Hierarchical visible-light-response Ag/AgCl@TiO2 plasmonic photocatalysts for organic dye degradation

Green approach for the fabrication of a ternary nanocatalyst (Ag-ZnONPs@Cy) for visible light-induced photocatalytic reduction of nitroarenes to aminoarenes

In recent times, the incorporation of metal oxide nanoparticles with organic dyes has piqued the interest of numerous researchers due to their diverse applications under visible light instead of UV radiation. This investigation employed a three-step methodology to fabricate cyanidin-sensitized silver-doped zinc oxide nanoparticles (Ag-ZnO@Cy). Initially, cyanidin dye was extracted from fresh black mulberry fruit, followed by the eco-friendly synthesis of Ag-ZnO nanoparticles (Ag-ZnONPs). The successful integration of the prepared cyanidin dye with Ag-ZnONPs was achieved through a straightforward, environmentally benign, and cost-efficient procedure. The resultant ternary composite underwent comprehensive characterization and confirmation utilizing various techniques, such as SEM, FT-IR, EDX, DRS, elemental mapping, and XRD. The experimental results for Ag-ZnONPs@Cy demonstrated that the nanocrystalline wurtzite exhibited spherical shapes with an average crystal size of 27.42 nm. Moreover, the photocatalytic activity of the synthesized Ag-ZnONPs@Cy was meticulously investigated under blue LED light irradiation. This inquiry encompassed examinations of catalyst amount, regeneration, stability, reusability, and the influence of light source on the hydrogenation of nitroarenes to the corresponding aminoarenes. The findings shed light on the potential of this composite for diverse photocatalytic applications.

Multi-functional silver nanoprism-titanium dioxide hybrid nanoarrays for trace-level SERS sensing and photocatalytic removal of hazardous organic pollutants

Owing to the excellent optoelectronic properties of metal nanoparticle-semiconductor interfaces; hybrid substrates with superior catalytic and sensing properties can be designed. In the present study, we have attempted to evaluate anisotropic silver nanoprisms (SNP) functionalized titanium dioxide (TiO₂) particles for multifunctional applications such as SERS sensing and photocatalytic decomposition of hazardous organic pollutants. Hierarchical TiO₂/SNP hybrid arrays have been fabricated via facile and low-cost casting techniques. The structural, compositional, and optical characteristics of TiO₂/SNP hybrid arrays were well elucidated and correlated to SERS activities. SERS studies revealed that TiO₂/SNP nanoarrays possess almost 288 times enhancement compared to bare TiO₂ substrates and 2.6 times enhancement than pristine SNP. The fabricated nanoarrays demonstrated detection limits down to 10^-12 M concentration levels and lower spot-to-spot variability of ∼ 11%. The photocatalytic studies showed that almost 94 and 86% of rhodamine B and methylene blue were decomposed within 90 min of visible light exposure. Besides, two times enhancement in photocatalytic activities of TiO₂/SNP hybrid substrates was also observed than bare TiO₂. The highest photocatalytic activity was exhibited by SNP to TiO₂ molar ratio of 1.5 × 10^-3. The electrochemical surface area and the interfacial electron-transfer resistance were increased with the increment in TiO₂/SNP composite load from 3 to 7 wt%. Differential Pulse Voltammetry (DPV) analysis revealed a higher RhB degradation potential of TiO₂/SNP arrays than SNP or TiO₂. The synthesized hybrids exhibited excellent reusability without any significant deterioration in photocatalytic properties over five successive cycles. TiO₂/SNP hybrid arrays were proved to be multiple platforms for sensing and degrading hazardous pollutants for environmental applications.

Grafting a Porous Metal-Organic Framework [NH2-MIL-101(Fe)] with AgCl Nanoparticles for the Efficient Removal of Congo Red

Organic dyes can produce harmful effects on the water environment, such as affecting the growth of aquatic organisms, reducing the transparency of water bodies, and causing eutrophication of water bodies, so it is necessary to mitigate the hazards of organic dyes. In this study, a metal-organic framework [NH₂-MIL-101(Fe)] was synthesized by the solvothermal method as a carrier for the in situ uniform deposition of AgCl nanoparticles on its surface, which was successfully used for both adsorption and degradation of Congo red. Adsorption results showed that the adsorption kinetics conformed to the proposed secondary adsorption kinetics equation with a maximum adsorption capacity of 248.4 mg·g^-1. Furthermore, the degradation results indicated that with the aid of sodium borohydride as a reducing agent, the degradation of Congo red followed pseudo-first-order kinetics with a degradation rate of 0.077 min^-1, and the complete degradation of Congo red was finished within 18 min. Therefore, AgCl/NH₂-MIL-101(Fe) may find a potential application in the removal of dyes from wastewater.

Synthesis of Electrospun PAN/TiO2/Ag Nanofibers Membrane As Potential Air Filtration Media with Photocatalytic Activity

The PAN/TiO2/Ag nanofibers membrane for air filtration media was successfully synthesized with electrospinning method. The morphology, size, and element percentage of the nanofiber were characterized by a scanning electron microscopy-energy dispersive spectroscopy, while X-ray fluorescence and FTIR were used to observe the chemical composition. The water contact angle and UV-vis absorption were measured for physical properties. Performance for air filtration media was measured by pressure drop, efficiency, and quality factor test. TiO2 and Ag have been successfully deposited in nonuniform 570 nm PAN/TiO2/Ag nanofibers. The nanofiber membrane had hydrophilic surface after TiO2 and Ag addition with a water contact angle of 34.58°. UV-vis data showed the shifting of absorbance and band gap energy of nanofibers membrane to visible light from 3.8 to 1.8 eV. The 60 min spun PAN/TiO2/Ag nanofibers membrane had a 96.9% efficiency of PM2.5, comparable to results reported in previous studies. These properties were suitable to be applied on air filtration media with photocatalytic activity for self-cleaning performance.

Photocatalytic oxidation of nitric oxide over AgNPs/TiO2-loaded carbon fiber cloths

Series of AgNPs/TiO₂-loaded carbon fiber cloth (CFC) composites were prepared by incorporation of pristine TiO₂ and three AgNPs-modified TiO₂ additives onto the surface of four commercial CFCs. AgNPs/TiO₂ photocatalysts were synthesized by the wet impregnation method, including NaBH₄ reduction of silver ions. The silver content in the modified photocatalyst was assessed by inductively coupled plasma optical emission spectrometry (ICP-OES) as well as XRD analysis. It can be indicated that silver was successfully reduced to Ag nanoparticles what was confirmed by UV-Vis/DRS as well as XRD methods. The photocatalytic activity of the AgNPs/TiO₂-loaded CFCs was evaluated during the photocatalytic oxidation (PCO) tests of nitric oxide (NO) acting as a model air contaminant under UV light. It was found that the highest NO removal rate was observed for the AgNPs/TiO₂-loaded CFC material containing 3.70 wt% of AgNPs. Modification of TiO₂ with AgNPs stabilized the photocatalytic efficiency of the composites during 5 as well as 24 consecutive NO photooxidation cycles. It was also concluded that the presence of AgNPs was a key factor responsible for hindering NO₂ formation.

Enhanced Photocatalytic Activity of Nanoparticle-Aggregated Ag-AgX(X = Cl, Br)@TiO2 Microspheres Under Visible Light

Ag-AgX(X = Cl, Br)@TiO₂ nanoparticle-aggregated spheres with different mass ratio of R = TiO₂/Ag(X) from 35:1 to 5:1 were synthesized by a facile sol-gel technique with post-photoreduction. The photocatalytic activities of both Ag-AgCl@TiO₂ and Ag-AgBr@TiO₂ under visible light are effectively improved by ~3 times relative to TiO₂ NPAS under the simulated sunlight for the decomposition of methyl orange (MO). Ag-AgBr@TiO₂ showed 30% improvement and less stable in photocatalytic activity than that of AgCl@TiO₂. The role of Ag and AgX nanoparticles on the surface of Ag-AgX(X = Cl, Br)@TiO₂ was discussed. Ag on these samples not only can efficiently harvest visible light especially for AgCl, but also efficiently separate excited electrons and holes via the fast electron transfer from AgX(X = Cl, Br) to metal Ag nanoparticles and then to TiO₂-aggregated spheres on the surface of heterostructure. On the basis of their efficient and stable photocatalytic activities under visible-light irradiation, these photocatalysts could be widely used for degradation of organic pollutants in aqueous solution.

Sonochemical co-deposition of antibacterial nanoparticles and dyes on textiles

The sonochemical technique has already been proven as one of the best coating methods for stable functionalization of substrates over a wide range of applications. Here, we report for the first time on the simultaneous sonochemical dyeing and coating of textiles with antibacterial metal oxide (MO) nanoparticles. In this one-step process the antibacterial nanoparticles are synthesized in situ and deposited together with dye nanoparticles on the fabric surface. It was shown that the antibacterial behavior of the metal oxides was not influenced by the presence of the dyes. Higher K/S values were achieved by sonochemical deposition of the dyes in comparison to a dip-coating (exhaustion) process. The stability of the antibacterial properties and the dye fastness was studied for 72 h in saline solution aiming at medical applications.

One pot microwave-assisted synthesis of Ag decorated yolk@shell structured TiO2 microspheres

A facile and extremely fast one-pot microwave-assisted synthesis of Ag decorated yolk@shell structured TiO₂ microspheres was reported.

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.

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.

Graphene oxide/α-Bi(2)O(3) composites for visible-light photocatalysis, chemical catalysis, and solar energy conversion

The growing challenges of environmental purification by solar photocatalysis, precious-metal-free catalysis, and photocurrent generation in photovoltaic cells receive the utmost global attention. Here we demonstrate a one-pot, green chemical synthesis of a new stable heterostructured, ecofriendly, multifunctional microcomposite that consists of α-Bi2 O3 microneedles intercalated with anchored graphene oxide (GO) microsheets (1.0 wt %) for the above-mentioned applications on a large economical scale. The bare α-Bi2 O3 microneedles display two times better photocatalytic activities than commercial TiO2 (Degussa-P25), whereas the GO-hybridized composite exhibits approximately four to six times enhanced photocatalytic activities than the neat TiO2 photocatalyst in the degradation of colored aromatic organic dyes (crystal violet and rhodamine 6G) under visible-light irradiation (300 W tungsten lamp). The highly efficient activity is associated with the strong surface adsorption ability of GO for aromatic dye molecules, the high carrier acceptability, and the efficient electron-hole pair separation in Bi2 O3 by individual adjoining GO sheets. The introduction of Ag nanoparticles (2.0 wt %) further enhances the photocatalytic performance of the composite over eightfold because of a plasmon-induced electron-transfer process from Ag nanoparticles through the GO sheets into the conduction band of Bi2 O3 . The new composites are also catalytically active and catalyze the reduction of 4-nitrophenol to 4-aminophenol in the presence of borohydride ions. Photoanodes assembled from GO/α-Bi2 O3 and Ag/GO/α-Bi2 O3 composites display an improved photocurrent response (power conversion efficiency ∼20 % higher) over those prepared without GO in dye-sensitized solar cells.

SiO2@Ag/AgCl: a low-cost and highly efficient plasmonic photocatalyst for degrading rhodamine B under visible light irradiation

The micro/nano-structure composite SiO₂@Ag/AgCl was employed as a low cost photocatalyst for the degradation of RhB in aqueous solution under visible light irradiation, which exhibited excellent photocatalytic performance and stability.