It is now well-known that the size, shape, and composition of nanomaterials can dramatically affect their physical and chemical properties, and that technologies based on nanoscale materials have the potential to revolutionize fields ranging from catalysis to medicine. Among these materials, anisotropic particles are particularly interesting because the decreased symmetry of such particles often leads to new and unusual chemical and physical behavior. Within this class of particles, triangular Au and Ag nanoprisms stand out due to their structure- and environment-dependent optical features, their anisotropic surface energetics, and the emergence of reliable synthetic methods for producing them in bulk quantities with control over their edge lengths and thickness. This Review will describe a variety of solution-based methods for synthesizing Au and Ag triangular prismatic structures, and will address and discuss proposed mechanisms for their formation.

Colloidal Gold and Silver Triangular Nanoprisms

Visible light-driven water splitting using cheap and robust photocatalysts is one of the most exciting ways to produce clean and renewable energy for future generations. Cutting edge research within the field focuses on so-called “Z-scheme” systems, which are inspired by the photosystem II–photosystem I (PSII/PSI) coupling from natural photosynthesis. A Z-scheme system comprises two photocatalysts and generates two sets of charge carriers, splitting water into its constituent parts, hydrogen and oxygen, at separate locations. This is not only more efficient than using a single photocatalyst, but practically it could also be safer. Researchers within the field are constantly aiming to bring systems toward industrial level efficiencies by maximizing light absorption of the materials, engineering more stable redox couples, and also searching for new hydrogen and oxygen evolution cocatalysts. This review provides an in-depth survey of relevant Z-schemes from past to present, with particular focus on mechanist...

Mimicking Natural Photosynthesis: Solar to Renewable H2 Fuel Synthesis by Z-Scheme Water Splitting Systems.

Counter-electrode function in nanocrystalline photoelectrochemical cell configurations

We describe the electrogenerated chemiluminescence (ECL) processes of the Ru(bpy)32+ (bpy = 2,2‘-bipyridyl)/tripropylamine (TPrA) system at glassy carbon, platinum, and gold electrodes. The electrochemical behavior of TPrA on different electrode materials and its influence on the ECL process are demonstrated. At glassy carbon electrodes, the direct oxidation of TPrA began at ∼0.6 V vs SCE and exhibited a broad irreversible anodic peak. Two ECL waves were observed, one in the potential region more negative than 1.0 V vs SCE and one at more positive potentials. The first ECL process apparently occurs without the electrogeneration of Ru(bpy)33+, in contrast to that of the second ECL wave. At Pt and Au electrodes, however, the formation of surface oxides significantly blocked the direct oxidation of TPrA. An ECL wave below 1.0 V did not appear at Pt and was very weak at gold. The ECL peaks at potentials of 1.1−1.2 V were also much weaker than those observed at the glassy carbon electrode. These results showed...

Electrogenerated chemiluminescence. 66. The role of direct coreactant oxidation in the ruthenium tris(2,2')bipyridyl/tripropylamine system and the effect of halide ions on the emission intensity

Methods of forming nanoprisms or nanorods from gold seed particles by adding controlled amounts of iodide ion to the growth solution are disclosed.

Halide ion control of seed mediated growth of anisotropic gold nanoparticles

The oxidative chemisorption and cathodic stripping reductive desorption of iodine have been compared at smooth polycrystalline and well-defined Au(111) single-crystal electrodes. Experimental measurements were based upon cyclic voltammetry, thin-layer coulometry, X-ray photoelectron spectroscopy, Auger electron spectroscopy, and low-energy electron diffraction. The results indicate that iodide is oxidatively adsorbed as zerovalent atomic iodine at potentials between −0.4 V and +0.4 V (Ag/AgCl reference); at lower potentials, surface iodine is reductively desorbed as aqueous iodide, while at considerably more positive potentials, it is oxidized to aqueous iodate

Anodic underpotential deposition and cathodic stripping of iodine at polycrystalline and single-crystal gold: studies by LEED, AES, XPS, and electrochemistry

Spectroscopic and electrochemical studies of iodine coordinated to noble-metal electrode surfaces

Substrate-mediated adsorbate-adsorbate interactions: effect of submonolayer coverage and coadsorbed iodine on the reversible redox of 2,5-dihydroxythiophenol chemisorbed at gold and platinum

The chemisorption at monolayer coverages of various organic molecules from aqueous solutions onto smooth polycrystalline electrodes and the resistance of the resulting monolayers towards electrochemical oxidation have been studied. This survey represents the preliminary stage in a series of investigations aimed at better understanding, at the atomic level, of metal passivation by monolayer organic films. The electrodes studied (Rh, Pd, Ir, Pt, and Au) are those whose anodic dissolution is preceded by surface-oxide formation. For these metals, corrosion resistance can be associated with the retardation of the surface oxidation; hence, the extent of surface-oxide retardation is one measure of the passivation characteristics of an organic monolayer. Thirty-eight organic compounds containing at least one surface-active functional group were investigated: alkenes, alkynes, aromatics, heterocyclic aromatics, alcohols, phenols, sulfides, amines, amides, nitriles, CO, aldehydes, carboxylates, esters, and...

Susan L. Michelhaugh

Papers

Anodic underpotential deposition and cathodic stripping of iodine at polycrystalline and single-crystal gold: studies by LEED, AES, XPS, and electrochemistry

Spectroscopic and electrochemical studies of iodine coordinated to noble-metal electrode surfaces

Substrate-mediated adsorbate-adsorbate interactions: effect of submonolayer coverage and coadsorbed iodine on the reversible redox of 2,5-dihydroxythiophenol chemisorbed at gold and platinum

The Influence of Chemisorbed Organic Monolayers on Electrode Surface Oxidation

Reversible redox, hydrodesulfurization and anodic oxidation of chemisorbed thiophenols: A comparison at platinum and gold electrodes