There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Two organolead halide perovskite nanocrystals, CH3NH3PbBr3 and CH3NH3PbI3, were found to efficiently sensitize TiO2 for visible-light conversion in photoelectrochemical cells. When self-assembled on mesoporous TiO2 films, the nanocrystalline perovskites exhibit strong band-gap absorptions as semiconductors. The CH3NH3PbI3-based photocell with spectral sensitivity of up to 800 nm yielded a solar energy conversion efficiency of 3.8%. The CH3NH3PbBr3-based cell showed a high photovoltage of 0.96 V with an external quantum conversion efficiency of 65%.

Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells

Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

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Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.

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Visible-Light Photocatalysis in Nitrogen-Doped Titanium Oxides

Mastering the Art of Scientific Publication

Light Induced Processes in CsPbBr3–Au Hybrid Nanocrystals: Electron Transfer and Expulsion of Au

The performance of photoelectrochemical cells made of an n‐type TiO2 photoanode and the O2/OH− redox electrolyte system have been studied at different temperatures. It has been found that when only the photoanode compartment is heated, the open‐circuit voltage decreases (∼2.0 mV K−1) and the short‐circuit current increases (∼0.8 mA m−2 K−1); however, the power output shows a small increase and a fall thereafter. The behavior is similar to that of Schottky‐barrier solar cells. When both of the electrode compartments are heated, the power output increases with increasing temperature (∼0.4 mW m−2 K−1) and this can be attributed to the enhancement of the rate of the electrochemical reaction at the counterelectrode.

Temperature effects in photoelectrochemical cells

An electroanalytical method has been developed to investigate the uptake of redox-active species by the humic acid substances. The Suwannee River humic acid (SHA) films were first cast on a glassy carbon electrode using an electrophoretic approach. The binding of a series of redox-active species to these SHA films was then probed using cyclic voltammetry at a rotating disk electrode. Neutral molecules such as hydroquinone and cationic species such as methyl viologen are able to bind with the humic membrane and exhibit high redox activity within the film. On the other hand, anionic species such as ferrocyanide are unable to attach themselves to the SHA films and thus exhibit negligible electrochemical activity. Cyclic voltammetric study of SHA films has also facilitated the determination of the partitioning constants and identification of the effect of coadsorbed ions (Ca2+) on the binding of redox species. The electroanalytical method described in this study opens up new avenues to examine the interaction...

Selective electrochemical detection of ionic and neutral species using films of Suwannee River humic acid

The oxidation of dimethyl methylphosphonate (DMMP) was examined under ultrasonic conditions (640 kHz) in oxygen saturated aqueous solutions. Acetic acid, formic acid, methylphosphonic acid, phosphate, and oxalic acid have been identified as the major products produced during the sonolytic irradiation of DMMP. The initial rates of oxidation were determined as a function of initial DMMP concentration. The kinetic behavior of the system is consistent with the Langmuir-Hinshelwood model implying oxidative processes occur at or near the gas-liquid interface during cavitation. Mechanistic implications and conclusions are discussed based on the product distributions and kinetic parameters.

Prashant V. Kamat

Papers

Mastering the Art of Scientific Publication

Light Induced Processes in CsPbBr3–Au Hybrid Nanocrystals: Electron Transfer and Expulsion of Au

Temperature effects in photoelectrochemical cells

Selective electrochemical detection of ionic and neutral species using films of Suwannee River humic acid

Reaction Pathways and Kinetic Parameters of Sonolytically Induced Oxidation of Dimethyl Methylphosphonate in Air Saturated Aqueous Solutions