scholarly journals Photocatalytic Reduction of Cr (VI) over g-C3N4 Photocatalysts Synthesized by Different Precursors

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 7054
Author(s):  
Juan Liang ◽  
Chengjun Jing ◽  
Jiarong Wang ◽  
Yupawang Men
Keyword(s):  
Surface Area ◽  
Carbon Nitride ◽  
Hydrogen Adsorption ◽  
Direct Reduction ◽  
Reduction Process ◽  
Photocatalytic Reduction ◽  
Pyrolysis Process ◽  
Photogenerated Electrons ◽  
One Step ◽  
Amine Groups

Graphitic carbon nitride (g-C3N4) photocatalysts were synthesized via a one-step pyrolysis process using melamine, dicyandiamide, thiourea, and urea as precursors. The obtained g-C3N4 materials exhibited a significantly different performance for the photocatalytic reduction of Cr(VI) under white light irradiation, which is attributed to the altered structure and occupancies surface groups. The urea-derived g-C3N4 with nanosheet morphology, large specific surface area, and high occupancies of surface amine groups exhibited superior photocatalytic activity. The nanosheet morphology and large surface area facilitated the separation and transmission of charge, while the high occupancies of surface amine groups promoted the formation of hydrogen adsorption atomic centers which were beneficial to Cr(VI) reduction. Moreover, the possible reduction pathway of Cr(VI) to Cr(III) over the urea-derived g-C3N4 was proposed and the reduction process was mainly initiated by a direct reduction of photogenerated electrons.

scholarly journals Anatase TiO2-Decorated Graphitic Carbon Nitride for Photocatalytic Conversion of Carbon Dioxide

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 146 ◽  
Author(s):  
I-Hsiang Tseng ◽  
Yu-Min Sung ◽  
Po-Ya Chang ◽  
Chin-Yi Chen
Keyword(s):  
Surface Area ◽  
Carbon Nitride ◽  
Anatase Tio2 ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Hydroxyl Groups ◽  
Light Activity ◽  
Amine Groups ◽  
Porous Morphology

Three types of graphitic carbon nitride (gCN) nanosheets were derived from direct thermal condensation of urea, melamine, and dicyandiamide, respectively. As the sample (uCN) synthesized from urea exhibited porous morphology and highest surface area among other gCN, anatase TiO2 nanoparticles were then in-situ deposited on uCN via solvothermal process without further calcination. The resultant Ti/uCN_x samples remained with higher surface area and exhibited visible-light activity. The derived band structure of each sample also confirmed its ability to photoreduce CO2. XPS results revealed surface compositions of each sample. Those functional groups governed adsorption of reactant, interfacial interaction, electron transfer rate, and consequently influenced the yield of products. Carbon monoxide and methanol were detected from LED-lamp illuminated samples under appropriate moisture content. Samples with higher ratio of terminal amine groups produced more CO. The presence of hydroxyl groups promoted the initial conversion of methanol. The obtained Ti/uCN_0.5 and Ti/uCN_1.5 samples exhibited better quantum efficiency toward CO2 conversion and demonstrated stability to consistently produce CO under cycling photoreaction.

scholarly journals Determination of surface amine groups on amorphous carbon nitride thin films using a one step covalent grafting of a redox probe

2014 ◽  
Vol 136 ◽  
pp. 473-482 ◽  
Author(s):  
S. Jribi ◽  
S.I. Cordoba de Torresi ◽  
T. Augusto ◽  
H. Cachet ◽  
C. Debiemme-Chouvy ◽  
...  
Keyword(s):  
Thin Films ◽  
Amorphous Carbon ◽  
Carbon Nitride ◽  
Redox Probe ◽  
Covalent Grafting ◽  
One Step ◽  
Amine Groups ◽  
Amorphous Carbon Nitride

Template free synthesis of graphitic carbon nitride/titania mesoflowers

RSC Advances ◽  
2015 ◽  
Vol 5 (89) ◽  
pp. 72683-72690 ◽  
Author(s):  
Reny Thankam Thomas ◽  
N. Sandhyarani
Keyword(s):  
Surface Area ◽  
Environmental Remediation ◽  
Carbon Nitride ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Solvothermal Process ◽  
One Step ◽  
Template Free

Multifunctional solar active graphitic carbon nitride–titania mesoflowers with surface area of 147 m2 g−1 are synthesized by a one-step solvothermal process for environmental remediation.

A one-step deep eutectic solvent assisted synthesis of carbon nitride/metal oxide composites for photocatalytic nitrogen fixation

2019 ◽  
Vol 7 (10) ◽  
pp. 5719-5725 ◽  
Author(s):  
Hongyu Mou ◽  
Jinfang Wang ◽  
Deliang Zhang ◽  
Dongkun Yu ◽  
Wenjun Chen ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Metal Oxide ◽  
Carbon Nitride ◽  
Deep Eutectic Solvent ◽  
Photocatalytic Reduction ◽  
Atmospheric Environment ◽  
One Step ◽  
Oxide Composites

Preparation of g-C3N4/metal oxide composites by a general deep eutectic solvent aided method for photocatalytic reduction of nitrogen at atmospheric environment.

scholarly journals The one-step pyrolysis process of rattan-based silicon carbide multiphase ceramics prepared by sol–gel method

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Shijie Li ◽  
Heshuai Cui ◽  
Qianli Ma ◽  
Xing’e Liu ◽  
Youhong Wang ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Pyrolysis Process ◽  
Gel Method ◽  
X Ray ◽  
One Step ◽  
The One

AbstractThe sol–gel method was used to prepare rattan-based silicon carbide (R–SiC) composite ceramics under different pyrolysis parameters through adjustment of the temperature and retention time of the one-step pyrolysis process. The crystalline phases, microscopic morphology, element distribution and specific surface area of the silicon carbide (SiC) were characterized by X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), X-ray fluorescence spectrometer (XRF), field-emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and N2 physisorption. The results showed that the R–SiC prepared at different pyrolysis parameters was able to retain the porous structure of pristine rattan stem. The R–SiC prepared at 1500 ℃ for 120 min possessed the lowest density (0.25 g/cm3), the largest specific surface area (43.38 m2/g) and the highest SiC yield (44.24%). The SiC whisker was the major SiC morphology on the cross section of the R–SiC. Furthermore, the pyrolysis parameters were optimized with the SiC preparation process reaction mechanism, and material transformation methods were also discussed. This one-step pyrolysis process simplified the preparation of biogenic SiC ceramics and thus provided a potential route for the value-added utilization of rattan.

An overview of the reaction conditions for an efficient photoconversion of CO2

2018 ◽  
Vol 34 (3) ◽  
pp. 409-425 ◽  
Author(s):  
Syeda Shaima Meryem ◽  
Sadia Nasreen ◽  
Maria Siddique ◽  
Romana Khan
Keyword(s):  
Reduction Process ◽  
Product Distribution ◽  
Active Species ◽  
Photocatalytic Reduction ◽  
Key Factors ◽  
Reaction Conditions ◽  
Radical Chain ◽  
Chain Reactions ◽  
Co Catalysts ◽  
Photogenerated Electrons

Abstract Carbon dioxide (CO2) emission is one of the well-known causes of global warming. Photoconversion of CO2 to useful chemical compounds using solar energy is an attractive approach as it reduces the major greenhouse gas and promises a sustainable energy source. This method involves radical-chain reactions that form cation and anion radicals generated as a result of the reaction with photogenerated electrons (e−) and holes (h+) between metal oxide photocatalyst and the reactants. Therefore, the product distribution of a modified photocatalyst even under specific reaction conditions is difficult to predict. The CO2 photocatalytic reduction process is controlled by several conditions such as reactor configuration, photocatalyst type, and nature of the reducing agents. Here, we review the parameters such as temperature, pH, CO2 pressure, type of reductant, role of co-catalysts, dopants, and type of photocatalysts that influence the end products of the photocatalytic reduction of CO2. In this review, the different modifications recommended for the photocatalysts to improve CO2 reduction and receive maximum valuable end product (methane, ethanol, methanol, hydrogen, and carbon monoxide) have been listed. The discussion also includes specific behaviors of photocatalysts which lead to different product distribution. It has been noted that different metal and nonmetal dopants improve the activity of a photocatalyst and influence the end product distribution by altering the active species. Similarly, the key factors, i.e. size, morphology and doping, which have been ruling the photocatalytic activity of CO2 reduction under UV or visible light irradiation have been identified.

scholarly journals Post-illumination activity of Bi2WO6 in the dark from the photocatalytic “memory” effect

2021 ◽  
Vol 10 (2) ◽  
pp. 355-367
Author(s):  
Weiyi Yang ◽  
Yan Chen ◽  
Shuang Gao ◽  
Licheng Sang ◽  
Ruoge Tao ◽  
...  
Keyword(s):  
Memory Effect ◽  
Reduction Process ◽  
Production Performance ◽  
Intrinsic Activity ◽  
Light Illumination ◽  
Two Phase ◽  
Photogenerated Electrons ◽  
Composite Photocatalysts ◽  
Pure Phase ◽  
Activity Loss

AbstractPhotocatalysts with the photocatalytic “memory” effect could resolve the intrinsic activity loss of traditional photocatalysts when the light illumination is turned off. Due to the dual requirements of light absorption and energy storage/release functions, most previously reported photocatalysts with the photocatalytic “memory” effect were composite photocatalysts of two phase components, which may lose their performance due to gradually deteriorated interface conditions during their applications. In this work, a simple solvothermal process was developed to synthesize Bi2WO6 microspheres constructed by aggregated nanoflakes. The pure phase Bi2WO6 was found to possess the photocatalytic “memory” effect through the trapping and release of photogenerated electrons by the reversible chemical state change of W component in the (WO4)2− layers. When the illumination was switched off, Bi2WO6 microspheres continuously produced H2O2 in the dark as those trapped photogenerated electrons were gradually released to react with O2 through the two-electron O2 reduction process, resulting in the continuous disinfection of Escherichia coli bacteria in the dark through the photocatalytic “memory” effect. No deterioration of their cycling H2O2 production performance in the dark was observed, which verified their stable photocatalytic “memory” effect.

Metallographic Estimation of the Number of Forming Metallic Particles Obtained during Direct and Indirect Reduction of Metals from Complex Oxides

2019 ◽  
Vol 946 ◽  
pp. 523-527
Author(s):  
Arman S. Bilgenov ◽  
P.A. Gamov ◽  
V.E. Roshchin
Keyword(s):  
Metal Forming ◽  
Solid Phase ◽  
Quantitative Estimation ◽  
Direct Reduction ◽  
Reduction Process ◽  
Complex Oxide ◽  
Experimental Results ◽  
Solid Carbon ◽  
Indirect Reduction ◽  
Co Gas

The direct reduction of metals from a complex oxide with low iron content by solid carbon and indirect reduction by CO gas were studied in a vertical laboratory resistance furnace at 1300 °C for an hour reduction time. The experimental results were described from the point of view of the electrochemical nature of the metal reduction process, that involves the interaction of ions and electrons in the oxide lattice. The technique was developed by using the two different software programs for the quantitative estimation of the areas, average size and number of the metal forming in a complex oxide with extensive fields of vision. The obtained results of the quantitative characteristics of the metal forming during solid-phase carbo-thermal reduction were presented. The processes of reduction by solid carbon and CO gas based on the areas occupied by metal particles were quantitatively compared. The experimental results and the prospects for further experimental work were assessed and outlined.

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