Ag TiO2 Research Articles

Difference in High-Temperature Tribological Performance of Oxide/Ag-MoS2-Based Composites

MoS2 has excellent vacuum lubricating performance. However, it is prone to be oxidized in a high-temperature atmospheric environment, leading to the deterioration of its lubricating performance and even serious space accidents. The high-temperature lubricating performance of MoS2-based solid lubricating materials can be improved to some extent by the co-compounding of appropriate oxides and Ag. The tribological properties of several common nano-oxides (ZnO, TiO2, Al2O3, and ZrO2) composited with metal Ag of MoS2-based composites were compared at 450 °C. The results showed that the comprehensive tribological performance of MoS2-TiO2-Ag was the best, an the average friction coefficient of about 0.26, and a wear rate of about 1.2 × 10−5 mm3/Nm, which was 18% and 43% lower than that of MoS2-Ag, respectively. The excellent tribological properties of MoS2-TiO2-Ag composites were attributed to three aspects: Firstly, with the help of the oxidation resistance of TiO2 to MoS2 to some extent and its high ionic potential, its oxidation resistance was improved and its shear strength was reduced to provide low friction. Secondly, relying on the low shear strength and good film-forming tendency of soft metal Ag on the sliding surface, a low shear tribo-film was easily formed on the friction interface, which was helpful for the synergistic lubrication of Ag, MoS2, and TiO2.Thirdly, through the matching of hard TiO2 and soft Ag, the wear resistance and bearing capacity of the composites were improved to some extent. The research results can provide some reference for the selection and design of MoS2-based high-temperature lubricating materials and the enhancement of their tribological properties.

Fluorinated B-72 hybrid silver doped modified nanoparticle as a coating for biological corrosion protection of ancient bricks

In this paper, a superhydrophobic organic-inorganic composite coating containing fluorinated B72 hybrid methyl-modified silica/(Ag doped TiO2) by hexamethyldisilazane (HMDS) (H-SiO2/Ag/TiO2) was prepared by means of a mild and an environmental friendly method. Transparency, adhesion, hardness tests and photocatalytic performance were measured to determine the content of Ag in TiO2 which the TiO2/AgNO3 ratio is 0.008 g/mL. The synthesized Ag/TiO2 nanoparticles were characterized by X-ray diffraction (XRD), Raman spectra and transmission electron microscope (TEM). The highest contact angle of coated ancient bricks was 148.66° and the color change value of ΔE⁎ before and after coating was <5 which is within an acceptable range. The physical properties such as apparent porosity and water vapor permeability (ΔMp) were studied. After weathering from acid, alkali, salt, water and ultraviolet radiation, the bricks coated by the composite coatings still have good hydrophobicity that the contact angle were >120° and minor degree of surface corrosion comparing with the ancient bricks. The inhibitory effect of the composite coating on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), and that on algae (Chlamydomonas and Dunaliella) were studied through bacteriostasis test and algae comparative experiments, respectively. Finally, the mechanism of the composite coating on antibacterial and anti-algae was studied. The results showed that the appearance of the ancient bricks was not changed after coating, and the anti-weathering, antibacterial and anti-algae properties of the ancient transformation were increased.

Enhanced Schottky barrier engineering in silver-doped TiO2/p-Si heterojunctions: Insights into electrical behavior and charge carrier dynamics

Heterojunctions were fabricated through the deposition of silver-doped Titanium dioxide (Ag–TiO2) onto p-type crystalline silicon, employing the sol-gel technique. Electrical characterization was conducted with varying Ag concentrations. The investigation revealed that the Schottky barriers at each interface (Ag/TiO2 and Si/Ag), along with the built-in potential at the TiO2/p-Si junction, increase proportionally with the Ag concentration. This observed trend was attributed to the reduction in the TiO2 bandgap due to Ag incorporation, resulting in a concurrent shift in both valence and conduction bands. Consequently, there is a growth of the conduction energy discontinuity and a reduction in the valence one, facilitating hole diffusion while impeding electron transfer across the depletion layer. Furthermore, the introduction of Ag leads to a decrease in both electron and hole concentrations. However, Ag incorporation within the TiO2 matrix manifests as nanoparticles and clusters, resulting in a nonhomogeneous distribution of charge carriers across the sample. Impedance analysis indicates an increase in device resistance and a decrease in effective capacitance.

Simulated sunlight-driven photocatalytic activation of peroxydisulfate by core–shell Ag@SiO2/TiO2 nanocomposite for efficient methyl orange degradation

Herein, core–shell Ag@SiO2/TiO2 nanocomposites were synthesized and applied to activate peroxydisulfate (PDS) for wastewater purification. The Ag core and Ag-doped TiO2 shell were obtained by stober method and calcination method. The dispersion degree and size of Ag in TiO2 would influence the oxygen vacancy. Ag enhanced the visible absorption of TiO2 and activated PDS. Improved degradation performance was attributed to enhanced PDS activation by photogenerated e−, which separated h+and thus promoted methyl orange(MO) degradation. Reactive oxidative species were verified under dark and light conditions via quenching experiments and electron paramagnetic resonance tests, demonstrating SO4•–, h+, O2•–, and1O2were formed in light,whereasSO4•–, •OH, O2•–, and 1O2were responsible for MO degradation under dark conditions. The Ag@SiO2/TiO2/PDS/light system showed selectivity for removal of cationic dyes (e.g., methylene blue and malachite green) through adsorption and photocatalysis, whereas anionic dyes (e.g., MO) were degraded by photocatalysis alone. Besides, we found excess adsorption of micropollutant onto catalyst may be adverse to the activation of PDS. Therefore, the adsorption of oxidant (such as PDS) onto the catalyst surface would be beneficial for catalytic activation and micropollutant degradation, especially onto active sites. This work aims to provide a new avenue for core-shell structure catalyst synthesis in wastewater purification.

Assessing the Efficacy of Hybrid Nanofluid within a Non-Newtonian Reiner-Philippoff Model, Incorporating MHD and Thermal Radiation Past a Stretching/Shrinking Sheet

Hybrid nanofluids are making waves in industry because of their superior thermal efficiency and innovative designs. Their usefulness extends to many other sectors and domains of study. The volume fraction of Cu–Al2O3 and Ag–TiO2 hybrid nanoparticles in nanofluids will be studied to determine their impact on heat transmission and flow. The study also considers the presence of heat radiation, a magnetic field, and other relevant factors. The non-Newtonian Reiner-Philippoff model was employed to investigate the flow's shear thickening and thinning properties. The combined effects of suction and a contracting surface form a boundary for the surface. The reduced partial differential equation (PDE) is solved using the MATLAB tool bvp4c following the similarity transformation method. The shrinking sheet shows that the dual solution converges to critical points, and the stability study verified that the first one is stable and physically trustworthy. The mathematical modelling developed for nanofluid hybrids has exhibited a significant impact on the overall heat flow, which can be attributed to the variation in the parameters that influence it. Enhancement in magnetic parameter (+2.26%), suction (+2.99%), and nanoparticle fractional volume of metal oxide (+0.4%) were identified as factors that accelerated heat transfer to the pioneering Cu–Al2O3 nanofluid hybrid, according to the study. Besides, the second hybrid of Ag–TiO2 nanofluids had a reduced heat transfer rate due to changes in thermal radiation (-2.14%) and Reiner parameter-Philippoff fluid (-0.14%).

Investigating bifunctional linker-assisted photocatalytic behavior of Ag–TiO2 nanocomposites

Investigating bifunctional linker-assisted photocatalytic behavior of Ag–TiO2 nanocomposites

Multifunctional daytime radiative cooler resistant to UV aging

Passive radiative cooling presents a promising approach to mitigate global warming and reduce energy consumption. Existing coolers, however, face challenges in practical prolonged adoption due to their unappealing design, susceptibility to environmental pollutants, as well as degradation of polymers by ultraviolet (UV) irradiation from sunlight. This study introduces a multifunctional daytime radiative cooler (MDRC) with a dual-layered structure, combining practical functionality with aesthetic value. Its base layer consists of an Ag–TiO2–Ag thin film stack, imparting vibrant cyan, magenta, and yellow colors, even maintaining visually appealing from various incident angles, up to 75°, to ensure consistent color display. The top layer, comprising S–SiO2 nanospheres with UV resistance rather than polymers, not only forms a superhydrophobic surface with a contact angle of 155.502°, enhancing the self-cleaning capability of the MDRC against contamination and dust, but also renders the MDRC with extraordinary anti-aging capacity. Outdoor experiments has shown that the MDRC maintains operation at temperatures above ambient under direct solar irradiation, achieving a substantial temperature reduction of 6.82 °C compared to the same colored commercial coating. After three months of outdoor exposure, the MDRC demonstrated minimal degradation in performance, with decreases of only 0.29 °C during the day and 0.12 °C at night, underscoring its superior UV-resistant aging properties. This MDRC represents a robust solution for diverse durable outdoor raidative cooling applications, advancing toward real-world utilization.

Antibacterial Activity of Visible Light Responsive‐Silver‐Nanoparticle/Titania Composite Thin Films with Unprecedently Higher Amounts of Silver

AbstractTo study the antibacterial efficacy of metallic Ag nanoparticle/titania (Ag‐NP)/TiO2 composite thin films against Escherichia coli (ATCC 25922), COMP‐Agn with various amounts of Ag (10 mol% ≤ n ≤ 80 mol%) are fabricated on a quartz glass substrate at 600 °C using the molecular precursor method. The films are characterized by X‐ray diffraction, X‐ray photoelectron, scanning electron microscopy, transmission electron microscopy, photoluminescence, and UVvis techniques. The analysis reveals that the films are composed of metallic Ag‐NPs embedded in a mixture of anatase and rutile matrix, with a volumetric fraction of Ag ranging from 0.18 to 0.68. The antibacterial activity of the TiO2 thin film and COMP‐Agn are determined by disk diffusion and viable cell count methods. Neither pure TiO2 nor pure Ag films exhibit any discernible antibacterial under dark and visible light. The antibacterial of Ag content in composite films is observed to persist for a maximum increase of 70%. The model is proposed on the basis of photoexcited electron transfer from Ag NPs to the TiO2 conduction band of COMP‐Agn, which clarifies the main factors affecting the photoresponse and the excellent response to visible light via surface plasmon resonance.

Toxic effect of mussel Mytilus galloprovincialis exposed to Ag–TiO2 and ZnTi2O4–TiO2 bicomponent nanoparticles

Nanoparticles (NPs) are widely used in various fields, including antifouling paints for ships and industrial structures submerged in water. The potential impact of NPs on aquatic organisms, particularly their potential toxicity, is a significant concern, as their negative impact has been relatively poorly studied. In this study, we evaluated the effect of different concentrations of bimetallic Ag–TiO₂ and ZnTi₂O₄-TiO₂ NPs, which could potentially be used in antifouling coatings, on the hemocytes of the Mediterranean mussel Mytilus galloprovincialis. Hemocytes were exposed to NPs at concentrations of 0.1–1 mg/L for 1 and 2 h, and the production of reactive oxygen species (ROS), levels of DNA damage, and number of dead cells were measured. Exposure to Ag–TiO₂ NPs at 1 mg/L concentration for 1 h suppressed ROS production in hemocytes and reduced the relative number of agranulocytes in cell suspensions, without inducing DNA damage or cell death. Exposure to ZnTi2O4–TiO2 NPs did not cause changes in the ratio of granulocytes to agranulocytes in suspensions, nor did it affect other functional parameters of hemocytes. However, after a 2 h exposure period, ZnTi2O4–TiO2 NPs (1 mg/L) significantly reduced the production of ROS by hemocytes. These findings suggest that Ag–TiO2 and ZnTi2O4–TiO2 NPs have low acute toxicity for marine bivalves.

An antimicrobial acrylic polyurethane coating with TiO2-Ag hybrid nanoparticles

Abstract The purpose of this work is to fabricate the advanced organic antibacterial coating containing the strong photocatalytic nanomaterials. For this purpose, firstly the TiO2–Ag hybrid nanoparticles are synthesized by chemical reduction method. Then, the antibacterial coating based on acrylic polyol, polyisocyanate, and these TiO2–Ag hybrid nanoparticles has been prepared. Mechanical properties show that the optimal content of TiO2–Ag hybrid nanoparticles in the coating matrix is 2 wt%, with its abrasion resistance of 166.2 L/mil; impact strength of 195 kg cm; adhesion of size #1 and relative hardness of 0.78. In addition, FE-SEM analysis shows that the nanocomposite coating has a tight structure with homogeneous dispersion of TiO2–Ag nanoparticles in the polymer matrix. The paint film has good antibacterial activity and has great application prospects. Data from the antibacterial test indicates that in the presence of an acrylic polyurethane coating containing 2 wt% TiO2–Ag, the number of viable Escherichia coli decreased from 3.4 × 105 CFU/ml to 1.5 × 102 CFU/ml after 24 h of culture.

Comparison of nanomaterial Ag and nanomaterial TiO2 in food fields

Comparison of nanomaterial Ag and nanomaterial TiO2 in food fields

Amplifying Photoelectrocatalytic D2O Splitting with Ag–TiO2 Janus Particles: Interfacial Effects Unveiled

Amplifying Photoelectrocatalytic D₂O Splitting with Ag–TiO₂ Janus Particles: Interfacial Effects Unveiled

Nanometals incorporation into active and biodegradable chitosan films

This study investigates the effects of incorporating ZnO, TiO2, and colloidal Ag nanoparticles on the antioxidant, antimicrobial, and physical properties of biodegradable chitosan films. The research focuses on addressing the growing demand for sustainable packaging solutions that offer efficient food preservation while mitigating environmental concerns. In this investigation, the physical properties including thickness, water content, solubility, swelling degree, tensile strength, and elasticity of the chitosan films were examined. Additionally, the samples were analyzed for total polyphenol content, antimicrobial activity, and antioxidant capacity. Notably, the incorporation of ZnO nanoparticles led to the lowest water content and highest strength values among the tested films. Conversely, the addition of colloidal Ag nanoparticles resulted in films with the highest antioxidant capacities (DPPH: 32.202 ± 1.631 %). Remarkably, antimicrobial tests revealed enhanced activity with the inclusion of colloidal silver nanoparticles, yet the most potent antimicrobial properties were observed in films containing ZnO (E.coli: 2.0 ± 0.0 mm; MRSA: 2.0 ± 0.5 mm). The findings of this study hold significant implications for the advancement of edible biodegradable films, offering potential for more efficient food packaging solutions that address environmental sustainability concerns. By elucidating the effects of nanoparticle incorporation on film properties, this research contributes to the ongoing discourse surrounding sustainable packaging solutions in the food industry.

A sensitivity-enhanced plasmonic sensing platform modified with Co(OH)2 nanosheets

In the detection of biomolecules, surface plasmon resonance (SPR) sensors require high sensitivity. In this study, we propose a sensitivity-enhanced functionalized plasmonic interface based on Ag–TiO2–Co(OH)2 nanosheets structure. Compared to unmodified SPR sensors, the sensitivity of the sensor decorated with TiO2 and Co(OH)2 nanosheets is increased by 130.84%, reaching 5764.27 nm/RIU. This enhancement is attributed to the high refractive index of the coating, as well as the high specific surface area and abundant active sites provided by the synthesized Co(OH)2 nanosheets with a multi-grooved structure. Additionally, employing a double-antibody sandwich method, the antibody-functionalized plasmonic interface enables specific detection of human serum albumin (HSA). The linear response of this sensor was in the wide range of 0.4–150 μM, and the LOD reached 154.89 nM(KD is approximately 1.73 × 10−6 M). This novel SPR sensor offers a new strategy for biochemical sensing and provides a highly sensitive platform for immunoassays.

Silver doped anatase nanocomposite: a novel photocatalyst with advanced activity under visible light for waste-water treatment

Anatase is a universal semiconductor photocatalyst; however, its wide band-gap energy limits its entire solar spectrum absorption to only 5%. Anatase could be activated in the visible region via nobel metal deposition. This study reports on the facile synthesis of colloidal mono-dispersed anatase nanoparticles of 5 nm particle size via hydrothermal synthesis. Nobel metals (Silver, Nickel) were deposited on colloidal anatase surface. The photocatalytic activities of Ag–TiO2, and Ni–TiO2 were investigated for the degradation of basic fuchsin dye. Ag–TiO2 nanocomposite demonstrated enhanced adsorption activity in dark, as well as superior photocatalytic. Ag–TiO2 nanocomposite demonstrated enhanced removal efficiency by 70.8% under visible irradiation to virgin anatase. Ag–TiO2 nanocomposite demonstrated enhanced oxygen-lattice with low binding energy using XPS analysis. Ag–TiO2 experienced band gap energy of 2.35 eV compared with 3.2 eV for virgin anatase; this feature could secure enhanced solar absorption. Ag–TiO2 demonstrated excellent photo-degradation efficiency of 88% with 0.3% H2O2 under visible light. Deposited silver could catalyze H2O2 decomposition and could promote free radical generation; Ag–TiO2 nanocomposite is a promising photocatalyst for wastewater treatment applications.

Facile green synthesis of Ag doped TiO2 nanoparticles using maple leaf for bisphenol-A degradation and its antibacterial properties

Significant advancements are being made in environmentally friendly chemistry through the use of biosynthetic techniques for material synthesis. This study presents a novel and eco-conscious method for producing silver-doped TiO2 (Ag–TiO2) nanoparticles using maple leaves extract.. The synthesis process ingeniously involves combining maple leaf extract with silver and titanium dioxide precursors. Using advanced characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), reveals the characteristic crystal structure, surface complexity and fascinating morphology of the nanoparticles. These results explain the remarkable catalytic ability of Ag–TiO2 nanoparticles (NPs) in effectively degrading BPA under visible and ultraviolet (UV) light irradiation. Ag–TiO2 NPs show the BPA degradation of 94.42% (visible) and 96.83% (UV). In addition, these nanoparticles demonstrate good ability to combat a wide range of threatening pathogenic bacteria. The doping of Ag into TiO2 reveals the enhancement of inhibition growth against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli). This work opens up broad potential for applications in the treatment of BPA-containing wastewater and the development of environmentally friendly antimicrobial materials.

Heat transfer analysis of hydromagnetic hybrid nanofluid (H2O) containing Ag–TiO2 nanoparticles in a slanted triangular enclosure with heated fins

Heat transfer analysis of hydromagnetic hybrid nanofluid (H2O) containing Ag–TiO2 nanoparticles in a slanted triangular enclosure with heated fins

Synergistic effects of micronanobubbles and AC/Ag–TiO2 nanocomposites in photocatalytic process

The AC/Ag–TiO2 nanocomposites were prepared by sol-gel method using different concentrations of Ag. Comprehensive characterization of the crystalline structure, surface morphology, elemental composition, and optical properties of the AC/Ag–TiO2 photocatalysts was carried out using XRD, FTIR, SEM, EDX, TEM, and UV–vis DRS techniques. Consequently, a detailed investigation into the photocatalytic degradation of Indigo Carmine (IC) and Reactive Black 5 (RB5) dyes was conducted, thoroughly examining the involved photocatalytic mechanisms. The study revealed promising outcomes, particularly with the hybrid photocatalyst AC/0.5%Ag–TiO2, showcasing enhanced characteristics in both photooxidation and absorption processes, thereby boosting overall efficacy for IC (70.15%) and RB5 (69.9%). Remarkably, the introduction of small air bubbles significantly improved the removal efficiency of IC and RB5 dyes, achieving removal levels of 93.66% and 88.66%, respectively. The utilization of these micro-nanobubble systems (MNBs) resulted in notably higher first-order reaction constants compared to scenarios without MNBs, indicating the pivotal role of the photocatalyst in dye removal processes. Additionally, the photocatalyst showed unmatched efficacy in eliminating the pesticide carbaryl, attaining 100% removal with and without the presence of MNBs. Moreover, the AC/Ag–TiO2 photocatalyst exhibited significant inhibition of both gram-positive and gram-negative pathogenic bacteria, showcasing its capability to curb their growth even without MNB aeration. This underscores its potential for applications in environmental remediation and microbial control.

Comparative analysis of entropy generation and heat transfer in a tilted partially heated square enclosure using the finite difference method

PurposeIn recent times, there has been a growing interest in buoyancy-induced heat transfer within confined enclosures due to its frequent occurrence in heat transfer processes across diverse engineering disciplines, including electronic cooling, solar technologies, nuclear reactor systems, heat exchangers and energy storage systems. Moreover, the reduction of entropy generation holds significant importance in engineering applications, as it contributes to enhancing thermal system performance. This study, a numerical investigation, aims to analyze entropy generation and natural convection flow in an inclined square enclosure filled with Ag–MgO/water and Ag–TiO2/water hybrid nanofluids under the influence of a magnetic field. The enclosure features heated slits along its bottom and left walls. Following the Boussinesq approximation, the convective flow arises from a horizontal temperature difference between the partially heated walls and the cold right wall.Design/methodology/approachThe governing equations for laminar unsteady natural convection flow in a Newtonian, incompressible mixture is solved using a Marker-and-Cell-based finite difference method within a customized MATLAB code. The hybrid nanofluid’s effective thermal conductivity and viscosity are determined using spherical nanoparticle correlations.FindingsThe numerical investigations cover various parameters, including nanoparticle volume concentration, Hartmann number, Rayleigh number, heat source/sink effects and inclination angle. As the Hartmann and Rayleigh numbers increase, there is a significant enhancement in entropy generation. The average Nusselt number experiences a substantial increase at extremely high values of the Rayleigh number and inclination.Practical implicationsThis numerical investigation explores advanced applications involving various combinations of influential parameters, different nanoparticles, enclosure inclinations and improved designs. The goal is to control fluid flow and enhance heat transfer rates to meet the demands of the Fourth Industrial Revolution.Originality/valueIn a 90° tilted enclosure, the addition of 5% hybrid nanoparticles to the base fluid resulted in a 17.139% increase in the heat transfer rate for Ag–MgO nanoparticles and a 16.4185% increase for Ag–TiO2 nanoparticles compared to the base fluid. It is observed that a 5% nanoparticle volume fraction results in an increased heat transfer rate, influenced by variations in both the Darcy and Rayleigh numbers. The study demonstrates that the Ag–MgO hybrid nanofluid exhibits superior heat transfer and fluid transport performance compared to the Ag–TiO2 hybrid nanofluid. The simulations pertain to the use of hybrid magnetic nanofluids in fuel cells, solar cavity receivers and the processing of electromagnetic nanomaterials in enclosed environments.

Ag‐Decorated Chrysanthemum‐Like CuO–TiO2 Thin Film: Enhanced Photocatalytic Degradation of Rhodamine B

Photocatalysis has attracted attention as a method for purifying pollutants, but how to simply and efficiently prepare catalyst films with high surface areas is still a challenge. Herein, a chrysanthemum‐like CuO–TiO2–Ag photocatalyst is prepared by anodic oxidation and magnetron sputtering. Scanning electron microscopy and energy dispersive spectrometry analyses show that Ag nanoparticles are uniformly modified on the surface of chrysanthemum‐like CuO–TiO2. Moreover, the influences of the thickness of the TiO2 film and the content of Ag nanoparticles on the degradation of rhodamine B (RhB) are studied by controlling the sputtering time. Among the prepared nanocomposites, the chrysanthemum‐like CuO–TiO2‐2.5‐Ag‐2 proves to have the maximal degradation level with regard to RhB by removing 91.16% RhB after 120 min under UV light. This is because the large surface area offers more active sites. In addition, the trapping experiments show that when CuO–TiO2 is decorated by Ag nanoparticles, this contributes to the movement of a number of photogenerated electrons from the conduction band of TiO2 to Ag, thereby improving the efficiency of charge transfer. The findings reveal that the photodegradation efficiency of the prepared nanocomposites in this study is greatly related to the thickness of the TiO2 film and the content of Ag nanoparticles.