Tunable growth of silver nanobelts on monolithic activated carbon with size-dependent plasmonic response.

Silver is one of the most important materials in plasmonics. Tuning the size of various silver nanostructures has been actively pursued in the last decade. However, silver nanobelt, a typical one-dimensional silver nanostructure, has not been systematically studied as to tuning its size for controllable plasmonic response. Here we show that silver nanobelts, with mean width ranging from 45 to 105 nm and thickness at ca. 13 nm, can grow abundantly on monolithic activated carbon (MAC) through a galvanic-cell reaction mechanism. The widths of silver nanobelts are positively correlated to the growth temperatures. The width/thickness ratio of the silver nanobelts can be adjusted so that their transversal plasmonic absorption peaks can nearly span the whole visible light band, which endows them with different colours. This work demonstrates the great versatility of a simple, green and conceptually novel approach in controlled synthesis of noble metal nanostructures.

Morphosynthesis of cubic silver cages on monolithic activated carbon.

Cubic silver cages were prepared on monolithic activated carbon (MAC) pre-absorbed with Cl(-), SO4(2-), or PO4(3-) anions. Silver insoluble salts served as templates for the morphosynthesis of silver cages. The silver ions were reduced by reductive functional groups on MAC micropores through a galvanic cell reaction mechanism.

Full-color CO2 gas sensing by an inverse opal photonic hydrogel.

CO2 gas sensing is of great importance because of the impact of CO2 on global climate change. Here, utilizing an inverse opal hydrogel, we describe a CO2 gas sensing method that allows highly sensitive and selective detection over a wide concentration range. The CO2 sensor is specific, quantitative, interference tolerant and without the need for special instruments.

Green "planting" nanostructured single crystal silver.

Design and fabrication of noble metal nanocrystals have attracted much attention due to their wide applications in catalysis, optical detection and biomedicine. However, it still remains a challenge to scale-up the production in a high-quality, low-cost and eco-friendly way. Here we show that single crystalline silver nanobelts grow abundantly on the surface of biomass-derived monolithic activated carbon (MAC), using [Ag(NH3)2]NO3 aqueous solution only. By varying the [Ag(NH3)2]NO3 concentration, silver nanoplates or nanoflowers can also be selectively obtained. The silver growth was illustrated using a galvanic-cell mechanism. The lowering of cell potential via using [Ag(NH3)2]⁺ precursor, together with the AgCl crystalline seed initiation, and the releasing of OH⁻ in the reaction process, create a stable environment for the self-compensatory growth of silver nanocrystals. Our work revealed the great versatility of a new type of template-directed galvanic-cell reaction for the controlled growth of noble metal nanocrystals.

Bioinspired synthesis of calcium carbonate hollow spheres with a nacre-type laminated microstructure.

In this Article, we combine the characters of hyperbranched polymers and the concept of double-hydrophilic block copolymer (DHBC) to design a 3D crystal growth modifier, HPG-COOH. The novel modifier can efficiently control the crystallization of CaCO(3) from amorphous nanoparticles to vaterite hollow spheres by a nonclassical crystallization process. The obtained vaterite hollow spheres have a special puffy dandelion-like appearance; that is, the shell of the hollow spheres is constructed by platelet-like vaterite mesocrystals, perpendicular to the globe surface. The cross-section of the wall of a vaterite hollow sphere is similar to that of nacres in microstructure, in which platelet-like calcium carbonate mesocrystals pile up with one another. These results reveal the topology effect of the crystal growth modifier on biomineralization and the essential role of the nonclassical crystallization for constructing hierarchical microstructures.

Tunable growth of nanodendritic silver by galvanic-cell mechanism on formed activated carbon.

Well-defined silver dendritic nanostructures have been prepared in large quantities in an ambient environment using formed activated carbon (FAC) only. A reasonable mechanism (step 1: reduction by surface reductive groups; step 2: growing in the form of a galvanic cell) is suggested.

From crabshell to chitosan-hydroxyapatite composite material via a biomorphic mineralization synthesis method.

Hydroxyapatite-polymer composite materials, as biological bone tissue materials, have become an important research direction. In this paper, the calcium carbonate from the crabshells was transformed into hydroxyapatite by a hydrothermal process. According to the method that we called Biomorphic Mineralization synthesis, we obtained a novel kind of hydroxyapatite-chitosan composite materials which reserved the natural perfect structure of the original crabshells. Benefited from its fine micro-structure as the crabshells, this kind of materials held a high value of tensile modulus, which is expected to be promising bone tissue engineering applications.