All-in-one self-floating porous foams as robust heat-blocking layers for efficient photothermal conversion and solar desalination

Solar-driven interfacial evaporation is a highly efficient and ecofriendly technology for producing freshwater. Herein, self-floating plasmon Ag/black TiO2/carbon porous layered foams (Ag-BTCFs) were demonstrated as efficient solar-thermal convectors using freeze-drying cast-molding and high-temperature surface hydrogenation strategies. This all-in-one three-dimensional (3D) cross-linked self-floating porous layered foam material with full-spectrum absorption can fully harvest sunlight (∼95.45%) and effectively block heat transfer to its sublayer. The synergy of sufficient utilization of absorbed ultraviolet radiation by black TiO2 (b-TiO2), visible light absorption by Ag nanoparticles (Ag NPs) via localized surface plasmon resonance, and near-infrared absorption by layered-amorphous carbon can achieve full-solar-spectrum absorption to concentrate thermal energy. In addition to their synergistic effect, they are conducive to the relaxation of hot electrons when utilizing photogenerated holes to degrade pollutants in domestic wastewater. The steam generation efficiency of Ag-BTCFs is up to 1.79 kg m-2h-1 due to their solar energy conversion efficiency of 81.74% under 1 sun irradiation, which is five times higher than the evaporation rate of pure water. Notably, the material's efficient ion removal rate of 99.80% for solar desalination indicates its high potential for various applications. This strategy provides new insights for fabricating recyclable heat-blocking layer systems against thermal loss to enhance solar steam generation.

Core-shell cadmium sulphide @ silver sulphide nanowires surface architecture: Design towards photoelectrochemical solar cells

Design and development of cadmium sulphide core with silver sulphide shell assembly in nanowire (NWs) surface architecture has been explored through room temperature, simple chemical route towards photoelectrochemical solar cell application. Incorporation of low band gap Ag₂S nanoparticles over the outer surface of the chemical bath deposited CdS NWs has been achieved by simple cation exchange route based on negative free energy of formation. Shell optimization has been performed by investigating structure, surface morphologies and optical analyses and correlated with the photovoltaic parameters. Interestingly, core-shell CdS NWs/ Ag₂S exhibits 1.5 better performance in terms of linear voltammetry, photocurrent transient response and the photo stability than bare CdS. Furthermore, three-fold enhancement in photoelectrochemical conversion efficiency have been observed for optimized FTO/ CdS NWs/Ag₂S compared to bare FTO/CdS NWs due to the augmented light harvesting and condensed charge recombination. External quantum efficiency exhibits 24% for the optimized CdS NWs/ Ag₂S core shell structure. Mott-Schottky and electrochemical impedance spectroscopy measurements have been used for better understanding the impact of gradual growth of Ag₂S over CdS NWs which directly influences the overall photocurrent density of the devices.

Photocatalytic Performance and Mechanism Research of Ag/HSTiO2 on Degradation of Methyl Orange

The Sol-gel method is successfully used to prepare high specific surface area TiO₂ (HSTiO₂). Then, the photodeposition method is used to composite silver particles with HSTiO₂. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller, and UV-vis spectroscopy are used to characterize the Ag/HSTiO₂ nanocomposites. It can be concluded that the prepared TiO₂ has a large specific surface area, reaching 125.5 m² g^-1. Additionally, the addition of silver particles successfully broadens the photoresponse range from the UV region to the visible light region. In order to evaluate the photocatalytic activity of Ag/HSTiO₂, we conducted the methyl orange degradation test. The results showed that the photocatalytic activity of the sample is significantly higher than that of pure TiO₂.

Synthesis of Ag-Doped Polyoxotitanium Nanoclusters for Efficient Electrocatalytic CO2 Reduction

Ag-Ti nanocomposite materials have drawn increasing research attention because of their superior catalytic properties. However, the preparation of a crystalline Ag-Ti material is an important challenge in synthetic chemistry. Herein, we report a family of atomically precise Ag-doped polyoxotitanium nanoclusters (PTCs) (PTC-253-PTC-256) with a size of 19.56 × 19.02 Å. Each Ag-PTC is made up of a tiny Ag₂ kernel and a double-decker Ti₁₂ nanowheel as well as an organic protective shell. Hence, they can be regarded as Ag₂@Ti₁₂@(L)₁₄(OMe)_n unique triple core-shell structures. Notably, the peripheral organic shell can be modified with different benzoate derivatives. With precise atomic information, these compounds can be used as ideal molecular models of Ag-Ti nanocomposite materials for studying the growth or reaction mechanism via theoretical calculations. Meanwhile, a PTC-255-modified electrode presents efficient electrocatalytic CO₂ reduction activity with a Faradaic efficiency (FE) of 29.4%. This work demonstrates that Ag-doped crystalline PTC materials are promising candidates for application to the electrocatalytic CO₂ reduction reaction (CO₂RR).

In situ growth of metallic Ag0 intercalated CoAl layered double hydroxides as efficient electrocatalysts for the oxygen reduction reaction in alkaline solutions

Metallic Ag⁰ intercalated CoAl LDHs synthesized via a facile redox process exhibited excellent ORR activity through a four-electron reduction process.

Highly Efficient, Low-Cost, and Magnetically Recoverable FePt⁻Ag Nanocatalysts: Towards Green Reduction of Organic Dyes

Nowadays, synthetic organic dyes and pigments discharged from numerous industries are causing unprecedentedly severe water environmental pollution, and conventional water treatment processes are hindered due to the corresponding sophisticated aromatic structures, hydrophilic nature, and high stability against light, temperature, etc. Herein, we report an efficient fabrication strategy to develop a new type of highly efficient, low-cost, and magnetically recoverable nanocatalyst, i.e., FePt⁻Ag nanocomposites, for the reduction of methyl orange (MO) and rhodamine B (RhB), by a facile seed deposition process. X-ray diffraction results elaborate that the as-synthesized FePt⁻Ag nanocomposites are pure disordered face-centered cubic phase. Transmission electron microscopy studies demonstrate that the amount of Ag seeds deposited onto the surfaces of FePt nanocrystals increases when increasing the additive amount of silver colloids. The linear correlation of the MO and RhB concentration versus reaction time catalyzed by FePt⁻Ag nanocatalysts is in line with pseudo-first-order kinetics. The reduction rate constants of MO and RhB increase with the increase of the amount of Ag seeds. FePt⁻Ag nanocomposites show good separation ability and reusability, and could be repeatedly applied for nearly complete reduction of MO and RhB for at least six successive cycles. Such cost-effective and recyclable nanocatalysts provide a new material family for use in environmental protection applications.

Face-to-Face Interfacial Assembly of Ultrathin g-C3N4 and Anatase TiO2 Nanosheets for Enhanced Solar Photocatalytic Activity

Face-to-face interfacial assembly of TiO₂-g-C₃N₄ hybrid (2D TCN-A) is developed by surfactant-assisted hydrothermal treatment forming a sandwich structure of anatase TiO₂ nanosheets (TiO₂-A, 5-6 monolayers) and g-C₃N₄ nanosheets (∼3 monolayers). Post air-annealing is found effective for insertion of oxygen to the hybrid, which remedies the oxygen vacancies of TiO₂ (B) nanosheets and converts it to anatase nanosheets. The enhanced light adsorption, increased donor density, and prolonged life of charge carries are achieved by variation of bandgap and the formation of heterojuction between the two kinds of nanosheets, facilitating separation and transfer of charge carriers. The 2D TCN-A-70 nanosheets show a high photodegradation rate of methyl orange (k_app ≈ 0.189 min^-1) and photocatalytic evolution rate of hydrogen (18200 μmol g^-1 h^-1). This 2D nanosheets hybrid is potentially useful in alleviating environmental and energy issues.

Sequential Process Combination of Photocatalytic Oxidation and Dark Reduction for the Removal of Organic Pollutants and Cr(VI) using Ag/TiO2

We investigated a sequential photocatalysis-dark reaction, wherein organic pollutants were degraded on Ag/TiO₂ under UV irradiation and the dark reduction of hexavalent chromium (Cr(VI)) was subsequently followed. The photocatalytic oxidation of 4-chlorophenol (4-CP), a test organic substrate, induced the generation of degradation intermediates and the storage of electrons in Ag/TiO₂ which were then utilized for reducing Cr(VI) in the postirradiation period. The dark reduction efficiency of Cr(VI) was much higher with Ag/TiO₂ (87%), compared with bare TiO₂ (27%) and Pt/TiO₂ (22%). The Cr(VI) removal by Ag/TiO₂ (87%) was contributed by adsorption (31%), chemical reduction by intermediates of 4-CP degradation (26%), and reduction by electrons stored in Ag (30%). When formic acid, humic acid or ethanol was used as an alternative organic substrate, the electron storage effect was also observed. The postirradiation removal of Cr(VI) on Ag/TiO₂ continued for hours, which is consistent with the observation that a residual potential persisted on the Ag/TiO₂ electrode in the dark whereas little residual potential was observed on bare TiO₂ and Pt/TiO₂ electrodes. The stored electrons in Ag/TiO₂ and their transfer to Cr(VI) were also indicated by the UV-visible absorption spectral change. Moreover, the electrons stored in the preirradiated Ag/TiO₂ reacted with O₂ with showing a sign of low-level OH radical generation in the dark period.

Enhanced photocatalysts based on Ag-TiO2 and Ag-N-TiO2 nanoparticles for multifunctional leather surface coating

The Ag deposition on TiO2 nanoparticles (Ag-TiO2 NPs) and N-TiO2 nanoparticles (Ag-N-TiO2 NPs) has been made by electrochemical methodology in view of improved antibacterial properties and enhanced photocatalytic activity under visible light irradiation. The particle size in powder and in dispersion showed similar values and good stability in aqueous medium which made them suitable for use in leather surface covering for new multifunctional properties development. The diffuse reflectance spectra of Ag-TiO2 NPs, Ag-N-TiO2 NPs and TiO2 NPs have been investigated and correlated with their photocatalytic performances under UV and visible light against different silver concentrations. The leather surfaces treated with Ag-N-TiO2 NPs showed advanced self-cleaning properties under visible light exposure through the hydrophilic mechanism of organic soil decomposition. Moreover the bacterial sensitivity and proven fungitoxic properties of Ag-N-TiO2 NPs leads to the possibility of designing new multifunctional additives to extend the advanced applications for more durable and useable materials.

Synthesis, characterization and antibacterial activity of Ag incorporated ZnO–graphene nanocomposites

One pot low temperature synthesis of silver incorporated ZnO–chemically converted graphene nanocomposites is reported. An optimum of 10% Ag incorporated sample at 6.25 μg ml⁻¹ dose shows an excellent antibacterial activity on E. coli and S. aureus.

Improving photocatalytic performance of ZnO via synergistic effects of Ag nanoparticles and graphene quantum dots

A Ag–graphene quantum dots (GQDs)–ZnO ternary photocatalyst was prepared using GQDs as both a reducing agent and a cation solvent. Photodegradation performance was improved because of the synergic effect of Ag and GQDs.