TiO2 photocatalysis and related surface phenomena

As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO2) semiconductor materials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applications. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 structure, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed. Emphasis is given to the origin of visible light absorption and the reactive oxygen species generated, deduced by physicochemical and photoelectrochemical methods. Various applications of VLA TiO2, in terms of environmental remediation and in particular water treatment, disinfection and air purification, are illustrated. Comprehensive studies on the photocatalytic degradation of contaminants of emerging concern, including endocrine disrupting compounds, pharmaceuticals, pesticides, cyanotoxins and volatile organic compounds, with VLA TiO2 are discussed and compared to conventional UV-activated TiO2 nanomaterials. Recent advances in bacterial disinfection using VLA TiO2 are also reviewed. Issues concerning test protocols for real visible light activity and photocatalytic efficiencies with different light sources have been highlighted.

/pdf/a-review-on-the-visible-light-active-titanium-dioxide-2qg81s4yao.pdf

A review on the visible light active titanium dioxide photocatalysts for environmental applications

5.1. Nanoalloys of Group 11 (Cu, Ag, Au) 865 5.1.1. Cu−Ag 866 5.1.2. Cu−Au 867 5.1.3. Ag−Au 870 5.1.4. Cu−Ag−Au 872 5.2. Nanoalloys of Group 10 (Ni, Pd, Pt) 872 5.2.1. Ni−Pd 872 * To whom correspondence should be addressed. Phone: +39010 3536214. Fax:+39010 311066. E-mail: ferrando@fisica.unige.it. † Universita di Genova. ‡ Argonne National Laboratory. § University of Birmingham. | As of October 1, 2007, Chemical Sciences and Engineering Division. Volume 108, Number 3

Nanoalloys: From Theory to Applications of Alloy Clusters and Nanoparticles

Metal species with different size (single atoms, nanoclusters, and nanoparticles) show different catalytic behavior for various heterogeneous catalytic reactions. It has been shown in the literature that many factors including the particle size, shape, chemical composition, metal–support interaction, and metal–reactant/solvent interaction can have significant influences on the catalytic properties of metal catalysts. The recent developments of well-controlled synthesis methodologies and advanced characterization tools allow one to correlate the relationships at the molecular level. In this Review, the electronic and geometric structures of single atoms, nanoclusters, and nanoparticles will be discussed. Furthermore, we will summarize the catalytic applications of single atoms, nanoclusters, and nanoparticles for different types of reactions, including CO oxidation, selective oxidation, selective hydrogenation, organic reactions, electrocatalytic, and photocatalytic reactions. We will compare the results o...

Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles.

The use of efficiency observables to measure activity is of critical importance in order to progress in the quantitative assessment of the functional properties of photo-catalysts in energy and environmental related applications. In this quest, the analysis of the experimental/computational procedures to obtain efficiency observables and the associated unsolved problems are reviewed. Particularly, the contribution analyzes the current efforts to fully interpret the effect(s) of the light-matter interaction as well as the dimensionality of the observable.

Interpreting quantum efficiency for energy and environmental applications of photo-catalytic materials

Combining Infrared Spectroscopy with X‐ray Techniques for Interrogating Heterogeneous Catalysts

Heterogeneous photocatalysts are rarely employed in industry for the synthesis of commodity chemicals due to efficiency problems Now, a photochromic Bi2WO6–x/amorphous-BiOCl composite is reported, which features a remarkable activity for the photocatalytic oxidation of toluene into benzaldehyde and benzoic acid

Chromism and catalysis shake hands

Introduction the World of Oxide Nanomaterials

The phase behavior of a 1%Pd-0.5%Cu bimetallic catalyst during reduction has been followed by X-ray absorption near-edge structure (XANES). The analysis of the XANES spectra by Factor Analysis was used to determine that after calcination the active components are hosted in three different phases: a Cu-Pd mixed oxide, PdO and Cu 0+ ions exchanged into L-zeolite positions. At the Pd K-edge, an intermediate compound is detected in the reduction process. The reduction of the catalyst yields only one phase, a substitutionally disordered Pd 50 Cu 50 alloy.

/pdf/phase-behavior-of-a-pd-cu-bimetallic-catalyst-during-1x99q4kxx2.pdf

Marcos Fernández-García

Papers

Interpreting quantum efficiency for energy and environmental applications of photo-catalytic materials

Combining Infrared Spectroscopy with X‐ray Techniques for Interrogating Heterogeneous Catalysts

Chromism and catalysis shake hands

Introduction the World of Oxide Nanomaterials

Phase Behavior of a Pd-Cu Bimetallic Catalyst During Temperature-Programmed Reduction