Photoreduction Method Research Articles

Ag enhanced CuS nanoflower catalyst coupling dielectric barrier discharge plasma for disinfection performance and mechanism

In this study, the hydrothermal method was employed to grow submicron CuS on carbon cloth (CC), and the photoreduction method was used to grow Ag nanoparticles on the CuS submicron flowers, thus forming the Ag/CuS/CC catalytic electrode. The application of Ag/CuS/CC electrode-coupled dielectric barrier discharge (DBD) plasma in the disinfection of pathogenic bacteria in water was studied. The Ag/CuS/CC electrode exhibits strong antibacterial activity, and under an external voltage of 30 V, the degradation efficiency of Bacillus subtilis reaches 99.99% within 15 min without regeneration. After five cycles, the inactivation rate of Bacillus subtilis reached 99.99% within 25 min. The practical applicability of the Ag/CuS/CC-coupled DBD system for treating actual wastewater was evaluated, and the changes in biological toxicity were investigated. The results indicate that the prepared Ag/CuS/CC coupled DBD has great potential for safe disinfection of pathogenic bacteria in water through integrated processes.

Synthesis of gold nanoparticles using soybean byproducts: applications in catalysis

AbstractThis study demonstrates the feasibility of extracting lecithin from oil industry byproducts in an eco‐friendly manner, with minimal use of water and without harmful chemicals. Liposomes can be generated directly from this extracted lecithin, enhancing the value of these byproducts and enabling the production of catalytic gold nanoparticles (AuNPs). Thin‐layer chromatography of the extracted lecithin revealed a phospholipid composition primarily consisting of phosphatidylethanolamine and phosphatidylcholine, and surface tension studies demonstrated similar behavior between the extracted and commercial lecithin. Liposome formation using sustainable lecithin (LPn) resulted in structures that were stable for at least 10 days, exhibiting a low polydispersity index (0.395) and uniform size (approximately 214 ± 7 nm). Gold nanoparticles were synthesized successfully in LPn loaded with [HAuCl4] by using different photoreduction methods: ultraviolet (UV) lamp, pulsed laser 355 nm, and sunlight irradiation. The AuNPs exhibited characteristic sizes (ranging from 5.03 to 6.78 nm) and optical properties typical of nanoparticles, including a distinct surface plasmon resonance. As a proof of concept, we also demonstrated that the synthesized AuNPs exhibited catalytic activity in UV‐induced cis‐trans isomerization reactions. Overall, the study highlights the potential of sustainable soy lecithin extraction for diverse applications, including nanoparticle synthesis and catalysis.

A HOF-101@AgNPs-based dual-signal mode aptasensor for electrochemiluminescence and fluorescence detection of E. coli O157:H7

Escherichia coli O157:H7 (E. coli O157:H7) emerges as a foodborne pathogen, emphasizing the imperative for creating precise detection tools. An ultrasensitive electrochemiluminescence/fluorescence (ECL/FL) dual-signal mode aptasensor was constructed for the detection of E. coli O157:H7. Ultrafine silver nanoparticles were loaded on the surface of hydrogen-bonded organic skeleton materials by in-situ photoreduction method, and then combined with aptamers that can identify specific targets to prepare HOF-101@AgNPs@Apt, greatly simplifying the ECL/FL dual-signal mode probe fabrication process and improving sensing reliability. HOF-101@AgNPs@Apt had both strong ECL luminescence and fluorescence, resulting in a high detection sensitivity. The low limit of detection (LOD) for ECL and FL were 0.48 CFU mL−1 and 2.39 CFU mL−1, respectively. Moreover, the proposed dual-signal mode aptasensor has been successfully applied to determine E. coli O157:H7 levels in tap water and milk with superior accuracy and high antiinterference capability, providing a promising method for food safety monitoring.

Constructing AlOOH-PVA/ZIF-67/AgCl/Ag composite membrane for the efficient photodegradation of organic pollutants under visible light irradiation

This study effectively fabricated photocatalytic membranes (∼5 cm diameter) assembled by γ-AlOOH-PVA (BOP) decorated heterostructural ZIF-67/AgCl/Ag composites by combing seeded secondary growth and photoreduction methods. First, the ZIF-67-seeded BOP membrane was shaped in a petri dish, followed by submerging in a 2-methylimidazole ligand for secondary growth to obtain the BOP/ZIF-67 membrane. Next, AgCl/Ag was formulated on the membrane by dipping it in an AgNO3 solution, followed by a photoreduction under visible LED light, resulting in a BOP/ZIF/AgCl/Ag membrane. The characterization showed that the membrane contained heterostructures of ZIF-67/AgCl/Ag anchored onto the BOP membrane. The BOP/ZIF/AgCl/Ag composite membranes exhibited enhanced light absorption and appeared the localized surface plasmon resonance (LSPR) of Ag0, giving it a bandgap energy of ∼2.10 eV. Photodegradation under visible LED light irradiation showed that the BOP/ZIF/AgCl/Ag membrane efficiently removed tetracycline (TC) and Rhodamine B dye (RhB) with corresponding degradation efficiency of ∼99% (90 min) and ∼95% (140 min), giving reaction rates of ∼0.046 min−1 and 0.019 min−1, respectively. The photocatalytic mechanism and photodegradation pathways analyses provided insights into the degradations of organic pollutants. Significantly, the designed BOP/ZIF/AgCl/Ag membrane quickly recovered from the solution and was of good durability. The study provided an effective strategy for constructing heterostructural ZIF-67/AgCl/Ag composite membranes, which are efficient and eco-friendly photocatalyst materials.

Integration of Silver Nanoparticles into Carbon-Encapsulated Tungsten Oxide Promoting Visible-Light-Driven Photocatalytic Degradation Efficiency

WO3-based photocatalysts have garnered popularity due to their low cost and high stability. However, the strong photogenerated electron-hole recombination limits their practical applicability. Herein, we developed an innovative heterostructure that integrates silver nanoparticles (Ag NPs) into carbon-encapsulated WO3 (C-WO3) through a combination of solvothermal synthesis and photoreduction methods. Under visible light irradiation, the Ag/C-WO3 photocatalyst demonstrated significant photocatalytic activity for rhodamine B (RhB) degradation, and the fine-tuned Ag/C-WO3 photocatalyst possesses excellent RhB degradation performance, achieving a removal rate of 98.2 % with excellent photostability. The photocatalytic process follows first-order kinetics, with adsorbent diffusion identified as the rate-limiting step. The optimized Ag/C-WO3 had an apparent rate constant of 0.039 min−1, 9.75 times higher than that of the unmodified C-WO3 (0.004 min−1). The enhanced photocatalytic activity is primarily owing to the surface plasmon resonance effect of Ag NP, which increases the absorption of visible light and boosts electron generation. Additionally, the carbon layer that encapsulates WO3 serves as a bridge for electron transfer from Ag to WO3, thereby accelerating the separation of photogenerated electron-hole pairs and elevating the overall photocatalytic degradation efficiency. The Ag NP-decorated C-WO3 with superior degradation properties is expected to be a potential candidate in practical and industrial applications.

Near-infrared light-enhanced colorimetric signal amplification strategy for tumor marker detection based on MoS2/CuO/Au nanocomposite.

Anovel signal amplification strategy was developedby combining near-infrared light with MoS2/CuO/Au nanocomposite for building acolorimetric immunoassay. First, MoS2/CuO/Au nanocomposite was synthesized by precipitation and photoreduction methods and characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). MoS2/CuO/Au nanocomposite has oxidase-like activity and can oxidize TMB to form a blue product (TMBox). Further, the catalytic oxidation of TMB was accelerated under near-infrared (NIR) laser radiation. The sandwich-type colorimetric immunoassay was constructed using MoS2/CuO/Au nanocomposite. Under the enhancement of near-infrared light, carcinoembryonic antigen (CEA) was sensitively detected in the range 0.1 to 40ng/mL with the limit of detection of 0.03ng/mL. Moreover, the immunosensor has excellent selectivity and anti-interference, good repeatability, and stability.

Plasmon-Enhanced Light Absorption Below the Bandgap of Semiconducting SnS2 Microcubes for Highly Efficient Solar Water Evaporation.

Semiconducting materials show high potential for solar energy harvesting due to their suitable bandgaps, which allow the efficient utilization of light energy larger than their bandgaps. However, the photon energy smaller than their bandgap is almost unused, which significantly limits their efficient applications. Herein, plasmonic Pd/SnS2 microcubes with abundant Pd nanoparticles attached to the SnS2 nanosheets are fabricated by an in situ photoreduction method. The as-prepared Pd/SnS2 microcubes extend the light-harvesting ability of SnS2 beyond its cutoff wavelength, which is attributed to the localized surface plasmon resonance (LSPR) effect of the Pd nanoparticles and the 3D structure of the SnS2 microcubes. Pd nanoparticles can also enhance the light absorption of TiO2 nanoparticles and NiPS3 nanosheets beyond their cutoff wavelengths, revealing the universality for promoting absorption above the cutoff wavelength of the semiconductors. When the plasmonic Pd/SnS2 microcubes are integrated into a hydrophilic sponge acting as the solar evaporator, a solar-to-vapor efficiency of up to 89.2% can be achieved under one sun. The high solar-to-vapor conversion efficiency and the broad applicability of extending the light absorption far beyond the cutoff wavelength of the semiconductor comprise the potential of innovative plasmonic nanoparticle/semiconductor composites for solar desalination.

Identification of quantitative trait loci and candidate genes for grain superoxide dismutase activity in wheat

BackgroundSuperoxide dismutase (SOD) can greatly scavenge reactive oxygen species (ROS) in plants. SOD activity is highly related to plant stress tolerance that can be improved by overexpression of SOD genes. Identification of SOD activity-related loci and potential candidate genes is essential for improvement of grain quality in wheat breeding. However, the loci and candidate genes for relating SOD in wheat grains are largely unknown. In the present study, grain SOD activities of 309 recombinant inbred lines (RILs) derived from the ‘Berkut’ × ‘Worrakatta’ cross were assayed by photoreduction method with nitro-blue tetrazolium (NBT) in four environments. Quantitative trait loci (QTL) of SOD activity were identified using inclusive composite interval mapping (ICIM) with the genotypic data of 50 K single nucleotide polymorphism (SNP) array.ResultsSix QTL for SOD activity were mapped on chromosomes 1BL, 4DS, 5AL (2), and 5DL (2), respectively, explaining 2.2 ~ 7.4% of the phenotypic variances. Moreover, QSOD.xjau-1BL, QSOD.xjau-4DS, QSOD.xjau-5 A.1, QSOD.xjau-5 A.2, and QSOD.xjau-5DL.2 identified are likely to be new loci for SOD activity. Four candidate genes TraesCS4D01G059500, TraesCS5A01G371600, TraesCS5D01G299900, TraesCS5D01G343100LC, were identified for QSOD.xjau-4DS, QSOD.xjau-5AL.1, and QSOD.xjau-5DL.1 (2), respectively, including three SOD genes and a gene associated with SOD activity. Based on genetic effect analysis, this can be used to identify desirable alleles and excellent allele variations in wheat cultivars.ConclusionThese candidate genes are annotated for promoting SOD production and inhibiting the accumulation of ROS during plant growth. Therefore, lines with high SOD activity identified in this study may be preferred for future wheat breeding.

Photochemical synthesis of hierarchical adsorbents for gaseous iodine capture and storage

Developing rapid, cleaner synthesis strategies for adsorbent preparation through preparative chemistry, and elucidating pore and metal adsorption mechanisms, represent essential goals in achieving highly efficient capture and storage of radioactive iodine in the nuclear industry. This work utilizes solvent-free photopolymerization and one-step photoreduction methods to synthesize hierarchical zeolite Silicaite-1 (denoted as MS-1) and copper-modified zeolite Cu@MS-1, respectively. Focusing on the effects of metal species and pore structure on adsorption performance and mechanisms, their application to radioactive iodine sequestration from spent fuel is evaluated. The findings show adsorption of gaseous iodine by hierarchical zeolite MS-1 is predominantly physical. At 75 °C, it rapidly reaches high equilibrium adsorption capacity (524 mg/g) within 40 min, with faster iodine uptake kinetics than fully microporous zeolites and higher capacity than fully mesoporous silica. Introduction of metallic copper contributes additional chemical adsorption, efficaciously enhancing the MS-1 affinity for gaseous iodine. Cu@MS-1 achieves considerable equilibrium adsorption capacity (520 mg/g) in only 30 min, and improved radioactive iodine retention. The photochemical synthesis approach generates no liquid waste and forms the zeolite framework in 10 min. The obtained hierarchical zeolites MS-1 and Cu@MS-1 have high gaseous iodine capture and storage abilities, opening a new route for rapid and cleaner synthesis of highly efficient radioactive iodine adsorbents.

A novel photoreduction deposition induced AuNPs/COFs composite for SERS detection of macrolide antibiotics

As we all know, SERS (Surface-enhanced Raman spectroscopy) is widely used in sensing, analysis and detection. The covalent organic frameworks (COFs) have performed well as a material for supporting metal nanoparticles and facilitating analyte adsorption in SERS, which may greatly enhance the detection sensitivity and reproducibility. The synthesis of traditional metal/COFs composites involved chemical reduction methods, however, the resulting metallic NPs exhibited reduced capacity to enhance SERS due to their small particle sizes (usually <20 nm). This paper presented a novel photoreduction method for the facile growth of AuNPs (diameters: 75 nm) on COFs matrix under light control, which represents the first report of such synthesis on COF. Subsequently, the photoreduction deposition induced AuNPs/COFs composites, which served as highly sensitive and reproducible SERS-active substrates for capturing the spectral information of four types of macrolide antibiotics. The detection limits for the four macrolide antibiotics were determined to be 3.30 × 10−11, 3.43 × 10−10, 1.10 × 10−10 and 5.78 × 10−11 M, respectively, exhibiting excellent linear relationships within the concentration range of 10−10 to 10−3 M. Therefore, our proposed SERS method opens up a new idea for the development of SERS substrates and environmental safety monitoring, and it has great potential for ensuring food safety in the future.

Salt promoted metallic Pt photodeposition on graphitic carbon nitride towards efficiently photocatalytic hydrogen evolution

The photocatalytic hydrogen evolution (PHE) activity of pristine graphitic carbon nitride (GCN) and highly crystalline K+-doped GCN can significantly be enhanced under visible light irradiation via adding alkali metal salt into their PHE reaction solution. As manifested in XRD, UVDRS, TEM and XPS measurements, the loading amount of Pt cocatalyst on both GCN and K+-doped GCN, as well as the content of metallic Pt were greatly increased in the presence of 1.0 M KCl solution in the photoreduction solution. More significantly, the proportion of metallic Pt reached around 75 %. As a result, the PHE rate of K+-doped GCN was even as high as 11 mmol h–1g−1 under visible light irradiation. The current work offers a simple and cost-efficient strategy to promote the low depositing efficiency of Pt cocatalyst by traditional photoreduction method, thereby increasing the PHE activity of GCN and GCN based materials.

Influence of electrodeposition-dealloying and silver nanoparticles on the electrochemical properties of nanoporous NiO films for supercapacitor

Nanoporous NiO films are prepared by electrochemical dealloying the Zn-Ni alloys electrodeposited on Ni substrates followed by self-oxidizing method. The electrodeposition-dealloying parameters are investigated. The optimal nanoporous NiO film exhibits a specific capacitance of 1212.0 F/g at 1 A/g. The capacitance retention rate can reach 71.9 % at 20 A/g. The improved electrochemical properties are attributed to the hierarchical porous structure, which can provide large specific surface areas with enough exposed active sites and enhance the mass transport. On the basis of this, nanoporous NiO films are decorated with Ag nanoparticles with an average size of 50.6 nm using photoreduction method. Owing to the good ohmic contact between Ag and NiO, the nanoporous NiO-Ag films possess an increased specific capacitance up to 3592.9 F/g three times higher than the nanoporous NiO film. The capacitance retention rate reaches 84.5 % at 20 A/g. An asymmetric supercapacitor NiO-Ag//AC exhibits an energy density of 116.88 Wh/kg at 1720 W/kg. An energy density of 85.41 Wh/kg is maintained at 36600 W/kg. These boosted electrochemical performances are mainly owing to the synergistic effects of unique hierarchical porous structure and high electronic conductivity. This study provides a new approach to high performance electrodes for supercapacitors.

Fabrication of nano-dandelion magnetic TiO2/CuFe2O4 doped with silver as a highly visible-light-responsive photocatalyst for degradation of Naproxen and Rhodamine B

Nano-dandelion TiO2 and magnetic CuFe2O4 were synthesized with hydrothermal and sol–gel processes, respectively. A series of composites containing different amounts of CuFe2O4 and Ag were also prepared using a photoreduction method. The composites were subsequently used for photodegradation of Naproxen and Rhodamine B under UV–Vis light irradiation. The synthesized photocatalysts were characterized by XRD, FTIR, FESEM, EDX, TEM, BET-BJH, DRS, and PL analyses. XRD and FESEM results confirmed the successful synthesis of the dandelion structure for the composites. The VSM analysis also demonstrated the enhancement of magnetic properties of composites. DRS results indicated that CuFe2O4 loading and Ag doping resulted in a decrease in the band gap energy and enhanced absorption of light in the visible region as compared with pure TiO2. The presence of CuFe2O4 and Ag also increased charge transfer by decreasing electron-hole recombination rates by creating a Schottky-barrier interface which was indicated by the PL spectra. The composite containing 20% CuFe2O4 and 3% Ag (designated as TC20-3Ag) showed better performance as compared with other photocatalysts for photodegradation of Naproxen (92.56%) and Rhodamine B (91.16%) over a 150-minute reaction time. The sample also exhibited good stability after 5 cycles. The effects of operating parameters such as the pH of the solution, the photocatalyst dosage, and initial pollutant concentration were also investigated. It was found that a pseudo-first-order model adequately described the photodegradation kinetics. The results indicated that superoxide and holes were reactive species, and a possible mechanism for the photodegradation of Naproxen by TC20-3Ag was suggested.

Visible light driven mesoporous ag/Ag2CrO4/g-C3N4 degrades multiple organic pollutants efficiently: Synthesis, mechanism, and degradation pathway

With the development of economy, overuse of antibiotics has been seen as a huge threat to human health. Photocatalytic degradation is an effective method for resolving this problem at present. The method of combining plasmon resonance effect and Z-scheme heterojunction can effectively improve the separation efficiency of photogenerated carrier, which is of great significance for the treatment of antibiotic wastewater. Herein, the Ag/Ag2CrO4/g-C3N4 catalyst was prepared by in-situ loading and photo-reduction method for the degradation of antibiotic wastewater containing tetracycline and quinolone antibiotics. The research results showed that mesoporous graphitized carbon nitride (denoted as g-C3N4) provided good support for Ag and Ag2CrO4 nanoparticles, and mesoporous composite Ag/Ag2CrO4/g-C3N4 (denoted as ACO/CN) provided more reaction sites for organic pollutants degradation. Under visible light irradiation, 5%ACO/CN catalyst showed the best degradation activity and stability for tetracycline (TC), levofloxacin (LVFX), oxytetracycline hydrochloride (OTC) and norfloxacin (NFLX), and their degradation rate constants were respectively 5.66, 8.26, 11.72 and 15.97 times of Ag2CrO4 which indicated it had good potential application value in the treatment of wastewater containing various organic pollutants. This benefits from the plasmon resonance effect of silver effectively improves the utilization efficiency of visible light and the Z-scheme heterojunction between Ag2CrO4 and g-C3N4 promotes the rapid transmission of photogenerated carriers. Based on the experimental results, the possible TC degradation pathway and photocatalytic mechanism were proposed. This study provides a simple way for the successful design and preparation of plasmon resonance effect synergistic Z-scheme heterojunction with promising applications in the treatment of antibiotic wastewater.

Construction of highly active photocatalytic interfaces through light field modulation and photo-deposition of Pd sites

Anchoring noble metal sites through photo-reduction is an effective way to modulate charge distribution on photocatalytic interfaces, thereby enhancing photocatalytic performance. The irradiation field on the exposed surfaces of photocatalysts has an important influence on the morphology and distribution of noble metal sites. However, non-uniform light field derived from the scattering effects of particle-form photocatalysts hinders the well-distributed photo-deposition of noble metal sites. To address this challenge, we proposed a photo-deposition method utilizing the optical fiber coated with photocatalysts. TiO2 nanorod (NR) array was coated on the optical fiber to achieve a well-distributed irradiation filed across the NR array. This resulted in a concentration of the irradiation field primarily within the NR array, maintaining uniformly distributed light intensities throughout. Palladium (Pd) sites dominated by nanoclusters were well distributed on TiO2 NR array utilizing a photo-reduction method. These Pd sites functioned as electron acceptors, facilitating the effective separation and transfer of photo-generated carriers. Consequently, an highly active photocatalytic reaction interface was constructed, demonstrating the accumulation of a substantial concentration of holes and their efficient conversion into hydroxyl radicals (·OH). Notably, hydroxyl radicals with a concentration of 62.6 μM could be generated within 14.4 min. The construction of this efficient photocatalytic interface offers an optimal platform for accelerating photocatalytic reactions and enhancing photocatalytic efficiency.

Braided silk sutures coated with photoreduced silver nanoparticles for eradicating Staphylococcus aureus and Streptococcus mutans infections

BackgroundInfections resulting from surgical procedures and wound closures continue to pose significant challenges in healthcare settings. To address this issue, the investigators have developed antibacterial non-resorbable braided silk sutures using in situ deposited silver nanoparticles (AgNPs) and investigated their efficacy in eradicating Staphylococcus aureus and Streptococcus mutans infections. MethodsThe braided silk sutures were modified through a simple and efficient in situ photoreduction method, resulting in the uniform distribution of AgNPs along the suture surface. The synthesized AgNPs were characterized using scanning electron microscopy (SEM), dynamic light scattering analysis (DLS) and Fourier Transform Infrared Spectroscopy analysis (FTIR) confirming their successful integration onto the silk sutures. The antibacterial activity of the nanoparticle coated sutures were compared and evaluated with non-coated braided silk sutures through in vitro assays against both S. aureus and S. mutans. ResultsThe surface and cross-sectional analysis of the treated sutures revealed a uniform and homogeneous distribution of silver particles achieved through the photoreduction of silver solution. This observation confirms the successful coating of silver nanoparticles (AgNPs) on the sutures. The antimicrobial studies conducted, demonstrated significant reductions in bacterial colonies when exposed to the silver nanoparticle-coated sutures. Notably, the width of the inhibition zone surrounding the coated sutures remained consistently wide and stable for duration up to 7 days. This sustained and robust inhibitory effect against gram-positive bacteria, specifically S. aureus and S. mutans, serves as strong evidence of the antibacterial efficacy of the coated sutures. ConclusionThe coating of silk sutures with AgNPs provided a significant and effective antibacterial capacity to the surgical sutures, with this activity being sustained for a period of 7 days. This suggests that AgNPs-in situ photoreduction deposited sutures have the potential to effectively manage S. aureus and S. mutans infections.

Composite of formamidinium lead bromide perovskite FAPbBr3 with reduced graphene oxide (rGO) for efficient H2 evolution from HBr splitting

Solar hydrobromic acid (HBr) splitting using perovskite photocatalysts provides an attractive avenue to store solar energy into hydrogen (H2) and bromine (Br2), while an efficient photocatalytic system is still demanded. As for the semiconductor photocatalyst, formamidinium perovskites show some superiorities in structural stability, light adsorption and charge dynamics compared to their methylammonium counterparts, which are fitter for the photocatalysis process. Herein, the composite of formamidinium lead bromide perovskite (FAPbBr3) with reduced graphene oxide (rGO) is prepared using a facile photoreduction method. Under simulated sunlight irradiation (AM1.5G, 100 mW cm−2), this FAPbBr3/rGO composite (100 mg) demonstrates a noteworthy enhancement in photocatalytic H2 evolution activity of 386.7 μmol h−1, and it exhibits a notable stability with no significant decrease after 50 h of repeated tests. The single particle PL (photoluminescence) microscope is employed to study the charge dynamics, revealing that rGO in the composite effectively promotes the carrier separation. This work provides a highly efficient and stable photocatalyst for HBr splitting, and offers an effective modification strategy on lead bromide perovskites.

Boosting N[tbnd]N tri-bond activation and NH3 generation rate through simple surface Ag modification

NH3 photosynthesis from nitrogen remains a big challenge due to the extreme difficulty for the activation of NN bond. In this work, Ag-modified MoO3·0.55 H2O nanorods (named as Ag@Mo) are prepared by a simple photoreduction method. Under visible light (λ ≥ 420 nm) for 60 min, the NH3 yield over 2%Ag@Mo (molar ratio of Ag to MoO3·0.55 H2O) reaches 242.0 μmol·gcat−1, which is about 2.8 times higher than MoO3·0.55 H2O under the same conditions. The effect of Ag modification on photocatalytic ammonia synthesis is explored through experiments and theoretical calculations. The excellent photocatalytic performance is mainly attributed to the localized surface plasmon resonance effect of Ag and the successful construction of Mott-Schottky junction, which improves light utilization efficiency and reduces carrier recombination efficiency, respectively. Moreover, density functional theory calculations theoretically prove that over Ag@Mo, Ag provides new adsorption sites, and the NN tri-bond length is elongated by about 16.2%, confirming that Ag modification obviously promotes the activation of NN tri-bond. The ammonia generation rate is obviously higher than the previously reported results.

Silver dendrite metasurface SERS substrates prepared by photoreduction method for perfluorooctanoic acid detection

Perfluorooctanoic acid (PFOA), a novel organic pollutant, has been shown to be toxic, persistent, bioaccumulative, long-range transportable, and globally prevalent. This article is based on surface enhanced Raman scattering (SERS) spectroscopy analysis technology. The monolayer of SiO2 was prepared by chemical reduction etching self-assembly method and silver dendrites were grown on it, thus forming the SERS substrate with silver dendrite Metasurface structure with Raman detection enhancement factor up to 2.32 × 105. The prepared silver dendrite Metasurface SERS substrate was applied to the qualitative and quantitative detection of PFOA, with a quantitative detection limit of 15.89 ppb. The results of this paper provide a new, simple, and quick method for the detection of PFOA in the environment.

Visible light photocatalytic NOx removal with suppressed poisonous NO2 byproduct generation over simply synthesized triangular silver nanoparticles coupled with tin dioxide.

The treatment or conversion of air pollutants with a low generation of secondary toxic substances has become a hot topic in indoor air pollution abatement. Herein, we used triangle-shaped Ag nanoparticles coupled with SnO2 for efficient photocatalytic NO removal. Ag triangular nanoparticles (TNPs) were synthesized by the photoreduction method and SnO2 was coupled by a simple chemical impregnation process. The photocatalytic NO removal activity results show that the modification with Ag TNPs significantly boosted the removal performance up to 3.4 times higher than pristine SnO2. The underlying roles of Ag TNPs in NO removal activity improvement are due to some advantages of Ag TNPs. Moreover, the Ag TNPs contributed photogenerated holes as the main active species toward enhancing the NO oxidation reaction. In particular, the selectivity toward green products significantly improved from 52.78% (SnO2) to 86.99% (Ag TNPs/SnO2). The formation of reactive radicals under light irradiation was also verified by DMPO spin-trapping experiments. This work provides a potential candidate for visible-light photocatalytic NO removal with low toxic byproduct generation.