Rapid Microwave‐Assisted Nonaqueous Synthesis and Growth Mechanism of AgCl/Ag, and Its Daylight‐Driven Plasmonic Photocatalysis

Green Ag/AgCl as an Effective Plasmonic Photocatalyst for Degradation and Mineralization of Methylthioninium Chloride

A green synthesis of Ag/AgCl with an exceptional SPR and photocatalysis property is greatly benefit to the environmental application especially pollutant removal. In this work, a novel green plasmonic photocatalysis of Ag/AgCl nanocatalyst using aqueous garlic extract (Allium Sativum L.) was successfully synthesized. The allicin and organosulfur compounds in the garlic can act as reducing agents in the green synthesis process. The nanocatalyst properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffractometer. The light-harvesting property was investigated by UV-vis absorption spectra which reveals its visible light absorption capability owing surface plasmon resonance behavior of Ag nanoparticles. The degradation and mineralization of methylthioninium chloride (MC) using this photocatalyst were evaluated under visible light and natural solar irradiation. Surface plasmon resonance of Ag nanoparticles and the presence of organosulfur from the garlic extract facilitated adsorption of MC onto the particle surface, promoting greater degradation. The photocatalytic reaction under visible light can be explained by the pseudo first-order pattern with the highest reaction rate of 0.5829 mg L−1 min−1 at pH 10. The photocatalytic activity of the Ag/AgCl under the natural sunlight reached 90% and 75% for MC and total organic carbon (TOC), respectively. The intermediate products detected during MC degradation under sunlight irradiation before final transformation to CO2, H2O, HNO3, and H2SO4 were also reported. The simplicity of Ag/AgCl green synthesis with the photocatalysis properties under visible light and sunlight can offer the convenience of applying these nanoparticles for pollutant removal in water treatment processes.

Template-assisted synthesis of Ag/AgCl hollow microcubes and their composition-dependent photocatalytic activity for the degradation of phenol

Plasmonic photocatalysts with hollow structures and tunable composition exhibit significant advantages due to their high efficiency in light collection and effective charge transfer across the tight contact heterojunction interface. Herein, hollow Ag/AgCl microcubes were developed by treating nanosheet-assembled hollow Ag microcubes with FeCl3, where a part of Ag at the interface could be in situ transformed and oxidized into AgCl. Equally, by adjusting the concentration of Fe3+ ions, Ag/AgCl hollow microcubes with different compositions could be easily achieved. Electron transfer was favored by a lot of tiny Ag/AgCl heterojunctions induced by the in situ oxidation of the multicrystalline Ag hollow microcube template containing a number of grain boundaries. The designed hollow Ag/AgCl microcubes exhibited strong visible-light adsorption owing to the surface plasmon resonance effect of Ag nanoparticles, in addition to the multiple light-reflections inside the hollow structure. The as-obtained products were then used as visible-light photocatalysts, where the results indicated that 91.6% of phenol was degraded within 150 min under visible light by the as-obtained sample with a Ag to AgCl ratio of 1 : 3. The superior visible-light photocatalytic activity resulted from the enhancement of the visible light-harvesting and the efficient charge separation at the Ag and AgCl contact interfaces.

Ag/AgCl nanoparticles embedded in porous TiO2: defect formation triggered by light irradiation

The photocatalytic activity of Ag/AgCl embedded in defective porous TiO₂ was dependent on the changes of Ti³⁺ and the formation of AgCl crystals.

Solar photocatalytic degradation of thidiazuron in Yangtze River water matrix by Ag/AgCl-AC at circumneutral condition

It is well-known that the degradation of pollutants in real water environment is not only challenging but also has practical value. This paper focuses on the photocatalytic degradation of thidiazuron (TDZ), a popular defoliant, using Ag/AgCl-AC (Ag@AC 2:1); AC stands for activated carbon) in a matrix of Yangtze River water under sunlight irradiation. The prepared composite catalyst exhibits excellent performance in TDZ degradation under near neutral condition, the degradation rate reaches 94% in 200 min under solar irradiation. The common inorganic anions (SO₄^2-, Cl^-, and HCO₃^-) and cations (Ca²⁺, Cu²⁺, and Mg²⁺) show inhibitory effect of different degrees on TDZ degradation. Humic substances such as humic acid and fulvic acid also have an effect on the photocatalytic degradation of TDZ. With the increase of humic acid concentration, there is enhancement of inhibitory effect. As for fulvic acid, its effect is complex due to competitive adsorption and photoinduction action. The degradation products as identified by UHPLC-MS are mainly CO₂, SO₂, and H₂O, indicating that the degradation was thorough. The reusability test of four runs reveals that the performance of the photocatalytic system is stable. The results demonstrate that sunlight can be well utilized for the photocatalytic degradation of TDZ. The study offers a cheap and effective approach for the photocatalytic degradation of organic pollutants in circumneutral water bodies.

High-performance natural-sunlight-driven Ag/AgCl photocatalysts with a cube-like morphology and blunt edges via a bola-type surfactant-assisted synthesis

Ag/AgCl-based structures have recently been receiving considerable attention as visible-light-driven plasmonic photocatalysts, wherein the fabrication of Ag/AgCl species shaped with an anisotropic morphology is considered to be an efficient way to enhance their performances. While the past decade has witnessed great progress in this direction, it is still strongly desired to initiate a green and low-cost protocol for the synthesis of Ag/AgCl based structures with high catalytic activity. Using a surfactant-assisted synthesis protocol, wherein a cationic bola-type surfactant of chloride counteranions serves both as a reactant (namely, source of chlorine) for the generation of AgCl structures and as a directing template to assist the formation of anisotropic structures, we herein report that cube-like Ag/AgCl with blunt edges could be fabricated simply by dropping an aqueous solution of silver nitrate into an ethanol solution of the hexane-1,6-bis(trimethylammonium chloride) surfactant. Importantly, compared to the sphere-like counterparts manufactured using a conventional tadpole surfactant, the as-fabricated cube-like structures exhibit substantially improved catalytic performances under visible-light or natural-sunlight irradiation. It has been revealed that photogenerated holes might serve as the main active species during the catalytic process. Meanwhile, our results have disclosed that in contrast to the sphere-like Ag/AgCl structures, the as-constructed cube-like structures are relatively enriched with high-index AgCl facets of smaller hole effective mass, which promote a faster carrier transfer, facilitate the migration of the photogenerated holes to the surface to be involved in photocatalytic reactions, and suppress carrier recombination, leading to their enhanced photocatalytic performances. Considering the tremendous diversity of surfactants (bola-, gemini-, polymeric surfactants etc.) with various halide counteranions and their sophisticated template effects, our new strategy might open up new opportunities for silver/silver halide (Ag/AgX, X = Cl, Br, and I)-based plasmonic structures with various morphologies and with superior light-to-chemical energy conversion capability.

In situ deposition of Ag/AgCl on the surface of magnetic metal-organic framework nanocomposite and its application for the visible-light photocatalytic degradation of Rhodamine dye

Herein, NH₂-MIL-125(Ti) (NMT) as one of the known stable metal-organic frameworks (MOFs) in aqueous solution was successfully magnetized with CoFe₂O₄ nanoparticles through the hydrothermal method. The Ag/AgCl as a plasmonic photocatalyst was assembled on the CoFe₂O₄/NMT (CFNMT) at room temperature by in situ deposition, and photo-reduction methods to improve the photocatalytic activity of CFNMT under LED visible light. The prepared materials were fully characterized by SEM/EDX, TEM, FTIR, XRD, UV-DRS, and VSM analysis. Rhodamin B (RhB) was selected as the pollutant model. The results showed that the Ag/AgCl@CFNMT had super-fast degradation ability of RhB molecule due to the synergetic effect between Ag/AgCl and CFNMT in comparison with NMT and CFNMT. The introduced Ag/AgCl on the surface of CFNMT increased absorption of photons in the visible region and enhanced the transfer and separation of the produced charge on the contact area between Ag/AgCl and CFNMT. Also, after seven times recycling, besides the simple magnetic separation of Ag/AgCl@CFNMT from liquid media, the composite still showed high photodegradation ability (89%).

One-pot sonochemical synthesis of 3D flower-like hierarchical AgCl microsphere with enhanced photocatalytic activity

A highly uniform 3D flower-like hierarchical AgCl microsphere was prepared by sonochemical method with the existence of β-dextrin. The 3D flower-like hierarchical structure can be ascribed to the existence of β-dextrin, which provides nucleation sites for the growth of nanosheets because of the strong interaction between β-dextrin and Ag⁺. The 3D flower-like hierarchical AgCl microspheres were assembled by numerous interleaving nanosheet petals with small thickness. Benefiting from the unique structural features, the as-prepared 3D flower-like hierarchical AgCl microsphere exhibited higher degradation efficiency with degrading 98.17% of methylene blue (MB) and 88.50% of tetracycline (TC) within 40 min, which were both remarkably higher than those of irregular AgCl under visible light irradiation. Besides, the photocatalytic degradation rate constant of 3D flower-like hierarchical AgCl microsphere (0.063 min^-1) for MB was 3.94 times higher than that of irregular AgCl (0.016 min^-1). Moreover, a possible mechanism for the formation and excellent photocatalytic performance of 3D flower-like hierarchical AgCl microsphere was also proposed.

Nanostructured g-C3N4/AgI composites assembled by AgI nanoparticles-decorated g-C3N4 nanosheets for effective and mild photooxidation reaction

AgI nanoparticles-decorated g-C₃N₄ nanosheets with enhanced visible-light photocatalytic activity for the mild photooxidation of 1,4-DHP into its pyridine derivatives.

Efficient removal of organic and bacterial pollutants by Ag-La0.8Ca0.2Fe0.94O3-δ perovskite via catalytic peroxymonosulfate activation

Removal of toxic organics and bacterial disinfection are important tasks in wastewater treatment. Most heavy metal-based catalysts for degradation of aqueous organic pollutants in heterogeneous Fenton-like processes suffer from the toxicity of leached metals. The present work reports environmentally benign systems for both degradation of organics and bacterial disinfection. Calcium substituted LaFeO_3-δ perovskite was demonstrated as an efficient catalyst to activate peroxymonosulfate (PMS) for degradation of phenol, methylene blue and rhodamine 6 G. Compared to LaFeO_3-δ and nanocrystal Fe₃O₄, the lattice oxygen vacancies in B-site cation-deficient perovskite of La_0.8Ca_0.2Fe_0.94O₃-_δ (LaCaFeO_3-δ) particles renders this material a greatly improved catalytic performance. Electron paramagnetic resonance (EPR) suggested that both sulfate (SO₄-) and hydroxyl radicals (OH) played critical roles in the advanced oxidation processes. Moreover, silver doped perovskite (Ag-LaCaFeO_3-δ)/PMS successfully inhibited the growth of waterborne pathogen Escherichia coli and Methicillin-resistant Staphylococcus aureus (MRSA) at a lower dose than silver ions, proving a synergetic effect between free radicals and Ag⁺ in killing the bacteria. Therefore, Ag-LaCaFeO_3-δ/PMS would be promising for practical wastewater treatment.

A novel environmentally sustainable synthesis of Au–Ag@AgCl nanocomposites and their application as an efficient and recyclable catalyst for quinoline synthesis

An eco-friendly synthesis of Au–Ag@AgCl NCs was described using the tuber extract of Nephrolepis cordifolia. The synthetic utility of the NCs was demonstrated by the synthesis of pharmaceutically important quinoline derivatives.

Highly efficient visible-light-driven plasmonic photocatalysts based on graphene oxide mediated hybridization of graphite and Ag/AgBr

Graphite (Gr) has been facilely hybridized with Ag/AgBr under the assistance of graphene oxide (GO). The as-produced Gr/GO/Ag/AgBr displays substantially boosted photocatalytic performances compared to Ag/AgBr, GO/Ag/AgBr, and Gr/Ag/AgBr.

Cube-like Ag/AgCl fabricated via a photoirradiation method and its substantially boosted plasmonic photocatalytic reactivity by an oxidation–chloridization treatment

Cube-like Ag/AgCl species are produced by a photoirradiation method, where substantially boosted plasmonic photocatalytic reactivity has been realized via an oxidation–chloridization treatment.

Mechanistic understanding of ternary Ag/AgCl@La(OH)3 nanorods as novel visible light plasmonic photocatalysts

A new visible light mechanism was revealed for ternary Ag/AgCl@La(OH)₃ nanorods with highly enhanced activity toward NO removal.

Construction of AgCl/Ag/BiOCl with a concave-rhombicuboctahedron core–shell hierarchitecture and enhanced photocatalytic activity

Concave-rhombicuboctahedron structure Ag/AgCl/BiOCl heterojunction photocatalyst with high efficiency and stability is prepared through a simple one-step vapor diffusion strategy at room temperature without template or any additives.

Facile solvothermal synthesis of a high-efficiency CNNs/Ag/AgCl plasmonic photocatalyst

A CNNs/Ag/AgCl (defined as CNAAC) plasmonic photocatalyst with efficient photocatalytic degradation ability was obtained by depositing Ag/AgCl nanoparticles on g-C₃N₄ nanosheets (CNNS).

Spherical and sheetlike Ag/AgCl nanostructures: interesting photocatalysts with unusual facet-dependent yet substrate-sensitive reactivity

We herein report that spherical and sheetlike Ag/AgCl nanostructures could be controllably synthesized by means of chemical reactions between AgNO3 and cetyltrimethylammonium chloride (CTAC) surfactant. In this synthesis system, AgNO3 works as the silver source, while CTAC serves not only as the chlorine source but also as the directing reagent for a controllable nanofabrication. We show that compared to the spherical Ag/AgCl nanostructures, the sheetlike counterparts, wherein the AgCl nanospecies are predominantly enriched with {111} facets, could exhibit superior catalytic performances toward the photodegradation of methyl orange. Interestingly, we further demonstrate that when 4-chlorophenol or phenol is used as the substrate, the sheetlike Ag/AgCl nanostructures exhibit inferior catalytic reactivity, whereas the spherical counterparts display superior catalytic performances comparatively. Our results disclose new insights on the facet-dependent catalytic performances with regard to a facet-selective but substrate-sensitive photoinduced electron-hole separation.

Visible-light-driven Ag/AgCl plasmonic photocatalysts via a surfactant-assisted protocol: enhanced catalytic performance by morphology evolution from near-spherical to 1D structures

Fibrous Ag/AgCl structures with boosted photocatalytic performances have been fabricatedviaa one-pot surfactant-assisted morphology evolution from near-spherical to 1D architectures.

Pristine graphdiyne-hybridized photocatalysts using graphene oxide as a dual-functional coupling reagent

Pristine graphdiyne has been hybridized with Ag/AgBr using graphene oxide as a coupling reagent, and enhanced photocatalytic performances have been realized.

(Hollow Au–Ag nanoparticles)–TiO2 composites for improved photocatalytic activity prepared from block copolymer-stabilized bimetallic nanoparticles

(Hollow AuAg nanoparticles)–TiO₂ composite particles, showing higher photocatalytic activity, have been prepared.

Sustainable synthesis of highly efficient sunlight-driven Ag embedded AgCl photocatalysts

Microbe-free broth synthesis was performed under solar light to give Ag nanoparticle embedded AgCl in 5 minutes with superior performance than P25 for organic pollutant degradation.

Light converting phosphor-based photocatalytic composites

Light-conversion phosphor-based composites including up-conversion, down-conversion, and long afterglow phosphor-semiconductors for efficient photocatalysis are summarized.

Enhancing the visible-light-induced photocatalytic activity of AgNbO3 by loading Ag@AgCl nanoparticles

A new visible-light-driven plasmonic photocatalyst Ag@AgCl/AgNbO₃ is prepared via loading with Ag@AgCl nanoparticles by an impregnating precipitation photoreduction method.

Synthesis of AgCl hollow cubes and their application in photocatalytic degradation of organic pollutants

The formation process and a typical FESEM image of AgCl hollow cubes.

In situ ion exchange synthesis of strongly coupled Ag@AgCl/g-C₃N₄ porous nanosheets as plasmonic photocatalyst for highly efficient visible-light photocatalysis

A novel efficient Ag@AgCl/g-C3N4 plasmonic photocatalyst was synthesized by a rational in situ ion exchange approach between exfoliated g-C3N4 nanosheets with porous 2D morphology and AgNO3. The as-prepared Ag@AgCl-9/g-C3N4 plasmonic photocatalyst exhibited excellent photocatalytic performance under visible light irradiation for rhodamine B degradation with a rate constant of 0.1954 min(-1), which is ∼41.6 and ∼16.8 times higher than those of the g-C3N4 (∼0.0047 min(-1)) and Ag/AgCl (∼0.0116 min(-1)), respectively. The degradation of methylene blue, methyl orange, and colorless phenol further confirmed the broad spectrum photocatalytic degradation abilities of Ag@AgCl-9/g-C3N4. These results suggested that an integration of the synergetic effect of suitable size plasmonic Ag@AgCl and strong coupling effect between the Ag@AgCl nanoparticles and the exfoliated porous g-C3N4 nanosheets was superior for visible-light-responsive and fast separation of photogenerated electron-hole pairs, thus significantly improving the photocatalytic efficiency. This work may provide a novel concept for the rational design of stable and high performance g-C3N4-based plasmonic photocatalysts for unique photochemical reaction.

Advanced nanoarchitectures of silver/silver compound composites for photochemical reactions

Silver/silver compound (SSC) composites have received much attention as a type of potential materials in photochemical reactions due to their high efficiency, facile syntheses and availability of raw materials. This article reviews the state-of-the-art progress on the advanced nanoarchitectures of SSC composites. We begin with a survey on the general synthetic strategies for SSC composites, and then step into relatively detailed methods for size and morphology tunable two-component and more delicate multi-component SSC nanostructures. In addition, the electronic structure-related mechanisms of such materials and the recent studies on their stability are summarized. This review also highlights some perspectives on challenges related to the SSC composites and the possible research in the future.

Silver iodide microstructures of a uniform towerlike shape: morphology purification via a chemical dissolution, simultaneously boosted catalytic durability, and enhanced catalytic performances

The fabrication of microstructures/nanostructures of a uniform yet well-defined morphology has attracted broad interest from a variety of fields of advanced functional materials, especially catalysts. Most of the conventional methods generally suffer from harsh synthesis conditions, requirement of bulky apparatus, or incapability of scalable production, etc. To meet these formidable challenges, it is strongly desired to develop a facile, cost-effective, scalable method to fulfill a morphology purification. By a precipitation reaction between AgNO3 and KI, we report that irregular AgI structures, or their mixture with towerlike AgI architectures could be fabricated. Compared to the former, the mixed structures exhibit enhanced catalytic reactivity toward the photodegradation of Methyl Orange pollutant. However, its catalytic durability, which is one of the most crucial criteria that are required by superior catalysts, is poor. We further show that the irregular structures could be facilely removed from the mixture via a KI-assisted chemical dissolution, producing AgI of a uniform towerlike morphology. Excitingly, after such simple morphology purification, our towerlike AgI displays not only a boosted catalytic durability but also an enhanced catalytic reactivity. Our chemical dissolution-based morphology purification protocol might be extended to other systems, wherein high-quality advanced functional materials of desired properties might be developed.

Sunlight-driven Ag-AgCl(1-x)Br(x) photocatalysts: enhanced catalytic performances via continuous bandgap-tuning and morphology selection

The solid solution (SS) method is an effective way to design impactful photocatalysts, owing to its merit of continuous bandgap-tuning. A calcination, usually breaking the morphology of a material, has to be used to synthesize such catalysts, although the morphology is a critical issue affecting its catalytic behavior. It thus is strongly desired to construct SS-based catalysts with a shaped morphology. Here, we report that AgCl(1-x)Br(x) SS-based photocatalysts, Ag-AgCl(1-x)Br(x), with a shaped morphology, can be produced via an ion-exchange between nanostructured Ag-AgCl and KBr. It is found that when sphere-like Ag-AgCl is employed as a precursor, the Ag-AgCl(1-x)Br(x), maintains its morphology when x is in the range of 0-1. The bandgap, and the catalytic activities of these Ag-AgCl(1-x)Br(x) for the degradation of methyl orange, display a monotonic narrowing and a continuous enhancement, respectively, with the increase of x. In contrast, when cube-like Ag-AgCl is used as a precursor, the Ag-AgCl(1-x)Br(x) preserves its morphological features when x ≤ 0.5, while a morphology distortion is observed when x ≥ 0.75. Fascinatingly, although the bandgap of thus-constructed Ag-AgCl(1-x)Br(x) also exhibits a monotonic narrowing with the increase of x, they (x ≠ 0, 1) display enhanced catalytic activity compared with the two terminal materials, Ag-AgCl and Ag-AgBr, wherein Ag-AgCl0.5Br0.5, with a cube-like morphology, shows the highest catalytic performance. The synergistic effect of morphology selection and bandgap narrowing plays an important role for these intriguing new findings. Our work provides a unique forum for an optimized selection of SS-based photocatalysts in terms of morphology selection and bandgap-tuning.