Prashant V. Kamat

Bio: Prashant V. Kamat is an academic researcher from University of Notre Dame. The author has contributed to research in topics: Racism & Excited state. The author has an hindex of 140, co-authored 725 publications receiving 79259 citations. Previous affiliations of Prashant V. Kamat include Indian Institute of Technology Kanpur & Council of Scientific and Industrial Research.

Best practices for reporting on heterogeneous photocatalysis.

Abstract: H photocatalysis is of broad interest in materials chemistry and materials science, particularly with the rapid growth of research attention being directed toward energy-related applications, pollution mitigation, and other related areas of environmental impact. A literature survey reveals more than 9000 papers with the word photocatalyst or photocatalysis in the title published during the last ten years (Source: Web of Science, July 3, 2014), with the number of papers published each year increasing significantly since 2005. The materials and physical chemistry journals of the American Chemical Society receive a significant number of papers in the area of photocatalysis. As editors of Chemistry of Materials, ACS Applied Materials & Interfaces, and The Journal of Physical Chemistry Letters, we have written this Editorial to draw the attention of authors, reviewers, and readers to the importance of uniform guidelines for the analysis and characterization of new and modified heterogeneous photocatalyst materials. These best practices for photocatalysis characterization and efficiency reporting are not new to the photocatalyst community; indeed, they have been repeatedly discussed within the research community over many years. Nonetheless, we as editors continue to receive papers for consideration that report on poorly characterized photocatalysts and make exaggerated claims, such as "highly efficient," "superior efficiency," or "improved efficiency," without properly disclosing the conditions and experimental procedures used to characterize the catalyst materials and determine the photocatalytic efficiencies. As a result, the major conclusions of the papers are oftentimes not supported by the experimental results, and comparisons with prior literature near impossible, which raises suspicions that the paper may be unreliable. These papers may suffer the consequence of poor review, or worse, being declined without external review. The challenge in attempting to provide a list of requirements for publication of a new or modified photocatalyst is that the diversity of materials is high, and thus delineating a one-sizefits-all template is not realistic. We hope, however, to outline the essentials that could serve as a starting point for any paper that describes photocatalytic performance. At a minimum, the following points should be addressed by each paper that discloses the performance of new or modified photocatalyst materials: Photocatalyst Characterization. New (nano)materials should be properly and fully characterized, including X-ray diffraction analysis, electron microscopy, X-ray photoelectron spectroscopy, effective surface area determination (BET measurements), light absorption characteristics (including diffuse reflectance spectroscopy, or if soluble or in thin-film form, UV−visible spectroscopy), and other techniques that may be relevant to the material(s) in question. If recording an emission spectrum, it is important to identify the origin of emission by taking an accompanying excitation spectrum. (Caution: Organic impurities often contribute to blue emission under UV excitation.) Reporting of Photocatalytic Efficiencies. The conditions under which the efficiency of a photocatalyst is determined must be carefully and thoroughly defined including the following: Catalyst loading (or area and thickness if a film), the source and wavelength of light used for illumination (if monochromatic), or the wavelength distribution of light (if broadband), the optical irradiance at the sample (mW cm−2) or total optical power impinging on the sample if liquid (mW mL−1), and the substrate concentration. Studies should also include measurement of the apparent quantum efficiency, defined as

Photoelectrochemistry of Quantized WO3 Colloids: Electron Storage, Electrochromic, and Photoelectrochromic Effects

Abstract: Electron storage effects in quantized WO[sub 3] colloids have been investigated by spectroelectrochemical and photochemical methods. Electrons trapped within the colloidal particles exhibit blue coloration with absorption in the red-IR region. From picosecond laser flash photolysis experiments, we estimate the rate constant for electron trapping to be 10[sup 10] s[sup [minus]1]. These trapped electrons are stable in an inert atmosphere and can be utilized to reduce substrates such as thiazine and oxazine dyes which have reduction potentials less negative than the conduction band of WO[sub 3]. The rate constants for the heterogeneous electron transfer at the semiconductor/electrolyte interface are in the range (0.7-2.4) [times] 10[sup 9] M[sup [minus]1] s[sup [minus]1]. 43 refs., 10 figs., 1 tab.

Nanoparticles in advanced oxidation processes

Abstract: Photocatalysis using semiconductor nanoparticles as an advanced oxidation technique (AOT) has been a focus of research by a number of groups during the last two decades. The photocatalytic approach has been adopted successfully to develop self-cleaning glasses and air purification systems. Enhancing the photoconversion efficiency, maximizing the rate of degradation, and extending the photoresponse of the semiconductor catalyst into the visible range still pose a major challenge. Recent developments that address these issues and new approaches that expand the scope of semiconductor and metal nanoparticles in AOTs and related applications are presented in this overview.

I and i

Abstract: 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 …

Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells

Abstract: 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%.

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

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

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

Abstract: 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

Visible-Light Photocatalysis in Nitrogen-Doped Titanium Oxides

Abstract: 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.