scholarly journals 4-Nitrophenol Efficient Photoreduction from Exfoliated and Protonated Phenyl-Doped Graphitic Carbon Nitride Nanosheets

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3752
Author(s):  
Stefania Porcu ◽  
Francesco Secci ◽  
Qader Abdulqader Abdullah ◽  
Pier Carlo Ricci
Keyword(s):  
Recombination Rate ◽  
Carbon Nitride ◽  
Bulk Material ◽  
Kinetic Constant ◽  
Photogenerated Electron ◽  
Optical Characterization ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
Detailed Mechanism ◽  
Carbon Nitride Nanosheets

The photoreduction of 4-nitrophenol to 4-aminophenol by means of protonated and exfoliated phenyl-doped carbon nitride is reported. Although carbon nitride-based materials have been recognized as efficient photocatalysts, the photoreduction of 4-nitrophenol to 4-aminophenol is not allowed because of the high recombination rate of the photogenerated electron–hole pairs. In this paper, we show the morphology effects on the photoactivity in phenyl-doped carbon nitride. Structural (TEM, XRD, Raman) and optical characterization (absorption, photoluminescence) of the protonated and exfoliated phenyl-doped carbon nitride (hereafter pePhCN) is reported. The increased photocatalytic efficiency, with respect to the bulk material, is underlined by the calculation of the kinetic constant of the photoreduction process (2.78 × 10−1 min−1 and 3.54 × 10−3 min−1) for pePhCN and bulk PhCN, respectively. Finally, the detailed mechanism of the photoreduction process of 4-nitrophenol to 4-aminophenol by modified phenyl carbon nitride is proposed.

NiFe-LDH@ZnO@NF composite for photo-degradation of Rhodamine B dye

MRS Advances ◽  
2019 ◽  
Vol 4 (33-34) ◽  
pp. 1887-1893
Author(s):  
Jun Wu ◽  
Yonghui Gong ◽  
Qiang Fu ◽  
Chunxu Pan
Keyword(s):  
Rhodamine B ◽  
Photocatalytic Performance ◽  
Nickel Foam ◽  
Photogenerated Electron ◽  
Chemical Compositions ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
Photo Degradation ◽  
Potential Applications ◽  
Rhodamine B Dye

ABSTRACTIn this paper, a novel NiFe-LDH@ZnO composite was prepared by using a facile two-step process upon nickel foam (NF) substrate. The morphologies and chemical compositions of the samples were characterized by SEM, EDS, XRD and XPS. Photocatalytic degradation of Rhodamine B dye was tested with the samples NiFe-LDH@ZnO@NF, ZnO@NF and NiFe-LDH under the same conditions. The experimental results revealed that the NiFe-LDH@ZnO@NF composite exhibited excellent photocatalytic performance, i.e., 1.4 and 2.5 times higher than that of pure ZnO and NiFe-LDH, respectively. The reason was that the NiFe-LDH@ZnO@NF composite provided a possibility to effectively inhibit the recombination of the photogenerated electron-hole pairs, and therefore enhanced the photocatalytic efficiency. This composite is expected to have potential applications in wastewater treatment field.

scholarly journals Enhanced photoelectrochemical performance of NiO-doped TiO2 nanotubes prepared by an impregnation–calcination method

2021 ◽  
pp. 174751982110562
Author(s):  
Xueqin Wang ◽  
Man Dai ◽  
Qihui Chen ◽  
Kai Cheng ◽  
Helong Xu ◽  
...  
Keyword(s):  
Recombination Rate ◽  
Photogenerated Electron ◽  
Photoelectrochemical Performance ◽  
Electron Hole ◽  
Lifetime Measurements ◽  
X Ray ◽  
Self Organized ◽  
Anodization Process ◽  
Calcination Method ◽  
Microscopy Images

To improve the photocatalytic activity of TiO2, a series of NiO–TiO2 nanotubes (NTbs) is prepared by impregnating TiO2 nanotubes in a solution of NiCl2·6H2O at different concentrations. Self-organized TiO2 nanotubes are prepared by a two-step anodization process. Scanning electron microscopy images show that large particle agglomerates are formed for higher precursor concentrations, and X-ray energy-dispersive spectroscopy results indicate that the atomic percentages of Ni in the NiO–TiO2 NTbs prepared with precursor concentrations of 100 and 300 mM are 1.95% and 4.23%, respectively. Electronic lifetime measurements show that the recombination rate of photogenerated electron–hole pairs is lower for NiO–TiO2 NTbs compared to that of TiO2. Specifically, the recombination rate of the sample prepared at 50 mM is the lowest, which is associated with the longest electron lifetime. Compared to unmodified TiO2 nanotubes, NiO–TiO2 NTbs exhibit improved results for the photocatalytic degradation of rhodamine B.

scholarly journals A metal-free 3C-SiC/g-C3N4 composite with enhanced visible light photocatalytic activity

RSC Advances ◽  
2017 ◽  
Vol 7 (63) ◽  
pp. 40028-40033 ◽  
Author(s):  
Hao Xu ◽  
Zhixing Gan ◽  
Weiping Zhou ◽  
Zuoming Ding ◽  
Xiaowei Zhang
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Light Absorption ◽  
Carbon Nitride ◽  
Photocatalytic Performance ◽  
Photogenerated Electron ◽  
Electron Hole ◽  
Visible Light Absorption ◽  
Metal Free ◽  
Visible Light Photocatalytic

Insufficient visible light absorption and fast recombination of the photogenerated electron–hole pairs have seriously hampered the photocatalytic performance of graphitic carbon nitride (g-C3N4) up to now.

scholarly journals Photocatalysis and Bandgap Engineering Using ZnO Nanocomposites

2015 ◽  
Vol 2015 ◽  
pp. 1-22 ◽  
Author(s):  
Muhammad Ali Johar ◽  
Rana Arslan Afzal ◽  
Abdulrahman Ali Alazba ◽  
Umair Manzoor
Keyword(s):  
Absorption Spectrum ◽  
Graphene Oxide ◽  
Composite Materials ◽  
Photogenerated Electron ◽  
Photocatalytic Efficiency ◽  
Absorption Band Edge ◽  
Bandgap Engineering ◽  
Electron Hole ◽  
Electron Hole Pair ◽  
Electronic And Structural Properties

Nanocomposites have a great potential to work as efficient, multifunctional materials for energy conversion and photoelectrochemical reactions. Nanocomposites may reveal more improved photocatalysis by implying the improvements of their electronic and structural properties than pure photocatalyst. This paper presents the recent work carried out on photoelectrochemical reactions using the composite materials of ZnO with CdS, ZnO with SnO2, ZnO with TiO2, ZnO with Ag2S, and ZnO with graphene and graphene oxide. The photocatalytic efficiency mainly depends upon the light harvesting span of a material, lifetime of photogenerated electron-hole pair, and reactive sites available in the photocatalyst. We reviewed the UV-Vis absorption spectrum of nanocomposite and photodegradation reported by the same material and how photodegradation depends upon the factors described above. Finally the improvement in the absorption band edge of nanocomposite material is discussed.

Constructing Two-Dimensional Carbonitride Carbon/Cuprous Oxide Nanoheterostructures Toward Enhanced Visible Light Photodegradation of Organic Pollutants

2020 ◽  
Vol 15 (7) ◽  
pp. 819-830
Author(s):  
Jie Zhang ◽  
Jingzhi Tian ◽  
Tao Jing ◽  
Shuo Li ◽  
Yong Ma ◽  
...  
Keyword(s):  
Methyl Orange ◽  
Visible Light ◽  
Organic Pollutants ◽  
Visible Light Irradiation ◽  
Cuprous Oxide ◽  
Recombination Rate ◽  
Photogenerated Electron ◽  
Two Dimensional ◽  
Electron Hole ◽  
Degradation Ability

Small specific surface area as well as fast recombination rate of photoelectron–hole pairs deteriorated the photocatalytic performances of carbonitride carbon (g-C3N4) in solving environmental pollution and energy crises. In this study, cuprous oxide (Cu2O) nanocubes grew on the g-C3N4 porous nanosheet to form a n–p nanoheterostructure. This unique structure of the prepared g-C3N4/Cu2O photocatalyst resulted in the photogenerated electron–hole pairs having enhanced separation rates. Under visible light irradiation, heterojunction degradation ability of methyl orange was significantly increased and its enhanced mechanism was systematically studied.

scholarly journals Photocatalytic Decomposition of N2O by Using Nanostructured Graphitic Carbon Nitride/Zinc Oxide Photocatalysts Immobilized on Foam

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 735 ◽  
Author(s):  
Kamila Kočí ◽  
Martin Reli ◽  
Ivana Troppová ◽  
Marcel Šihor ◽  
Tereza Bajcarová ◽  
...  
Keyword(s):  
Carbon Nitride ◽  
Cost Effective ◽  
Band Gap Energy ◽  
Photocatalytic Decomposition ◽  
Photocatalytic Reaction ◽  
Photocatalytic Efficiency ◽  
Ultraviolet A ◽  
Electron Hole ◽  
Gap Energy ◽  
Significant Factors

The aim of this work was to deposit cost-effective g-C3N4/ZnO nanocomposite photocatalysts (weight ratios of g-C3N4:ZnO from 0.05:1 to 3:1) as well as pure ZnO and g-C3N4 on Al2O3 foam and to study their photocatalytic efficiency for the photocatalytic decomposition of N2O, which was studied in a home-made batch photoreactor under ultraviolet A irradiation (λ = 365 nm). Based on the photocatalysis measurements, it was found that photocatalytic decomposition of N2O in the presence of all the prepared samples was significantly higher in comparison with photolysis. The photoactivity of the investigated nanocomposite photocatalysts increased in the following order: g-C3N4/ZnO (3:1) ≈ g-C3N4/ZnO (0.45:1) ≤ g-C3N4/ZnO (2:1) ZnO < g-C3N4 < g-C3N4/ZnO (0.05:1). The g-C3N4/ZnO (0.05:1) nanocomposite showed the best photocatalytic behavior and the most effective separation of photoinduced electron–hole pairs from all nanocomposites. The key roles played in photocatalytic activity were the electron–hole separation and the position and potential of the valence and conduction band. On the other hand, the specific surface area and band gap energy were not the significant factors in N2O photocatalytic decomposition. Immobilization of the photocatalyst on the foam permits facile manipulation after photocatalytic reaction and their repeated application.

Amorphous Co3S4 nanoparticle-modified tubular g-C3N4 forms step-scheme heterojunctions for photocatalytic hydrogen production

2021 ◽  
Author(s):  
Yuanpeng Wang ◽  
Xuqiang Hao ◽  
Lijun Zhang ◽  
Zhiliang Jin ◽  
Tiansheng Zhao
Keyword(s):  
Hydrogen Production ◽  
Band Structure ◽  
Recombination Rate ◽  
Photogenerated Electron ◽  
Electron Hole ◽  
Photocatalytic Hydrogen Production

An effective method to reduce the recombination rate of photogenerated electron–hole pairs was developed by the construction of heterojunctions with rationally designed photocatalysts having a matched band structure.

scholarly journals Boosting of photocatalytic hydrogen evolution via chlorine doping of polymeric carbon nitride

2021 ◽  
Vol 12 ◽  
pp. 473-484
Author(s):  
Malgorzata Aleksandrzak ◽  
Michalina Kijaczko ◽  
Wojciech Kukulka ◽  
Daria Baranowska ◽  
Martyna Baca ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Carbon Nitride ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
Bandgap Narrowing ◽  
Chlorine Doping ◽  
Photogenerated Electrons ◽  
Reducing Ability ◽  
Polymeric Carbon ◽  
Cl Atoms

Chlorine is found to be a suitable element for the modification of polymeric carbon nitride properties towards an efficient visible-light photocatalytic activity. In this study, chlorine-doped polymeric carbon nitride (Cl-PCN) has been examined as a photocatalyst in the hydrogen evolution reaction. The following aspects were found to enhance the photocatalytic efficiency of Cl-PCN: (i) unique location of Cl atoms at the interlayers of PCN instead of on its π-conjugated planes, (ii) slight bandgap narrowing, (iii) lower recombination rate of the electron–hole pairs, (iv) improved photogenerated charge transport and separation, and (v) higher reducing ability of the photogenerated electrons. The above factors affected the 4.4-fold enhancement of the photocatalytic efficiency in hydrogen evolution in comparison to the pristine catalyst.

scholarly journals Photocatalytic Properties of Zinc Oxide and Graphene Nanocomposites

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Avery Ann McLain
Keyword(s):  
Zinc Oxide ◽  
Recombination Rate ◽  
Room Temperature ◽  
Photogenerated Electron ◽  
Degradation Process ◽  
Reaction Process ◽  
Photocatalytic Properties ◽  
Blue Dye ◽  
Electron Hole ◽  
Graphene Nanocomposites

Zinc oxide (ZnO), as a semiconducting oxide, has potential as a photocatalyst due to some of the properties it possesses, including a large excitation energy, deep violet/borderline ultraviolet (UV) absorption at room temperature, and good photocatalytic activity. However, the main issue with using ZnO as a photocatalyst is that it has a rapid rate for the recombination of electron-hole pairs. Since the photoactivity of a catalyst is determined by its ability to create photogenerated electron-hole pairs, having a fast recombination rate can interfere with the reaction process. This issue could potentially be fixed by combining the ZnO with graphene, a carbon-based material. The conjugated structure of graphene enables the separation of charges in the photocatalytic process, so by combining ZnO and graphene the recombination rate could possibly be slowed while retaining the beneficial properties of both materials. This project analyzes the effects of ZnO/graphene nanocomposites on the degradation process of methylene blue dye. This dye breaks down when exposed to solar light, and so the photocatalytic properties of the nanocomposites can be studied by examining how they influence the speed of the reaction process.

scholarly journals Rationally Designed Bi2M2O9 (M = Mo/W) Photocatalysts with Significantly Enhanced Photocatalytic Activity

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7334
Author(s):  
Fangzhi Wang ◽  
Xiaoyan Zhou ◽  
Jing Li ◽  
Qiuyue He ◽  
Ling Zheng ◽  
...  
Keyword(s):  
Diffuse Reflectance ◽  
Photocatalytic Performance ◽  
Diffuse Reflectance Spectroscopy ◽  
Photogenerated Electron ◽  
Reflectance Spectroscopy ◽  
Active Species ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
Radical Trapping ◽  
Structure Morphology

Novel Bi2W2O9 and Bi2Mo2O9 with irregular polyhedron structure were successfully synthesized by a hydrothermal method. Compared to ordinary Bi2WO6 and Bi2MoO6, the modified structure of Bi2W2O9 and Bi2Mo2O9 were observed, which led to an enhancement of photocatalytic performance. To investigate the possible mechanism of enhancing photocatalytic efficiency, the crystal structure, morphology, elemental composition, and optical properties of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9 were examined. UV-Vis diffuse reflectance spectroscopy revealed the visible-light absorption ability of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9. Photoluminescence (PL) and photocurrent indicated that Bi2W2O9 and Bi2Mo2O9 pose an enhanced ability of photogenerated electron–hole pairs separation. Radical trapping experiments revealed that photogenerated holes and superoxide radicals were the main active species. It can be conjectured that the promoted photocatalytic performance related to the modified structure, and a possible mechanism was discussed in detail.

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