Green synthesis of chitosan/glutamic acid/agarose/Ag nanocomposite hydrogel as a new platform for colorimetric detection of Cu ions and reduction of 4-nitrophenol.

In this study, the green synthesis of chitosan/glutamic acid/agarose/Ag (Chi/GA/Aga/Ag) nanocomposite hydrogel was obtained via in situ reduction of Ag ions during the crosslinking process of chitosan-agarose double network hydrogels. The rich hydroxyl, carboxyl and amino groups in both agarose, chitosan, and glutamic acid can effectively control the growth, dispersion and immobilization of nearly spherical Ag nanoparticles (70 nm) in the Chi/GA/Aga/Ag composite hydrogel. Glutamic acids can act as the structure-directing agents to induce the formation of chitosan/glutamic acid hydrogel.

Functionalized agarose hydrogel with in situ Ag nanoparticles as highly recyclable heterogeneous catalyst for aromatic organic pollutants.

In the present research work, a highly recyclable catalyst of Ag-based agarose (HRC-Ag/Agar) hydrogel was successfully fabricated through a simple and efficient in situ reduction method without the aid of additional surface active agent. The interaction between the rich hydroxyl functional (-OH) groups in agarose and Ag can effectively control the growth and dispersion of Ag nanoparticles (NPs) in the HRC-Ag/Agar hydrogel and keep Ag NPs free from chemical contamination, which also guarantees the reusability of HRC-Ag/Agar hydrogel as catalysts. HRC-Ag/Agar hydrogel without freeze drying and calcination was investigated for their potential applications as highly active/recyclable catalysts in reducing aromatic organic pollutants (p-nitrophenol (4-NP), methylene blue (MB) and rhodamine B (RhB)) by KBH.

Graphene Coated Dielectric Hierarchical Nanostructures for Highly Sensitive Broadband Infrared Sensing.

Broadband infrared (IR) absorption is sought after for wide range of applications. Graphene can support IR plasmonic waves tightly bound to its surface, leading to an intensified near-field. However, the excitation of graphene plasmonic waves usually relies on resonances.

Large-Area Monolayer Films of Hexagonal Close-Packed Au@Ag Nanoparticles as Substrates for SERS-Based Quantitative Determination.

In this work, quasi-spherical, small-sized, citrate-stabilized, core-shell (CS)-structured Au@Ag nanoparticles (NPs) with Ag shells of controlled thicknesses ( = 0, 1.25, 3.25, and 5.

Fe(II)-Assisted one-pot synthesis of ultra-small core-shell Au-Pt nanoparticles as superior catalysts towards the HER and ORR.

In this work, uniform ultra-small core-shell Au-Pt nanoparticles (denoted as USCS Au-Pt NPs) with Au-decorated Pt surfaces are successfully prepared by Fe(ii)-assisted one-pot co-reduction of Au(iii) ions and Pt(ii) ions in a citrate solution. The as-prepared USCS Au38.4@Au9.

Fabrication of Au aerogels with {110}-rich facets by size-dependent surface reconstruction for enzyme-free glucose detection.

In this work, a series of Au aerogels with exposed {110}-facets were successfully synthesized by Ostwald-ripening between two differently-sized gold nanoparticles (Au NPs). On the basis of the results of de-convoluting CV analysis and size variation of large Au NPs during their formation process, it is found that the size ratio (R) between two differently-sized Au NPs is crucial for the occurrence of surface reconstruction during the Ostwald-ripening process. Moreover, the R can be used to estimate the extent of surface reconstruction and the critical R for the occurrence of surface reconstruction in our case is about 5.

Size Control Synthesis of Monodisperse, Quasi-Spherical Silver Nanoparticles To Realize Surface-Enhanced Raman Scattering Uniformity and Reproducibility.

In this work, we reported the synthesis of monodisperse, quasispherical Ag nanoparticles (NPs) with sizes of 40-300 nm by using ascorbic acid reduction of a silver-ammonia complex onto preformed, 23 nm Ag-NP seeds in the aqueous solution with an optimal pH of about 9.6 at room temperature. The as-prepared Ag NPs with such a large size span (from 40 to 300 nm) and high quality by one-pot seeded growth method are reported for the first time to the best of our knowledge.

Regulating Surface Facets of Metallic Aerogel Electrocatalysts by Size-Dependent Localized Ostwald Ripening.

It is well known that the activity and stability of electrocatalysts are largely dependent on their surface facets. In this work, we have successfully regulated surface facets of three-dimensional (3D) metallic Au aerogels by salt-induced assembly of citrate-stabilized gold nanoparticles (Au NPs) of two different sizes and further size-dependent localized Ostwald ripening at controlled particle number ratios, where m and n represent the size of Au NPs. In addition, 3D Au -Pd aerogels were further synthesized on the basis of Au aerogels and also bear controlled surface facets because of the formation of ultrathin Pd layers on Au aerogels.

Simple Synthesis of Au-Pd Alloy Nanowire Networks as Macroscopic, Flexible Electrocatalysts with Excellent Performance.

The present work introduces a new way to prepare Au-Pd alloy nanowire networks (NWNs) via deposition of Pd atoms onto Au nanowires in reaction media at room temperature without the aid of additional reducing agents. Thanks to their excellent colloidal stability in water as well as in ethanol, the resulting NWNs can be utilized to produce composite thin films with Nafion (perfluorinated sulfonic acid) with dimensions above dozens of square centimeters by means of solution casting on the glass substrate. Most importantly, these films can be easily transferred onto different solid substrates by lift-off technology.

Revitalizing the Frens Method To Synthesize Uniform, Quasi-Spherical Gold Nanoparticles with Deliberately Regulated Sizes from 2 to 330 nm.

In this work, we have successfully developed a new and consistent model to describe the growth of gold nanoparticles (Au NPs) via citrate reduction of auric acid (HAuCl4) by carefully assessing the temporal evolution of the NP sizes and surface charges by means of dynamic light scattering (DLS) and zeta-potential measurements. The new model demonstrates that the nucleation and growth of the Au NPs occur exclusively in the particles of the complexes of Au(+) ions and sodium acetone dicarboxylate (SAD) derived from the citrate/HAuCl4 redox reaction, which proceeds as described by the classic LaMer model. Concomitant with the Au NP growing therein, the Au(+)/SAD complex particles undergo reversible agglomeration with the reaction time, which may result in an abnormal color change of the reaction media but have little impact on the Au NP growth.