Synthesis and Characterization of Rutile TiO2Nanopowders Doped with Iron Ions

Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipitation method. Obtained materials were characterized by structural (XRD), morphological (TEM and SEM), optical (UV/vis reflection and photoluminescence, and Raman), and analytical techniques (XPS and ICP-OES). XRD analysis revealed rutile crystalline phase for doped and undoped titanium dioxide obtained in the same manner. Diameter of the particles was 5–7 nm. The presence of iron ions was confirmed by XPS and ICP-OES. Doping process moved absorption threshold of TiO2into visible spectrum range. Photocatalytic activity was also checked. Doped nanopowders showed normal and up-converted photoluminescence

Electrochemical generation of ferrate in acidic media at boron-doped diamond electrodes

An extremely strong oxidant, ferrate (Fe(VI) or FeO42-), has been produced electrochemically in an acidic aqueous medium for the first time.open1137sciescopu

Electrochemical behavior of cobalt oxide films deposited at conductive diamond electrodes

The oxidation of Co(II) at a boron-doped diamond (BDD) electrode was investigated by use of anodic voltammetry. The results shows that this reaction takes place by a mechanism similar to that of cobalt metal oxidation in alkaline media. The voltammetric curves evidence a strong enhancement of the oxygen evolution current in the presence of Co(II). This behavior is consistent with cobalt oxide formation at the diamond electrode surface. Based upon these results, a simple, straightforward method for the production of high activity films on BDD electrode surfaces is demonstrated. The study of the electrochemical behavior in 1 M NaOH shows that the electrodes thus obtained exhibit promising, stable electrocatalytic performance for oxygen evolution, comparing well with those of thermally deposited cobalt electrodes. The use of BDD as a substrate for the electrocatalytic layers allows the deposition of isolated particles or discontinuous films, thus maximizing the utilization of the catalyst by avoiding the need for thick films. (C) 2003 The Electrochemical Society.open115255sciescopu

Photochemistry and photocatalysis

Photocatalysis is an important branch of catalysis and much more than that. To understand the potential applications and the working mechanisms of photocatalysis, it is necessary to know some important concepts of photochemistry, the branch of science that deals with the interaction of light and matter: (1) light excitation with a photon of suitable energy promotes a molecule or a semiconductor from the ground state to an electronically excited state that exhibits its own chemical and physical properties; (2) the most relevant consequence from the viewpoint of photocatalysis is that the excited state is both a better oxidant and a better reductant than the ground state; (3) some molecules or semiconductors can serve as photosensitizers, i.e., they can absorb light and then make available the excited state energy to promote reactions of non-absorbing species. Photosensitization and photocatalysis play an important role in nature and technology and they may take place in homogeneous or heterogeneous phase. Such processes can use sunlight (1) to convert solar energy into chemical or electrical energy, (2) to perform organic synthesis that cannot be achieved by thermal activation, and (3) to remedy pollution. Water splitting using sunlight and suitable photosensitizers and catalysts (artificial photosynthesis) is perhaps one of the most thoroughly investigated chemical processes. Breakthrough in this area can contribute to solve the energy and climate crisis, but substantial technological development is still needed