽  
Molar Ratio ◽  
Photocatalytic Reaction ◽  
Electron Hole ◽  
Xrd Pattern ◽  
Eds Analysis ◽  
Electron Hole Pair ◽  
High Roughness ◽  
Ag Catalyst

Two films of ZnO-Ag/polystyrene (ZnO-Ag/PS) and ZnO/polystyrene (ZnO/PS) have been prepared to evaluate the photodegradation ability of stabilized catalysts. The efficiency of ZnO improved against recombination of electron-hole pair by modification of catalyst surface with Ag photodeposition to be more resistant towards photocorrosion. ZnO-Ag catalyst was characterized by SEM and EDS analysis to show high roughness of this catalyst and Ag deposited on the surface was 2% (molar ratio). ZnO-Ag/PS and ZnO/PS composites were made as films and were then analyzed by FTIR spectra that showed the interaction of ZnO and ZnO-Ag with polystyrene appeared in the range of 400–620 cm–1, XRD pattern indicated the presence of Ag nanoparticles on the surface of ZnO and ZnO/PS film has maximum absorbance at 376 nm in UV-VIS spectra. This value shifted to 380 nm because of the photodeposition. The photocatalytic reaction was depicted using methylene blue (MB) in the UV-irradiation action of stacked films in MB solution. The result showed that both ZnO-Ag/PS and ZnO/PS films gave efficiency to remove MB by 97% and 70%, respectively. The reusability test of the films showed that ZnO-Ag/PS was more resistant than ZnO/PS. The presence of Ag also increased the efficiency in photodegradation and resistance against photocorrosion.

Behavior of Photogenerated Electron–Hole Pair for Water Splitting on TiO2(110)

2018 ◽  
Vol 122 (40) ◽  
pp. 22930-22938 ◽  
Author(s):  
Fan Jin ◽  
Min Wei ◽  
Tingwei Chen ◽  
Huizhong Ma ◽  
Guokui Liu ◽  
...  
Keyword(s):  
Water Splitting ◽  
Photogenerated Electron ◽  
Hole Pair ◽  
Electron Hole ◽  
Electron Hole Pair

scholarly journals Enhanced Photoelectrocatalytic Performance of TiO2 Nanorods in Photoelectrochemical Water Splitting Cell by Using an Alcoholic Sacrificial Agent

2019 ◽  
Author(s):  
Armin Hariri ◽  
Neda Gilani ◽  
Javad Vahabzadeh Pasikhani
Keyword(s):  
Water Splitting ◽  
Hydrogen Generation ◽  
Hole Pair ◽  
Tio2 Nanorods ◽  
Generation Rate ◽  
Hydrogen Atoms ◽  
Electron Hole ◽  
Anodic Chamber ◽  
Electron Hole Pair ◽  
Sacrificial Agent

Photoelectrocatalytic water splitting by using various TiO2 nanostructures is a promising approach to generate hydrogen without harmful byproducts. However, their effective performance is restricted by some drawbacks such as high rapid electron-hole pair recombination and backward reaction producing H2O. Thus in this study, the probability of enhancing hydrogen generation rate by adding methanol as a sacrificial agent to the anodic chamber of a two-compartment photoelectrochemical cell is investigated. Herein, one-dimensional elongated TiO2 nanorods that were fabricated via a facile one-pot hydrothermal method are utilized as potent photoanode. Voltammetric characterizations confirm that addition of alcoholic sacrificial agent has a significant effect on photoelectrochemical properties of TiO2 nanorods which by adding 10 wt% of methanol, the photocurrent density and photoconversion efficiency increased from 0.8mA.cm-2 to 1.5mA.cm-2 and from 0.28% to 0.45%, respectively. The results of photoelectrocatalytic water splitting indicated that the hydrogen generation rate in the presence of methanol was about 1.2 times higher than that from pure water splitting. These enhancements can be attributed to the key role of methanol. Methanol molecules not only inhibit the electron-hole pair recombination but also accelerate the hydrogen generation rate by sharing their hydrogen atoms.

scholarly journals Efficient Photoelectrochemical Water Splitting by Tailoring MoS2/CoTe Heterojunction in a Photoelectrochemical Cell

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2341
Author(s):  
Effat Sitara ◽  
Habib Nasir ◽  
Asad Mumtaz ◽  
Muhammad Fahad Ehsan ◽  
Manzar Sohail ◽  
...  
Keyword(s):  
Water Splitting ◽  
Electrochemical Impedance ◽  
Linear Sweep Voltammetry ◽  
Photocurrent Density ◽  
Photoelectrochemical Water Splitting ◽  
Photoelectrochemical Cell ◽  
Electron Hole ◽  
Pair Separation ◽  
Electron Hole Pair ◽  
Electrochemical Impedance Spectroscopic

Solar energy conversion through photoelectrochemical water splitting (PEC) is an upcoming promising technique. MoS2/CoTe heterostructures were successfully prepared and utilized for PEC studies. MoS2 and CoTe were prepared by a hydrothermal method which were then ultrasonicated with wt. % ratios of 1:3, 1:1 and 3:1 to prepare MoS2/CoTe (1:3), MoS2/CoTe (1:1) and MoS2/CoTe (3:1) heterostructure, respectively. The pure materials and heterostructures were characterized by XRD, UV–vis-DRS, SEM, XPS, PL and Raman spectroscopy. Photoelectrochemical measurements were carried out by linear sweep voltammetry and electrochemical impedance spectroscopic measurements. A maximum photocurrent density of 2.791 mA/cm2 was observed for the MoS2/CoTe (1:1) heterojunction which is about 11 times higher than the pristine MoS2. This current density was obtained at an applied bias of 0.62 V vs. Ag/AgCl (1.23 V vs. RHE) under the light intensity of 100 mW/cm2 of AM 1.5G illumination. The enhanced photocurrent density may be attributed to the efficient electron–hole pair separation. The solar to hydrogen conversion efficiency was found to be 0.84% for 1:1 MoS2/CoTe, signifying the efficient formation of the p-n junction. This study offers a novel heterojunction photocatalyst, for PEC water splitting.

scholarly journals Improving Photocatalytic Degradation Activity of Organic Pollutant by Sn4+ Doping of Anatase TiO2 Hierarchical Nanospheres with Dominant {001} Facets

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1603 ◽  
Author(s):  
Meiling Sun ◽  
Weichong Kong ◽  
Yunlong Zhao ◽  
Xiaolin Liu ◽  
Jingyue Xuan ◽  
...  
Keyword(s):  
Light Absorption ◽  
Active Sites ◽  
Organic Pollutant ◽  
Photogenerated Electron ◽  
High Energy ◽  
Charge Carriers ◽  
Photon Absorption ◽  
Hydroxyl Group ◽  
Molar Ratio ◽  
Electron Hole

Herein, high-energy {001} facets and Sn4+ doping have been demonstrated to be effective strategies to improve the surface characteristics, photon absorption, and charge transport of TiO2 hierarchical nanospheres, thereby improving their photocatalytic performance. The TiO2 hierarchical nanospheres under different reaction times were prepared by solvothermal method. The TiO2 hierarchical nanospheres (24 h) expose the largest area of {001} facets, which is conducive to increase the density of surface active sites to degrade the adsorbed methylene blue (MB), enhance light scattering ability to absorb more incident photons, and finally, improve photocatalytic activity. Furthermore, the SnxTi1−xO2 (STO) hierarchical nanospheres are fabricated by Sn4+ doping, in which the Sn4+ doping energy level and surface hydroxyl group are beneficial to broaden the light absorption range, promote the generation of charge carriers, and retard the recombination of electron–hole pairs, thereby increasing the probability of charge carriers participating in photocatalytic reactions. Compared with TiO2 hierarchical nanospheres (24 h), the STO hierarchical nanospheres with 5% nSn/nTi molar ratio exhibit a 1.84-fold improvement in photodegradation of MB arising from the enhanced light absorption ability, increased number of photogenerated electron–hole pairs, and prolonged charge carrier lifetime. In addition, the detailed mechanisms are also discussed in the present paper.

scholarly journals A rationally designed two-dimensional MoSe2/Ti2CO2 heterojunction for photocatalytic overall water splitting: simultaneously suppressing electron–hole recombination and photocorrosion

2021 ◽  
Author(s):  
Cen-Feng Fu ◽  
Xingxing Li ◽  
Jinlong Yang
Keyword(s):  
Transition Metal ◽  
Water Splitting ◽  
Rational Design ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Electron Hole ◽  
Photocatalytic Water Splitting ◽  
Overall Water Splitting ◽  
Metal Dichalcogenides ◽  
Hole Recombination

The two challenges of electron–hole recombination and photocorrosion for two-dimensional transition metal dichalcogenides in the application of photocatalytic water splitting are simultaneously suppressed by rational design of heterojunctions.

The enhanced visible light photocatalytic water-splitting activity over LaVO4/g-C3N4 with oxygen defect

2021 ◽  
Author(s):  
Xuecheng Liu ◽  
Ling Gao ◽  
Gaoxiang Qi ◽  
Jie Zhang ◽  
Biyan Liu ◽  
...  
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Oxygen Defect ◽  
Electron Hole ◽  
Heterojunction Structure ◽  
Photocatalytic Water Splitting ◽  
Visible Light Photocatalytic

A heterojunction structure LaVO4/g-C3N4 composite with oxygen-defect was successfully prepared. The characterization results exhibit that the recombination of electron-hole pairs could be inhibited by the heterojunction structure. The LaVO4/g-C3N4 composite...

scholarly journals Hydrogen evolution via noble metals based photocatalysts: A review

2021 ◽  
Vol 1 (4) ◽  
Author(s):  
Asieh Akhoondi ◽  
Ankush Sharma ◽  
Dinesh Pathak ◽  
Mohammad Yusuf ◽  
Taye B. Demissie ◽  
...  
Keyword(s):  
Noble Metals ◽  
High Efficiency ◽  
Charge Carriers ◽  
Future Trends ◽  
Electron Hole ◽  
Solar Hydrogen ◽  
Pair Separation ◽  
Electron Hole Pair ◽  
Solar Hydrogen Production ◽  
New Strategies

In recent decades, the use of photocatalysts in the evolution of hydrogen (H2) has received much attention. However, the use of the well-known titanium oxide and another photocatalyst as a base for noble metals is limited due to their major weakness in electron-hole pair separation. The use of cocatalysts can be a good way to overcome this problem and provide better performance for the evolution of hydrogen. In this review, suitable high-efficiency cocatalysts for solar hydrogen production have been thoroughly reviewed. New strategies and solutions were examined in terms of increasing the recombination of charge carriers, designing reactive sites, and enhancing the wavelengths of light absorption. Several new types of cocatalysts based on semiconductors in noble groups and dual metals have been evaluated. It is expected that these photocatalysts will be able to reduce the activation energy of reaction and charge separation. In this regard, the existing views and challenges in the field of photocatalysts are presented. The characteristics of monoatomic photocatalysts are reviewed in this manuscript and the latest advances in this field are summarized. Further, the future trends and upcoming research are also briefly discussed. Finally, this review presents noble metal-based photocatalysts for providing suitable photocatalysts on a larger scale and improving their applicability.

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