Ahiud Morag

Transparent, conductive, and SERS-active Au nanofiber films assembled on an amphiphilic peptide template

The use of biological materials as templates for functional molecular assemblies is an active research field at the interface between chemistry, biology, and materials science. We demonstrate the formation of gold nanofiber films on β-sheet peptide domains assembled at the air/water interface. The gold deposition scheme employed a recently discovered chemical process involving spontaneous crystallization and reduction of water-soluble Au(SCN)4(1-) upon anchoring to surface-displayed amine moieties. Here we show that an interlinked network of crystalline Au nanofibers is readily formed upon incubation of the Au(iii) thiocyanate complex with the peptide monolayers. Intriguingly, the resultant films were optically transparent, enabled electrical conductivity, and displayed pronounced surface enhanced Raman spectroscopy (SERS) activity, making the approach a promising avenue for construction of nano-structured films exhibiting practical applications.

Porous graphene oxide chemi-capacitor vapor sensor array

A new type of cross-selective gas sensor has been developed, based on a vapor-induced capacitance modulation of chemically-functionalized porous graphene oxide (pGO). The dielectric pGO matrix was assembled in situ upon an electrode surface via a combined room-temperature annealing/freeze-drying process. Extraordinary vapor sensing properties are demonstrated, specifically extremely high sensitivity, wide dynamic range, rapid response and recovery times, fidelity, and detection of a broad range of molecular targets. The excellent sensing capabilities correspond to the open porous framework of pGO and high surface area within the pores, as well as molecular interactions between the vapor molecules and functional units displayed on the pGO framework. Array-based identification of different vapors is demonstrated via functionalization of the pGO scaffolds with distinct chemical residues.

High surface area electrodes by template-free self-assembled hierarchical porous gold architecture.

The electrode active surface area is a crucial determinant in many electrochemical applications and devices. Porous metal substrates have been employed in electrode design, however construction of such materials generally involves multistep processes, generating in many instances electrodes exhibiting incomplete access to internal pore surfaces. Here we describe fabrication of electrodes comprising hierarchical, nano-to-microscale porous gold matrix, synthesized through spontaneous crystallization of gold thiocyanate in water. Cyclic voltammetry analysis revealed that the specific surface area of the conductive nanoporous Au microwires was very high and depended only upon the amount of gold used, not electrode areas or geometries. Application of the electrode in a pseudo-capacitor device is presented.

Catalytic Au Wool-Ball-Shaped Nanostructures

Gold nanoparticles shaped like wool balls were synthesized through the simple, spontaneous crystallization/reduction of gold thiocyanate [Au(SCN)4−] in water, without co‐addition of nucleating seeds, templating compounds, or reducing agents. The Au nanowool balls were highly uniform in size and displayed a remarkable nanoribbon surface morphology. Size and structural modulation of the particles were accomplished through the tuning of the concentration of the gold complex, as well as upon adding small quantities of organic solvents. The unique corrugated morphology and high surface area of the Au nanowool balls enabled their use as effective catalytic substrates for methanol oxidation and nitrophenol reduction.