High specific surface CeO2-NPs doped loose porous C3N4 for enhanced photocatalytic oxidation ability

2022 ◽  
Author(s):  
Qian Gu ◽  
Pingping Jiang ◽  
Kai Zhang ◽  
Yirui Shen ◽  
Yan Leng ◽  
...  
Keyword(s):  
Specific Surface ◽  
Benzyl Alcohol ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Photocatalytic Oxidation ◽  
Separation Efficiency ◽  
Mixed Valence ◽  
Light Response ◽  
Step Method

Abstract Porous C3N4 (PCN) is favored by researchers because it has more surface active sites, higher specific surface area and stronger light absorption ability than traditional g-C3N4. In this study, cerium dioxide nanoparticles (CeO2-NPs) with mixed valence state of Ce3+ and Ce4+ were doped into the PCN framework by a two-step method. The results indicate that CeO2-NPs are highly dispersed in the PCN framework, which leads to a narrower band gap, a wider range of the light response and an improved the separation efficiency of photogenerated charge in PCN. Moreover, the specific surface area (145.69 m2•g-1) of CeO2-NPs doped PCN is a 25.5 % enhancement than that of PCN (116.13 m2•g-1). In the experiment of photocatalytic selective oxidation of benzyl alcohol, CeO2-NPs doped porous C3N4 exhibits excellent photocatalytic activity, especially Ce-PCN-30. The conversion rate of benzyl alcohol reaches 74.9 % using Ce-PCN-30 as photocatalyst by 8 hours of illumination, which is 25.7 % higher than that of pure porous C3N4. Additionally, CeO2-NPs doped porous C3N4 also exhibits better photocatalytic efficiency for other aromatic alcohols.

Preparation of Fe/N co-doped hierarchical porous carbon nanosheets derived from chitosan nanofibers for high-performance supercapacitors

2021 ◽  
pp. 1-16
Author(s):  
Yaqi Yang ◽  
Ziqiang Shao ◽  
Feijun Wang
Keyword(s):  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Double Layer ◽  
Specific Surface Area ◽  
Porous Carbon ◽  
Active Sites ◽  
Transport Pathway ◽  
Carbon Nanosheets ◽  
Hierarchical Porous

Abstract Due to the low specific capacitance and small specific surface area of conventional carbon materials used as electrode materials for double-layer capacitors, the search for more ideal materials and ingenious preparation methods remains a major challenge. In this study, fractional porous carbon nanosheets were prepared by co-doping Fe and N with chitosan as nitrogen source. The advantage of this method is that the carbon nanosheets can have a large number of pore structures and produce a large specific surface area. The presence of Fe catalyzes the graphitization of carbon in the carbon layer during carbonization process, and further increases the specific surface area of the electrode material. This structure provides an efficient ion and electron transport pathway, which enables more active sites to participate in the REDOX reaction, thus significantly enhancing the electrochemical performance of SCs. The specific surface area of CS-800 is up to 1587 m2 g−1. When the current density is 0.5 A g−1, the specific capacitance of CS-800 reaches 308.84 F g−1, and remains 84.61 % of the initial value after 10,000 cycles. The Coulomb efficiency of CS-800 is almost 100 % after a long cycle, which indicates that CS-800 has more ideal double-layer capacitance and pseudo capacitance.

Three-dimensional graphene encapsulated hollow CoSe2-SnSe2 nanoboxes for high performance asymmetric supercapacitors

2022 ◽  
Author(s):  
Kainan Li ◽  
Ke Zheng ◽  
Zhifang Zhang ◽  
Kuan Li ◽  
Ziyao Bian ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Specific Capacity ◽  
Three Dimensional ◽  
Hollow Structure ◽  
Large Specific Surface Area ◽  
Composite Aerogel

Abstract Construction of metal selenides with a large specific surface area and a hollow structure is one of the effective methods to improve the electrochemical performance of supercapacitors. However, the nano-material easily agglomerates due to the lack of support, resulting in the loss of electrochemical performance. Herein, we successfully design a three-dimensional graphene (3DG) encapsulation-protected hollow nanoboxes (CoSe2-SnSe2) composite aerogel (3DG/CoSe2-SnSe2) via a co-precipitation method coupled with self-assembly route, followed by a high temperature selenidation strategy. The obtained aerogel possesses porous 3DG conductive network, large specific surface area and plenty of reactive active sites. It could be used as a flexible and binder-free electrode after a facile mechanical compression process, which provided a high specific capacitance of 460 F g-1 at 0.5 A g-1, good rate capability of 212.7 F g-1 at 10 A g-1, and excellent cycle stability due to the fast electron/ion transfer and electrolyte diffusion. With the as-prepared 3DG/CoSe2-SnSe2 as positive electrodes and the AC (activated carbon) as negative electrodes, an asymmetric supercapacitor (3DG/CoSe2-SnSe2//AC) was fabricated, which delivered a high specific capacity of 38 F g-1 at 1A g-1 and an energy density of 11.89 W h kg-1 at 749.9 W kg-1, as well as a capacitance retention of 91.1% after 3000 cycles. This work provides a new method for preparing electrode material.

Titania nanotubes coated with graphene as a promising catalyst for the oxygen reduction reaction

2020 ◽  
Vol 44 (18) ◽  
pp. 7417-7423
Author(s):  
Jiannan Cai ◽  
Xiaofeng Zhang ◽  
Yi Zhang ◽  
Mingxing Yang ◽  
Baohua Huang ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Specific Surface ◽  
Oxygen Reduction ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Reduction Reaction ◽  
Titania Nanotubes ◽  
Electron Conductivity ◽  
Electrocatalytic Properties

The enhanced electrocatalytic properties of rGO/TiO2NTs for the ORR are a result of increased specific surface area, number of active sites and accelerated electron conductivity.

Preparation, characterization and catalytic properties of yttrium-zirconium-pillared montmorillonite and their application in supported Ce catalysts

Clay Minerals ◽  
2015 ◽  
Vol 50 (2) ◽  
pp. 211-219 ◽  
Author(s):  
Bo Xue ◽  
Hongmei Guo ◽  
Lujie Liu ◽  
Min Chen
Keyword(s):  
Catalytic Activity ◽  
Ethyl Acetate ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Industrial Applications ◽  
High Catalytic Activity ◽  
Total Oxidation ◽  
Pillared Montmorillonite

AbstractA new yttrium-zirconium-pillared montmorillonite (Y-Zr-MMT), was synthesized, characterized and used as a Ce catalyst support. The Y-Zr-MMT is a good support for dispersing cerium active sites and it is responsible for the high activity in the total oxidation of acetone, toluene and ethyl acetate. The Y-Zr-MMT shows greater advantages than the conventional alumina/cordierite honeycomb supports such as large specific surface area, lower cost and easier preparation. Catalytic tests demonstrated that Ce/Y-Zr-MMT (Ce loading 8.0%) was the most active, with the total oxidation of acetone, toluene and ethyl acetate being achieved at 220, 300 and 220°C, respectively. The catalyst displayed better activity for the oxidation of acetone and ethyl acetate than a conventional, supported Pd-catalyst under similar conditions. The special structure of the yttrium-doped zirconium-pillared montmorillonite can strengthen the interaction between the CeO2 and Zr-MMT support and improve the dispersion of the Ce particles, which enhances the catalytic activity for the oxidation of VOCs. The new catalyst, 8.0%Ce/Y-Zr-MMT, could be promising for industrial applications due to its high catalytic activity and low cost. The support and the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET specific surface area measurements.

scholarly journals Application of CoMn/CoFe layered double hydroxide based on metal-organic frameworks template to activate peroxymonosulfate for 2, 4-dichlorophenol degradation

2021 ◽  
Author(s):  
Chenyu Liu ◽  
Haitong Wei ◽  
Yanhui Gao ◽  
Ning Wang ◽  
Xiaoying Yuan ◽  
...  
Keyword(s):  
Specific Surface ◽  
Pore Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Metal Organic Frameworks ◽  
High Specific Surface Area ◽  
State Transformation ◽  
Alkaline Conditions ◽  
Metal Organic

Abstract Metal-Organic Frameworks (MOFs) have unique properties and stable structure, which have been widely used as templates/precursors to prepare well-developed pore structure and high specific surface area materials. In this article, an innovative and facile method of crystal reorganization was designed by using MOFs as sacrificial templates to prepare LDH nano-layer sheet structure through a pseudomorphic conversion process under alkaline conditions. The obtained CoMn-LDH and CoFe-LDH catalysts broke the ligand of MOFs and reorganized the structure on the basis of retaining a high specific surface area and a large number of pores, which have higher specific surface area and well-developed pore structure than LDH catalysts prepared by traditional methods, and thus provide more active sites to activate PMS. Due to the unique framework structure of MOFs, the MOF derived CoMn-LDH and CoFe-LDH catalysts could provide more active sites to activate PMS, and achieve a 2, 4-dichlorophenol (2, 4-DCP) degradation of 99.3% and 99.2% within 20 min, respectively. Besides, the two LDH catalysts displayed excellent degradation performance for bisphenol A (BPA), ciprofloxacin (CIP) and 2, 4-dichlorophenoxyacetic acid (2, 4-D). XPS indicated that the valence state transformation of metal elements participated in PMS activation. EPR manifested sulfate radical () and singlet oxygen (1O2) were the main species for degrading pollutants. In addition, after the three-cycle experiment, the CoMn-LDH and CoFe-LDH catalysts also showed long-term stability with a slight activity decrease in the third cycle. The phytotoxicity assessment determined by the germination of mung beans proved that PMS activation by MOFs-derived LDH catalyst can basically eliminate the phytotoxicity of 2, 4-D solution. This research not only developed high-activity LDH catalysts for PMS activation, but also expanded the environmental applications of MOFs derivants.

scholarly journals Continuously Improved Photocatalytic Performance of Zn2SnO4/SnO2/Cu2O Composites by Structural Modulation and Band Alignment Modification

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1390 ◽  
Author(s):  
Tiekun Jia ◽  
Junchao An ◽  
Dongsheng Yu ◽  
Jili Li ◽  
Fang Fu ◽  
...  
Keyword(s):  
Visible Light ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Photocatalytic Performance ◽  
Band Alignment ◽  
Energy Utilization ◽  
Structural Modulation ◽  
Hierarchical Architectures

Improving the photocatalytic performance of multi-component photocatalysts through structural modulation and band alignment engineering has attracted great interest in the context of solar energy utilization and conversion. In our work, Zn2SnO4/SnO2 hierarchical architectures comprising nanorod building block assemblies were first achieved via a facile solvothermal synthesis route with lysine and ethylenediamine (EDA) as directing agents, and then chemically etched in NaOH solution to enlarge the surface area and augment active sites. The etched Zn2SnO4/SnO2 hierarchical architectures were further decorated by Cu2O nanoparticles though an in situ chemical deposition method based on band alignment engineering. In comparison with unetched Zn2SnO4/SnO2, the specific surface area of Zn2SnO4/SnO2/Cu2O hierarchical architectures became larger, and the responsive region and absorbance intensity became wider and higher in the whole visible-light range. Zn2SnO4/SnO2/Cu2O hybrid photocatalysts presented enormously improved visible-light photocatalytic behaviour for Rhodamine B (RhB) decomposition. The enhancement of photocatalytic behaviour was dominantly attributed to the synergy effect of the larger specific surface area, higher light absorption capacity, and more effective photo-induced charge carrier separation and migration. A proposed mechanism for the enormously promoted photocatalytic behaviour is brought forth on the basis of the energy-band structure combined with experimental results.

scholarly journals Syngas Production via CO2 Reforming of Methane Over SrNiO3 and CeNiO3 Perovskites

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2928
Author(s):  
Naushad Ahmad ◽  
Fahad Alharthi ◽  
Manawwer Alam ◽  
Rizwan Wahab ◽  
Salim Manoharadas ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Active Sites ◽  
Catalyst Deactivation ◽  
Dry Reforming Of Methane ◽  
Volume Number ◽  
Syngas Production

The development of a transition-metal-based catalyst with concomitant high activity and stability due to its distinguishing characteristics, yielding an abundance of active sites, is considered to be the bottleneck for the dry reforming of methane (DRM). This work presents the catalytic activity and durability of SrNiO3 and CeNiO3 perovskites for syngas production via DRM. CeNiO3 exhibits a higher specific surface area, pore volume, number of reducible species, and nickel dispersion when compared to SrNiO3. The catalytic activity results demonstrate higher CH4 (54.3%) and CO2 (64.8%) conversions for CeNiO3, compared to 22% (CH4 conversion) and 34.7% (CO2 conversion) for SrNiO3. The decrease in catalytic activity after replacing cerium with strontium is attributed to a decrease in specific surface area and pore volume, and nickel active sites covered with strontium carbonate. The stability results reveal the deactivation of both the catalysts (SrNiO3 and CeNiO3) but SrNiO3 showed more deactivation than CeNiO3, as demonstrated by deactivation factors. The catalyst deactivation is mainly attributed to carbon deposition and these findings are verified by characterizing the spent catalysts.

scholarly journals The effect of iron nanocrystallites’ size in catalysts for ammonia synthesis on nitriding reaction and catalytic ammonia decomposition

2011 ◽  
Vol 9 (2) ◽  
pp. 240-244 ◽  
Author(s):  
Rafał Pelka ◽  
Karolina Kiełbasa ◽  
Walerian Arabczyk
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Atmospheric Pressure ◽  
Active Sites ◽  
Ammonia Synthesis ◽  
Iron Catalyst ◽  
Ammonia Decomposition ◽  
Mean Size ◽  
Catalytic Ammonia Decomposition

AbstractIron catalyst for ammonia synthesis of various mean sizes of iron nanocrystallites were nitrided with ammonia in a differential reactor equipped with systems that made it possible to conduct both thermogravimetric measurements and hydrogen concentration analyses in the reacting gas mixture. The nitriding process was investigated under atmospheric pressure at the temperature of 475°C. It was found that along with an increase of mean size of iron nanocrystallites, with a decrease of specific surface area of the samples, nitriding degree of solid samples increased. At the same time the rate of surface reaction of catalytic ammonia decomposition decreased. Along with an increase of the samples’ specific surface area an increase of the catalyst’s activity was observed. However, it was also observed that the concentration of active sites on the catalysts’ surface decreased along with an increase of specific surface area.

scholarly journals Textural and structural modifications of saponite from Cerro del Aguila by acid treatment

Clay Minerals ◽  
2001 ◽  
Vol 36 (4) ◽  
pp. 483-488 ◽  
Author(s):  
M. Suárez Barrios ◽  
C. de Santiago Buey ◽  
E. García Romero ◽  
J. M. Martín Pozas
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Acid Treatment ◽  
Active Sites ◽  
Internal Surface ◽  
Acid Activation ◽  
Acid Attack ◽  
Surface Areas ◽  
Treated Sample

AbstractThe physicochemical properties of clays can be modified by acid treatment with inorganic acids. This treatment is usually referred to as ‘acid activation’, because it increases the specific surface area and the number of active sites of the solids. In the present study, the acid activation of saponite from Cerro del Aguila (Madrid, Spain) with HCl solutions was measured. Illite, quartz and small amounts of feldspar were found as impurities in the raw saponite.Acid treatments were carried out with different concentrations of HCl solutions. The samples obtained were characterized by mineralogical and chemical analyses, XRD, FT-IR spectroscopy, N2 adsorption-desorption isotherms and TEM. The acid attack, under the conditions employed, produced a progressive destruction of the structure of saponite by partial dissolution of the octahedral Mg(II) cations. Amorphous silica coming from the tetrahedral sheet of saponite was generated. The specific surface area of the most intensely treated sample (2.5% for 24 h) was doubled with respect to that of natural saponite. This increase in the surface area is due to the increase in both the external and internal surface areas.

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