Figure 6 - uploaded by Shiyun Ai
Content may be subject to copyright.
Photodegradation of MO by different photocatalysts under visible-light irradiation (l ! 400 nm). A) UV/Vis spectra of MO solutions after adsorption. B) UV/Vis spectra of MO solutions after release of MO molecules by adding a 1.5 mol L À1 solution of NaNO 3 in ethanol/water A C H T U N G T R E N N U N G (1/1 v/v). C) UV/Vis spectra of MO solutions after irradiation for different times and then release of MO molecules.
Source publication
A facile anion-exchange precipitation method was used to synthesize bifunctional Ag/AgBr/Co-Ni-NO(3) layered double hydroxide (LDH) nanocomposites by adding AgNO(3) solution to a suspension of Co-Ni-Br LDH. The Ag/AgBr nanoparticles were highly dispersed on the sheets of Co-Ni-NO(3) LDH. The prepared nanocomposites were used to adsorb and photocata...
Contexts in source publication
Context 1
... by this method, it can be determined whether the adsorbed MO molecules in the LDH could be photodegraded during irra- diation. The bottom curve in Figure 6 shows the UV/Vis data of MO solution after adsorption by Ag/AgBr/Co-Ni- NO 3 , irradiation, and then addition of NaNO 3 solution. After adsorption for 20 min, almost all MO molecules were adsorbed. ...
Context 2
... shown in Figure 6, both Co-Ni-Br and Ag/AgBr show photocatalytic activity toward MO, but Ag/AgBr/Co-Ni- NO 3 displays the highest photocatalytic activity and de- grades almost all MO dye molecules in 120 min, while Ag/ AgBr and Co-Ni-Br repectively resulted in about 63 and 15 % degradation under visible-light irradiation for 120 min at an MO concentration of 25 mg L À1 . Thus, immobilizing Ag/AgBr nanoparticles on Co-Ni-NO 3 sheets greatly en- hanced the photocatalytic activity. ...
Context 3
... The above method can be used to prepare other LDH/Ag salt composites, such as AgCl/Co(OH) 2 , AgCl/Zn-Cr LDH, and Ag 2 WO 4 /Ni-Cr LDH. The XRD patterns (see Support- ing Information, Figures S4-S6) of the composites were www.chemeurj.org characterized, and preliminary results indicate that these composites were successfully prepared by this method, that is the method described herein is a general strategy to pre- pare LDH/silver salt composites. ...
Similar publications
AbstractA facile anion‐exchange precipitation method was used to synthesize bifunctional Ag/AgBr/Co–Ni–NO3 layered double hydroxide (LDH) nanocomposites by adding AgNO3 solution to a suspension of Co–Ni–Br LDH. The Ag/AgBr nanoparticles were highly dispersed on the sheets of Co–Ni–NO3 LDH. The prepared nanocomposites were used to adsorb and photoca...
Citations
... By osmotic swelling of the host material in the presence of a polar organic solvent for example formamide, the exfoliation of LDH can be accomplished, resulting in a colloidal suspension of negatively-charged LDH nanosheets. Various LDH nanosheets with significant compositional changes of M 2+ /M 3+ or M 4+ metal ions were described thus far, including binary Zn-Cr/Al/Ti/Fe-LDH [219][220][221][222][223][224][225], Co-Al/Fe/Ni-LDH [226][227][228], Table 1 Various g-C 3 N 4 hybrids for solar energy harvesting. ...
In recent years, the process of photocatalytic degradation is considered as one of the outstanding strategies for removing pollutants from aqueous solutions than traditional adsorption. The wide-ranging band structures, sufficient active sites, and significant specific surface area of 2D materials offer them a significant amount of potential as an effective photocatalyst in the degradation of contaminants. This potential is especially evident in hybridization with other functional components such as metal oxides, sulfides, carbon nitrides, and graphene, amongst others. In this article, among the many available strategies, the one-of-a-kind hybridization of 2D materials with a large number of functional species is examined in great detail, with a focus on the enhanced photocatalytic performances and remarkable activity that is friendly to the environment that it enables for water desalination. Current developments in 2D hybrid photocatalysts for environmental remediation are discussed in this feature review article. The current review will inspire the reader to have a better understanding of the feasible optimization of 2D hybrid photocatalysts for solar energy harvesting, and at the end, the authors' recommendations aligned with future challenges and opportunities will set the path for readers. In addition, several different hybridization approaches are investigated.
... The incremental increase in global fuel conflict as a result of exhaustible energy resources, as well as unfavorable ecological situations owing to rapid urbanization and industrialization, has become a key obstacle in current era [1e10]. The semiconductors based artificial photosynthesis has been regarded as one of the most prestigious techniques in order to fix the global fuel crisis by gathering, transforming and storing sustainable energy for the generation of practicable energy in a wide range of ecological systems [11,12]. Although the visionary research in 1972, was firstly initiated by Fujishima and Honda regarding the splitting of water into oxygen (O 2 ) and hydrogen (H 2 ) as a byproduct onto the substrate of TiO 2 anode and Pt cathode based electrodes through UV light ( Fig. 1a) [13]. ...
Recently, the graphite based heterogeneous photocatalysts has attained tremendous research attention in various environmental applications. Among them, the graphitic carbon nitride (g-C3N4) is categorized as a unique solar active particle with its outstanding intrinsic properties i.e., adequate band configuration, excellent light absorptivity and thermo-physical durability, which make it highly useful and reliable for revenue transformation and ecological concerns. Considering the intrinsic potential of g-C3N4 in photocatalysis, so far, no report has been done in literature for its extraordinary configuration, morphological characteristics and perspective tuning for said applications. To overcome this research gap, our primary emphasis of this review regarding photocatalysis is to provide layout as well as the advancement of visible-light-fueled materials as highly stabilized and extremely effective ones for pragmatic implementation. Thus, this existing comprehensive assessment conducts a systematic survey over visible light driven non-metal novel g-C3N4. The major advancement of this evaluation is the fabrication of well-designed nanosized g-C3N4 photocatalysts with unique configurable frameworks and compositions. Furthermore, alternative techniques in order to customize the analogue band configuration and noticeable cultivation such as metal (cation), nonmetal (anion) doping, worthy metal activating, and alloy initiation with certain semiconductors are discussed in detail. In addition to this, g-C3N4 photocatalytic functionalities towards photocatalytic hydrogen evolution, CO2 photoreduction, biological metal ions deterioration as well as bacterial sanitization are also presented and discussed in detail. Therefore, we believe that such a pivotal compact assessment can provide a roadmap in several perspectives on the currently underway obstacles in the innovation of effective g-C3N4 catalytic design processes. Moreover, this critical assessment will ultimately serve as a useful supplement in the research area of g-C3N4 nanosized photocatalysts and for the researchers working on its key aspects in diverse range of natural, chemistry, engineering and environmental applications.
... And there usually have some difficulty to be separated for reuse them. In our previous work, we have prepared several kinds of photocatalytic nanomaterials, 1 3 such as Cu/g-C 3 N 4 based photocatalysts [21], layered double hydroxides based composites [22], Sn doped ZnO microspheres [23] and porous carbon-CeO 2 composites [24]. These photocatalysts showed enhanced photocatalytic activities. ...
Photocatalytic nanomaterials have been widely used in the photocatalytic fields. However, traditional nanomaterials need to be dispersed in the solution and usually have some difficulties to be separated. Herein, a floating and stable g-C3N4/PMMA/CFs porous film was designed by a simple casting method. Chemically protonated g-C3N4 treated by H2SO4 has good dispersion and adhesion with PMMA. Cotton fiber solution (CFs) was added to improve the flexibility of the film. The g-C3N4/PMMA/CFs porous film provides an automatic photocatalytic reaction platform, which can float on the surface of water and absorb the sunlight easily. Furthermore, PMMA is transparent, which have negligible influence on the light absorption for g-C3N4. The photocatalytic activity of the g-C3N4/PMMA porous film showed that the film containing 6% of g-C3N4 can degrade 83% of 50 mL RhB solution (10 mg/L) in 180 min. The recyclability showed that about 97% of the photocatalytic activity can be retained after six times of reuse. The stability of the film showed that more than 90% of the photocatalytic activity can be retained after ultrasonication for 60 min.
... LDHs have a general formula [M(II)1−xM(III)x(OH)2](A n− )x/n·H2O, where M(II) (M = Mg, Zn, Cu, Ni, Co, etc.) and M(III) (M = Al, Ga, Cr, Mn, In, Fe, etc) are divalent and trivalent metals; x is the molar fraction of the trivalent metal (mol M(III)/(mol M(III) + mol(M(II)), which ranges between 0.2 and 0.4 and determines the charge density of the lamellae, while A n− is the counter anion located in the interlayer gallery [21]. In this context, the preparation of composites constituted by layered double hydroxides and silver/silver halides (Ag/AgX, X = Br, Cl, I) has been explored by Fan et al. [22]. In their study, Co-Ni LDH intercalated with bromide was treated with silver nitrate to precipitate silver bromide and then partially reduced to form the system Ag/AgBr. ...
Surface-modified ZnAl layered double hydroxides (LDHs) were prepared by reaction of AgNO3, with both ZnAlCl (LDH1) and ZnAlCO3 exchanged on the surface with chloride anions (LDH3). In this way, AgCl nanoparticles with crystalline domains ranging from 40 to 100 nm were grown on the LDH surface. An additional sample was prepared by partial reduction of silver to obtain Ag@AgCl-LDH (LDH2). The composites were tested as catalysts in Rhodamine B (RhB) degradation, wherein LDH2 showed complete cleavage of RhB after 45 min of irradiation versus 70 min needed in the presence of AgCl. This time decreased to 35 min for LDH1 and 15 min for LDH3, underlining the role of the AgCl dimensions and anion in the interlayer region. Studies on the reactive species involved in the degradation process revealed that, for all catalysts, O2·− was the main active species, while, to some extent, holes contribute to the activity of the LDH3. Finally, the composites showed high bactericidal activity, under irradiation, against Escherichia coli, comparable with that of Gentamicin, the positive control. A synergic effect of silver released from the composites and the production of reactive oxygen species was considered.
... Meanwhile, the photo-induced holes left in the valence band of CdO diffuse effectively to the surface of the catalyst and reacts with water to form OH * radicals. The O 2 * and OH * radicals are the reactive species that degrade the dye molecules with the release of CO 2 and H 2 O [35]. The chemical reactions involved in the photocatalytic mechanism of the CdO:Ag catalysts could be summarized as follows [36]: ...
The photodegradation quality of Ag-doped CdO (CdO:Ag) thin films deposited using perfume atomizer has been reported in this paper. Ag concentration in CdO is varied as 0, 1, 2 and 3 wt%, respectively. XRD studies reveal cubic crystal structure for all the CdO:Ag thin films ruling out the presence of any secondary phases and decreased crystallite size was observed with Ag doping. CdO:Ag films surfaces are composed of cauliflower shaped grains and EDX spectra ascertains that Ag has been successfully incorporated into the CdO lattice. Optical band gap tends to increase with increase in Ag concentration. Electrical resistivity showed a decreasing trend with increase in Ag concentration. Photocatalytic tests against metanil yellow confirmed that the Ag-doped CdO films exhibit better degradation efficiency than the undoped film and an efficiency of 84.44% was realized for the 2 wt% Ag-doped CdO catalyst. The recycle tests confirmed the reusable nature of the CdO:Ag catalysts.
... Comparing the R 2 value, the pseudo-second-order kinetic fit showed well agreement with experimental results. The fast adsorption velocity was probably attributed to the better affinity between NiCo-LDHs and TC molecules [44,45] . The kinetics of adsorption can be described as follows: ...
In this work, a 3D-Ag/NiCo-LDHs photocatalyst was successfully prepared. Varies analytical techniques demonstrated that the Ag/NiCo-LDHs showed excellent photocatalytic activity than pure NiCo-LDHs, which may attribute the special structure of NiCo-LDHs with adsorption performance and surface plasma resonance effect (SPR) of Ag nanoparticles. Such flower-like structure of NiCo-LDHs, the petals staggered to form a plurality of independent reaction spaces to provide more reaction space and avoid the interaction between the reaction products. Meanwhile, combining the carbon quantum dots with the SPR of Ag nanoparticles can further enhance the photocatalytic activity. Based on the analysis, the possible photocatalytic mechanism was presented.
... Here, through hydroperoxyl anion coordinated In 3 + cations as a precursor, a new layered indium hydroxide was synthesized, where only a three-dimensional cubic phase had existed before. The layer of the product exhibits an unusual structure where In(OH) 6 octahedra share edges and vertexes with each other to form layers, which is completely different from the common edge-sharing brucite-like metal-hydroxyl layers. By investigating the formation mechanism, the new layered structure is found to be formed by changing the traditional crystallization path through the hydroperoxyl anion coordinated intermediates. ...
... LMHs and their ultrathin forms have been studied extensively in many fields such as catalysis, magnetism, energy storage, and conversion due to the flexible tunability of the metal ions. [1][2][3][4][5][6][7][8][9][10] However, both LSHs and LDHs have only one structure type reported up to now, that is, brucite or brucite-like metal-hydroxyl layers, composed of edge shared M(OH) 6 octahedra. [11] The structure of the material has a great influence on the properties; the range of LMHs and their applications can be expanded if layers with a new structure type can be synthesized. ...
... The layers of layered In(OH) 3 stacked by hydrogen bonding; the interlayer distance is about 5 . However, the traditional single metal hydroxides M(OH) 2 , such as Mg(OH) 2 , b-Ni(OH) 2 , and b-Co(OH) 2 , [11] are always in the brucite structure; all M(OH) 6 octahedra share edges with their neighbors to produce 2D charge-neutral layers as shown in Figure 4 b ( Figure S5). Brucite-like Al(OH) 3 is slightly different, since only 2/3 metal sites are occupied compared with brucites, and its formula could also be written as Al 2/3 (OH) 2 ( Figure S6). ...
All reported layered metal hydroxides have brucite‐like metal‐hydroxyl host layers and the discovery of other types of layered metal hydroxides can significantly extend the layered metal hydroxide families, which is meaningful in both theory and applications. Here through hydroperoxyl anion coordinated In3+ cations as a precursor, we synthesized layered indium hydroxide which only existed as a three‐dimensional cubic phase before. The layer of the product exhibits an unusual structure where In(OH)6 octahedra share edges and vertexes with each other to form layers, which is completely different from the common edges sharing brucite‐like metal‐hydroxyl layer. By investigating the formation mechanism, the new layered structure is found to be formed by changing the traditional crystallization path through the hydroperoxyl anion coordinated intermediates. Many other new phases could also be discovered by following the same intrinsic principle.
... With the substrates as dispersing templates, homogeneous and uniform semiconductor crystal morphology could be formed, which in turn can enhance their photocatalytic performance [327][328][329][330][331][332][333][334]. The graphene sheets with high optical transmittance, large 2D specific surface area, unique electronic properties and locally conjugated aromatic system has regarded as one kind of ideal substrate candidates for photocatalytic deposition. ...
The silver halides and their corresponding composites would constitute remarkable photocatalytic systems not only in energy production but also in environmental remediation. The major advantage in these silver halides system is that plasma metal Ag⁰ species would be spontaneously generated by silver halides under light irradiation, which play dual roles of expanding light absorption range and charge carriers separation. In this tutorial review, the origin and development of silver halides, synthesis methods, construction of composite structures with other materials, photocatalytic applications, and various and controversial mechanisms are all exhaustively described.
Graphical abstractThe silver halides and their corresponding composites would constitute remarkable photocatalytic systems not only in energy production but also in environmental remediation.
... Besides, in all spectra, the existence of other bands at wavenumbers below 1000 cm −1 can be explained by the transitional mode vibrations of metal-O and metal-O-metal [27]. As shown in Fig. 2A (a), for the LDH-NO 3 , an absorption band is observed at 1384 cm −1 , which is caused by the fact that nitrate anions are present in the structure [55]. As represented in Fig. 2A (b), concerning AR-27/LDH, almost no absorption band of NO 3 − anion can be seen. ...
... Such anion-exchangeable ability enables the LDHs to be widely applied in anion adsorption materials with large adsorption capacity [22]. For example, in our previous research [23], Br intercalated Co-Ni LDHs nanosheets showed adsorption capacity of 195 mg g À 1 for methyl orange, much higher than that of commercial activated carbon (20-80 mesh) with 140 mg g À 1 . The intercalated anions can be further exchanged out of the interlayer of LDHs, which can react with metal ions to form products with different colors [24,25]. ...
In this work, a novel approach for facile and rapid detection of heavy metal ions using anion-intercalated layered double hydroxides (LDHs) modified test strips is demonstrated. By intercalating Fe(CN)64- or S2- anions into the interlayers of LDHs on the filter paper, various heavy metal ions can be easily detected based on the color change before and after reaction between the anions and the heavy metal ions. Upon the dropping of heavy metal ions solutions to the test strips, the colors of the test strips changed instantly, which can be easily observed by naked eyes. With the decrease of the concentration, the color depth changed obviously. The lowest detection concentration can be up to 1×10-6 mol L-1. Due to the easily intercalation of anions into the interlayer of the LDHs on test trips, this procedure provides a general method for the construction of LDHs modified test strips for detection of heavy metal ions. The stability of the prepared test strips is investigated. Furthermore, all the results were highly reproducible. The test strips may have potential applications in environmental monitoring fields.
