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Many strategies have been adopted to improve the photoinduced features of zinc oxide nanostructures for different application fields. In this work, zinc oxide has been synthesised and decorated by plasmonic metal nanoparticles to enhance its photocatalytic activity in the visible range. Furthermore, an insulating layer of SiO2 has been grown between the surface of zinc oxide nanoflakes and silver nanoparticles. A synthetic procedure that allows the accurate modulation of the insulating layer thickness in the range 5–40 nm has been developed. Evidences highlight the crucial role of the SiO2 layer in dramatically increasing photocatalytic water oxidation promoted by the nanostructure under both UV and visible illumination. An ideal thickness value of about 10 nm has been demonstrated to guarantee the plasmon‐induced resonance energy‐transfer process and to quench the Förster resonance energy‐transfer mechanism; thus, optimising the local surface plasmon resonance effect and water oxidation properties. [ABSTRACT FROM AUTHOR]

Although hollow silver nanocrystals possess unique plasmonic properties, there is a lack of robust strategies to synthesize such nanocrystals with high efficiency and controllability. To solve this problem, a new surface‐protected etching strategy to convert solid Ag nanocrystals, which are widely available from conventional syntheses, into their hollow counterparts, producing a family of hollow Ag nanocrystals is reported. Hollow Ag nanospheres and nanotubes were prepared conveniently in this way. The key was the surface modification of Ag nanocrystals by a minor amount of Pt prior to a controllable etching process, which accounts for enhanced stability of the Ag surface and subsequent etching of Ag from the inner part of the nanocrystals while retaining the overall crystal morphology. These hollow Ag nanocrystals showed distinctive optical properties, as demonstrated by the enhanced optical transmittance of flexible electrodes fabricated with Ag nanotubes, compared to nanowires. These hollow Ag nanocrystals hold promise in different plasmonic and electronic applications. Hollow silver nanospheres and nanotubes were synthesized by surface‐protected etching of their solid counterparts and showed distinctive optical properties. [ABSTRACT FROM AUTHOR]

In this work, the surface plasmon resonance effect of metallic Ag, surface oxygen vacancies (SOVs), and Bi2MoO6 (BMO) material were rationally combined to construct new oxygen‐vacancy‐rich Ag/Bi2MoO6 (A/BMO‐SOVs) photocatalysts. Their synergistic effect on the photocatalytic degradation of phenol and 4‐nitrophenol under visible‐light irradiation (λ≥420 nm) was also investigated. TEM, EPR, and Raman spectra demonstrate the co‐existence of metallic Ag nanoparticles, surface oxygen vacancies, and Bi2MoO6 due to a controlled calcination process. The experimental results disclose that the 2 %A/BMO‐SOVs‐375 sample exhibited the highest photocatalytic activity for the degradation of both phenol and 4‐nitrophenol under visible‐light irradiation, achieving nearly 100 and 80 % removal efficiency, respectively, and demonstrated the apparent reaction rate constants (kapp) 183 and 26.5 times, respectively, higher than that of pure Bi2MoO6. The remarkable photodegradation performance of A/BMO‐SOVs for organic substances is attributed to the synergistic effect between the surface oxygen vacancies, metallic Ag nanoparticles, and Bi2MoO6, which not only improves the visible‐light response ability, but also facilitates charge separation. Thus, this work provides an effective strategy for the design and fabrication of highly efficient photocatalysts through integrating surface oxygen vacancies and the surface plasmon resonance effect of nanoparticles, which has the potential for both water treatment and air purification. Let's work together! A new oxygen‐vacancy‐rich Ag/Bi2MoO6 photocatalyst was fabricated by a reliable solvothermal process combined with an impregnation–calcination approach. The photocatalyst exhibited excellent visible‐light‐driven photocatalytic performances for both phenol and 4‐nitrophenol degradation because of a synergistic effect stemming from the integration of the individual advantages of surface oxygen vacancies (SOVs), metallic Ag nanoparticles, and Bi2MoO6 (BMO). [ABSTRACT FROM AUTHOR]

Tuning localized surface plasmon resonance (LSPR) is crucial for practical applications of two-dimensional Ag nanoplates (AgNPs) and relies on the precise control of their lateral length or/and thickness. In the present seed-mediated synthetic method, by taking advantage of underpotential deposition (UPD) of Cu on the (111) surfaces of AgNPs, a solely lateral growth of AgNPs was achieved when Cu(NO3)2 was employed, while a vertical growth of AgNPs could be attained by introducing CuCl2 into our growth solutions. The lateral length and the vertical thickness of the AgNPs could be tuned in the ranges of 115 to nearly 300 nm and 13.4 to around 200 nm, respectively. Along with control of the dimensional size of AgNPs, LSPR could also be tuned in the visible to near infrared range. Plausible growth mechanisms for the precise control of the lateral and vertical growth of AgNPs were proposed. [ABSTRACT FROM AUTHOR]

In hybrid materials containing plasmonic nanoparticles such as Au and Ag, charge-transfer processes from and to Au or Ag can affect both activities and selectivity in plasmonic catalysis. Inspired by the widespread utilization of commercial Si wafers in surface-enhanced Raman spectroscopy (SERS) studies, we investigated herein the effect of the native SiO2 layer on Si wafers over the surface plasmon resonance (SPR)-mediated activities of the Au and Ag nanoparticles (NPs). We prepared SERS-active plasmonic comprised of Au and Ag NPs deposited onto a Si wafer. Here, two kinds of Si wafers were employed: Si with a native oxide surface layer (Si/SiO2) and Si without a native oxide surface layer (Si). This led to Si/SiO2/Au, Si/SiO2/Ag, Si/Au, and Si/Ag NPs. The SPR-mediated oxidation of p-aminothiophenol (PATP) to p, p′-dimercaptoazobenzene (DMAB) was employed as a model transformation. By comparing the performances and band structures for the Si/Au and Si/Ag relative to Si/SiO2/Au and Si/SiO2/Ag NPs, it was found that the presence of a SiO2 layer was crucial to enable higher SPR-mediated PATP to DMAB conversions. The SiO2 layer acts to prevent the charge transfer of SPR-excited hot electrons from Au or Ag nanoparticles to the Si substrate. This enabled SPR-excited hot electrons to be transferred to adsorbed O2 molecules, which then participate in the selective oxidation of PATP to DMAB. In the absence of a SiO2 layer, SPR-excited hot electrons are preferentially transferred to Si instead of adsorbed O2 molecules, leading to much lower PATP oxidation. [ABSTRACT FROM AUTHOR]

Color-controlled spherical Ag nanoparticles (NPs) and nanorods, with features that originate from their particle sizes and morphologies, can be synthesized within the mesoporous structure of SBA-15 by the rapid and uniform microwave (MW)-assisted alcohol reduction method in the absence or presence of surface-modifying organic ligands. The obtained several Ag catalysts exhibit different catalytic activities in the H2 production from ammonia borane (NH3BH3, AB) under dark conditions, and higher catalytic activity is observed by smaller yellow Ag NPs in spherical form. The catalytic activities are specifically enhanced under the light irradiation for all Ag catalysts. In particular, under light irradiation, the blue Ag nanorod shows a maximum enhancement of more than twice that observed in the dark. It should be noted that the order of increasing catalytic performance is in close agreement with the order of absorption intensity owing to the Ag localized surface plasmon resonance (LSPR) at irradiation light wavelength. Upon consideration of infrared thermal effect, wavelength dependence on catalytic activity, and effect of radical scavengers, it can be concluded that the dehydrogenation of AB is promoted by change of charge density of the Ag NP surface derived from LSPR. The LSPR-enhanced catalytic activity can be further realized in the tandem reaction consisting of dehydrogenation of AB and hydrogenation of 4-nitrophenol, in which a similar tendency in the enhancement of catalytic activity is observed. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (NPs) ranging in size from 40 to 100 nm were prepared in high yield by using an improved seed-mediated method. The homogeneous Ag NPs were used as building blocks for 2D assembled Ag NP arrays by using an oil/water interface. A close-packed 2D array of Ag NPs was fabricated by using packing molecules (3-mercaptopropyltrimethoxysilane) to control the interparticle spacing. The homogeneous 2D Ag NP array exhibited a strong quadrupolar cooperative plasmon mode resonance and a dipolar red-shift relative to individual Ag NPs suspended in solution. A well-arranged 2D Ag NP array was embedded in polydimethylsiloxane film and, with biaxial stretching to control the interparticle distance, concomitant variations of the quadrupolar and dipolar couplings were observed. As the interparticle distance increased, the intensity of the quadrupolar cooperative plasmon mode resonance decreased and dipolar coupling completely disappeared. The local electric field of the 2D Ag NP array was calculated by using finite difference time domain simulation and qualitatively showed agreement with the experimental measurements. [ABSTRACT FROM AUTHOR]

Metal-support interactions (MSIs) and particle size play important roles in catalytic reactions. For the first time, silver nanoparticles supported on CeO2-SBA-15 supports are reported that possess tunable particle size and MSIs, as prepared by microwave (MW) irradiation, owing to strong charge polarization of CeO2 clusters (i.e., MW absorption). Characterizations, including TEM, X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure, were carried out to disclose the influence of CeO2 contents on the Ag particle size, MSI effect between Ag nanoparticles and CeO2-SBA-15 supports, and the strong MW absorption of CeO2 clusters that contribute to the MSIs during Ag deposition. The Ag particle sizes were controllably tuned from 1.9 to 3.9 nm by changing the loading amounts of CeO2 from 0.5 to 2.0 wt %. The Ag nanoparticle size was predominantly responsible for the high turnover frequency (TOF) of 0.41 min−1 in ammonia borane dehydrogenation, whereas both particle size and MSIs contributed to the high TOF of 555 min−1 in 4-nitrophenol reduction for Ag/0.5CeO2-SBA-15, which were twice as large as those of Ag/SBA-15 without CeO2 and Ag/CeO2-SBA-15 prepared by conventional oil-bath heating. [ABSTRACT FROM AUTHOR]

Heterogeneous Catalysis Metal – support interactions (MSIs) and particle size are important for catalytic reactions. In their Full Paper on page 15746 ff., H. Yamashita and co ‐ workers report silver nanoparticles supported on CeO2 ‐ SBA ‐ 15 with tunable particle size and MSIs, owing to the preparation by microwave irradiation, which gives a strong charge polarization of the CeO2 clusters. Silver nanoparticle size and MSIs were predominantly responsible for the high turnover frequency in ammonia borane dehydrogenation and 4 ‐ nitrophenol reduction. [ABSTRACT FROM AUTHOR]