Ag-Ag2O decorated multi-walled carbon nanotubes/NiCoAl hydrotalcite sensor for trace nitrite quantification.

Ag-Ag2O-decorated multiwall carbon nanotube/NiCoAl-hydrotalcite (CNT/LDH-Ag) composites were designed and synthesized for nitrite quantification. The materials were characterized by various techniques, and their electrochemical NO2- detection performances investigated using amperometric and differential pulse voltammetry (DPV) techniques. The Ag-Ag2O nanoparticles (NPs) were anchored on the surface of the CNT/LDH-Ag composites. At a suitable amount of the Ag-Ag2O loading, the Ag-Ag2O NPs with small particle size were distributed evenly on the CNT/LDH surface, increasing the surface area of the composites. The optimal CNT/LDH-Ag3 composite exhibited a high electrochemical activity for NO2- oxidation in pH 7.0. Furthermore, the optimal CNT/LDH-Ag3 composite was fabricated for trace NO2- quantification. The proposed sensor displayed a high sensitivity (0.0960 µA·µM-1·cm-2) and fast response (< 3 s) toward NO2- in a wide linear range from 0.250 µmol·L-1 to 4.00 mmol·L-1 with a low detection limit of 0.0590 µmol·L-1(S/N = 3). The sensor provided an outstanding analytical performance with a desirable recovery (95.3 ~ 107%, RSD < 1.05%) in real sample. As a result, the proposed sensor can be used for the real-time quantification of trace NO2- in the biological, food, and environmental fields.

Novel SERS biosensor for rapid detection of breast cancer based on Ag2O-Ag-PSi nanochips.

Ag2O-Ag-PSi (porous silicon) surface-enhanced Raman scattering (SERS) chip was successfully synthesized by electrochemical corrosion, in situ reduction and heat treatment technology. The influence of different heat treatment temperature on SERS performance of the chip is studied. The results show that the chip treated at 300 °C has the best SERS performance. The chip was composed of Ag2O-Ag nano core shell with a diameter of 40-60 nm and porous silicon substrate. Then, the optimized chip was used to perform SERS test on serum samples from 30 healthy volunteers and 30 early breast cancer patients, and the baseline was corrected by LabSpec6 software. Finally, the data were analyzed by principal component analysis combined with t-distributed Stochastic Neighbor Embedding (PCA-t-SNE). The results showed that the accuracy of the improved substrate combined with multivariate statistical method was 98%. The shelf life of the chips exceeded six months due to the presence of the Ag2O shell. This study provides a basis for developing a low-cost rapid and sensitive early screening technology for breast cancer.

Ag2S-Ag2O-Ag/poly-2-aminobenzene-1-thiol Nanocomposite as a Promising Two-Electrode Symmetric Supercapacitor: Tested in Acidic and Basic Mediums.

A Ag2S-Ag2O-Ag/poly-2-aminobenzene-1-thiol (P2ABT) nanocomposite was prepared using the photopolymerization reaction using AgNO3 as an oxidant. The size of the nanocomposite was about 40 nm, in which the morphology was confirmed using TEM and SEM analyses. The functional groups of Ag2S-Ag2O-Ag/P2ABT were confirmed using FTIR; also, XRD confirmed the inorganic Ag2S, Ag, and Ag2O formation. This nanocomposite has great performance in supercapacitor applications, with it tested in acidic (1.0 M HCl) and basic mediums (1.0 M NaOH). This pseudo-capacitor has great performance that appeared through the charge time in an acid medium in comparison to the basic medium with values of 118 s and 103 s, correspondingly. The cyclic voltammetry (CV) analysis further confirmed the excellent performance of the supercapacitor material, as indicated by the large area under the cyclic curve. The specific capacitance (CS) and energy density (E) values (at 0.3 A/g) were 92.5 and 44.4 F/g and 5.0 and 2.52 W·h·Kg-1 in the acidic and basic mediums, correspondingly. The charge transfer was studied through a Nyquist plot, and the produced Rs values were 4.9 and 6.2 Ω, respectively. Building on these findings, our objective is to make a significant contribution to the progress of supercapacitor technology through a prototype design soon.

Fabrication of optimal oxygen vacancy amount in P/Ag/Ag2O/Ag3PO4/TiO2 through a green photoreduction process for sustainable H2 evolution under solar light.

Defects engineering on photocatalysts such as oxygen vacancies (OVs) is an effective approach for improving photocatalytic hydrogen (H2) evolution efficiency. In this study, OVs modified P/Ag/Ag2O/Ag3PO4/TiO2 (PAgT) composite was successfully fabricated via a photoreduction process by controlling the ratio of PAgT to ethanol (16, 12, 8, 6 and 4 g·L-1) under simulated solar light irradiation for the first time. Characterization methods confirmed the presence of OVs in the modified catalysts. Meanwhile, the OVs amount and their effects on the light absorption ability, charge transfer rate, conduction band and H2 evolution efficiency of the catalysts were also investigated. The results indicated that the optimal OVs amount endowed OVs-PAgT-12 with the strongest light absorption, the fastest electron transfer rate and suitable band gap for H2 evolution, leading to the highest H2 yield (863 µmol·h-1·g-1) under solar light irradiation. Moreover, OVs-PAgT-12 exhibited a superior stability during cyclic experiment, indicating its great potential for practical application. Furthermore, a sustainable H2 evolution process was proposed based on a combination of sustainable bio-ethanol resource, stable OVs-PAgT, abundant solar energy and recyclable methanol. This study would provide new insights into the design of defects modified composite photocatalyst for enhanced solar-to-hydrogen conversion.

Polyethylene glycol (PEG)-modified Ag/Ag2O/Ag3PO4/Bi2WO6 photocatalyst film with enhanced efficiency and stability under solar light.

Bi2WO6 photocatalyst possesses great photocatalytic properties, modification with Ag, Ag2O, and Ag3PO4 further improve its photocatalytic activity. Photocatalyst utilized as suspended powders in wastewater treatment imposes restrictions for practical application. Therefore, the design and fabrication of photocatalyst film with high efficiency and stability are crucial for practical application. In this study, polyethylene glycol (PEG) modified AP-BWO (A: Ag, Ag2O; P: Ag3PO4; BWO: Bi2WO6) photocatalyst film coated on glass substrate was firstly synthesized with excellent photocatalytic activity and stability. Bi2WO6based films were modified with different PEG molecular weight, dosage and coating layers, followed by characteristic analysis (SEM, TEM, XPS, UVvis, PL, and photocurrent density) and photodegradation test. Photodegradation showed that 2-layered of 12 g L-1 PEG2000 modified AP-BWO film exhibited the highest photocatalytic activity. XPS and TEM indicated that PEG2000-AP-BWO film was fabricated successfully. SEM and UV-vis denoted the photocatalyst film showed small particle size and strong visible-light absorption. Furthermore, PL and photocurrent density confirmed its low recombination and fast charge separation of electronhole pairs. The photocatalytic films showed high activity and stability in both 10-cycle repeatability experiments and tandem-type photocatalytic recycle system. Therefore, PEG2000-AP-BWO film with enhanced photocatalytic performance and stability was a promising alternative for wastewater treatment.

Nanometer mixed-valence silver oxide enhancing adsorption of ZIF-8 for removal of iodide in solution.

Nano mixed-valence silver oxide (Ag2O-Ag2O3) modified the zeolitic imidazolate framework-8 (ZIF-8) composite (Ag2O-Ag2O3@ZIF-8) was firstly prepared via a simple and efficient method, characterized and applied for iodide ion (I-) uptake from simulated radioactive wastewater. The results showed that Ag2O-Ag2O3 nanoparticles doped and uniformly dispersed on the surface of ZIF-8 matrix. The adsorption capacity of the as-synthesized adsorbents increased with the increasing Ag doped amount, and the maximum adsorption capacity for 20%-Ag2O-Ag2O3@ZIF-8 was 232.12 mg/g. The calculated thermodynamic parameters indicating that the adsorption was a spontaneous and exothermic. It was worth mentioning that each Ag-based adsorbent exhibited high uptake rate of I-, and all the adsorption tests were equilibrated for a few minutes. This could be ascribed to its large specific surface area and the absolutely dominant position of chemical adsorption for as-prepared samples. Furthermore, the adsorption was barely affected by pH and competitive anions (e.g. Cl-, SO42-, CO32-), even in simulated salt lake water. Additionally, a mechanism explaining the excellent properties for adsorbents could be epitomized into three aspects, namely, the uptake performance of Ag2O for I-, the strong oxidization of Ag2O3 for I-, and the adsorption of AgI for I2.

Superior disinfection effect of Escherichia coli by hydrothermal synthesized TiO2-based composite photocatalyst under LED irradiation: Influence of environmental factors and disinfection mechanism.

The photocatalytic inactivation of Escherichia coli (E. coli) under light-emitting diode (LED) light irradiation was performed with P/Ag/Ag2O/Ag3PO4/TiO2 photocatalyst to investigate the photocatalytic bactericidal activity. Our work showed that this composite photocatalyst possessed remarkable bacterial disinfection ability and could completely inactivate 108 cfu/mL of E. coli within just 40 min under the optimum catalyst loading of 0.5 g/L. The effects of different environmental factors, including light wavelength, light intensity, temperature, solution pH and inorganic ions, on the inactivation efficiency were evaluated. The results showed that bacteria inactivation by P/Ag/Ag2O/Ag3PO4/TiO2 was more favorable with blue colored LED irradiation, light intensity at 750 W/m2, temperature in the range of 30-37 °C and pH values at natural or slightly alkaline condition. The existence of different inorganic ions under normal environmental level had no significant impact on the bactericidal performance. In addition, during the inactivation process, the morphology changes of E. coli cells were directly observed by scanning electron microscope (SEM) and further proved by the measurement of K+ leakage from the inactivated E. coli. The results demonstrated that the photocatalytic inactivation caused drastic damage on bacterial cells membrane. Furthermore, the mechanisms of photocatalytic bacterial inactivation were also systemically studied and the results confirmed that the excellent disinfection activity of P/Ag/Ag2O/Ag3PO4/TiO2 resulted from the major reactive species: h+ and ·O2- from photocatalytic process instead of the leakage of Ag+ (≤0.085 ±â€¯0.005 mg/L) from photocatalyst. These results indicate that P/Ag/Ag2O/Ag3PO4/TiO2 photocatalyst has promising potential for real water sterilization application.

Dispersed Ag2O/Ag on CNT-Graphene Composite: An Implication for Magnificent Photoreduction and Energy Storage Applications.

A simple hydrothermal route assisted by a triblock copolymer was used to synthesize Ag2O/Ag nanoparticles on a robotic support consists of functionalized MWCNTs and graphene composite (Ag2O/Ag/CNT-graphene). The composites together with the individual analog of Ag/CNT and Ag/graphene were characterized by means of XRD, TEM-SAED, N2 sorptiometry, Raman, FTIR, UV-Vis, and photoluminescence spectroscopy. These nanomaterials were then tested for the catalytic reduction of 4-nitrophenol (4-NP) to the technologically beneficial 4-aminophenol (4-AP). The Ag2O@Ag@CNT-graphene composite calcined at 400°C has shown fascinating reduction performances for 4-NP either in the dark (k = 0.014 s-1) or under visible light illumination (k = 0.039 s-1) in the presence of 5 mM NaBH4 compared to Ag/CNT (0.0112 s-1) and Ag/graphene (0.010 s-1) catalysts. This was chiefly because Ag2O@Ag@CNT-graphene comprises the highest pore volume (0.49 cm3/g) and involves three types of pores in the margin from 1.8 to 4.0 nm in front of only one modal type of pores for the rest of the catalysts and thus maximizes the adsorptive capacity of the reactants (4-NP and NaBH4). Moreover, the former composite exhibits the highest concentration of the Ag2O component as established by numerous techniques in addition to the cyclic voltammetry, proposing it's facile reaction with 4-NP along with the simultaneous transfer of surface hydrogen and electrons from NaBH4 ions to produce 4-AP. The promotion of the p-n junction evaluated using the Mott-schottky equation on Ag2O@Ag@CNT-graphene assisted by charges separation and surface plasmon resonance bands of Ag and Ag2O are found to be advantageous for 4-NP reduction. The latter composite delivers a specific capacitance of 355 F g-1 at 1.0 A g-1 exceeding those of Ag/CNT (230 F g-1) and Ag/graphene (185 F g-1). The EIS study establishes the high electronic conductivity of the metallic Ag and Ag2O moieties, low internal resistance of CNT-graphene as well as the marked ionic transfer facilitated by the composite porous nature.

A novel P/Ag/Ag2O/Ag3PO4/TiO2 composite film for water purification and antibacterial application under solar light irradiation.

TiO2-based thin films have been intensively studied in recent years to develop efficient photocatalyst films to degrade refractory organics and inactivate bacteria for wastewater treatment. In the present work, P/Ag/Ag2O/Ag3PO4/TiO2 composite films on the inner-surface of glass tube were successfully prepared via sol-gel approach. P/Ag/Ag2O/Ag3PO4/TiO2 composite films with 3 coating layers, synthesized at 400°C for 2h, showed the optimal photocatalytic performance for rhodamine B (Rh B) degradation. The results indicated that degradation ratio of Rh B by P/Ag/Ag2O/Ag3PO4/TiO2 composite film reached 99.9% after 60min under simulated solar light, while just 67.9% of Rh B was degraded by pure TiO2 film. Moreover, repeatability experiments indicated that even after five recycling runs, the photodegradation ratio of Rh B over composite film maintained at 99.9%, demonstrating its high stability. Photocatalytic inactivation of E. coli with initial concentration of 107CFU/mL also showed around 100% of sterilization ratio under simulated solar light irradiation in 5min by the composite film. The radical trapping experiments implied that the major active species of P/Ag/Ag2O/Ag3PO4/TiO2 composite films were photo-generated holes and O2- radicals. The proposed photocatalytic mechanism shows that the transfer of photo-induced electrons and holes may reduce the recombination efficiency of electron-hole pairs and potential photodecomposition of composite film, resulting in enhanced photocatalytic ability of P/Ag/Ag2O/Ag3PO4/TiO2 composite films.

Recoverable hybrid enzymatic biofuel cell with molecular oxygen-independence.

Enzymatic biofuel cells (EBFCs) have drawn great attentions because of its potential in energy conversion. However, designing of highly efficient EBFCs which can adapt to the anaerobic system is still a great challenge. In this study, we propose a novel hybrid enzymatic biofuel cell (HEBFC) which was fabricated by a glucose dehydrogenase modified bioanode and a solid-state silver oxide/silver (Ag2O/Ag) cathode. The as-assembled HEBFC exhibited an open circuit potential of 0.59V and a maximum power output of 0.281mWcm(-2) at 0.34V in air saturated buffer. Especially, due to the introduction of Ag2O/Ag, our HEBFC could also operate under anaerobic condition, while the maximum power output would reach to 0.275mWcm(-2) at 0.34V. Furthermore, our HEBFC had stable cycle operation and could keep high power output for a certain time as the result of the regeneration of Ag2O. Our work provides a new concept to develop EBFCs for efficient energy conversion in the future.

Efficient removal of radioactive iodide ions from water by three-dimensional Ag2O-Ag/TiO2 composites under visible light irradiation.

Three-dimensional Ag2O and Ag co-loaded TiO2 (3D Ag2O-Ag/TiO2) composites have been synthesized through a facile method, characterized using SEM, EDX, TEM, XRD, XPS, UV-vis DRS, BET techniques, and applied to remove radioactive iodide ions (I(-)). The photocatalytic adsorption capacity (207.6 mg/g) of the 3D Ag2O-Ag/TiO2 spheres under visible light is four times higher than that in the dark, which is barely affected by other ions, even in simulated salt lake water where the concentration of Cl(-) is up to 590 times that of I(-). The capability of the composites to remove even trace amounts of I(-) from different types of water, e.g., deionized or salt lake water, is demonstrated. The composites also feature good reusability, as they were separated after photocatalytic adsorption and still performed well after a simple regeneration. Furthermore, a mechanism explaining the highly efficient removal of radioactive I(-) has been proposed according to characterization analyses of the composites after adsorption and subsequently been verified by adsorption and desorption experiments. The proposed cooperative effects mechanism considers the interplay of three different phenomena, namely, the adsorption performance of Ag2O for I(-), the photocatalytic ability of Ag/TiO2 for oxidation of I(-), and the readsorption performance of AgI for I2.