Electrical conduction in discontinuous metal films: A discussion

A concept designed to overcome the problems encountered when using photodissociation for the generation of hydrogen is discussed. The problems limiting the efficiency of photodissociation of water are the separation of the photolysis products and the high energy photons necessary for the reaction. It is shown that the dissociation energy of a large number of molecules is catalytically reduced when these molecules are in intimate contact with the surface of certain metals. It is proposed to develop a surface which will take advantage of this catalytic shift in dissociation energies to reduce the photon energy required to produce hydrogen. This same catalytic surface can be used to separate the reaction products if it is made so that one of the dissociations products is soluble in the metal and others are not. This condition is met by many metal systems such as platinum group metals which have been used commercially to separate hydrogen from other gases and liquids.

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Photocatalytic generation of hydrogen from water

The transition metal catalysts have much concerned over the last two to three decades due to their different properties from their bulk-counterparts, which cover the way for their application in various fields. It has shown superior efficiency in selectivity, performances, and stability to the heterogeneous catalysis. Carbon monoxide (CO) is a very harmful gas that exists in the atmosphere and ambient-temperature complete oxidation of it is an important process for human health protection. The performances of transition metal catalysts are highly dependent on the crystallite size, surface area, and pore volume of the catalysts. The chemisorptions of CO over transitional metal and supported catalysts were studied in this review. The transition metal catalysts have been represented an excellent catalyst from lower cost, thermally, activity, and selectivity point of view. This investigation will show scientific basis for potential design of transition metal oxide catalysts for CO oxidation.

Advances in transition metal oxide catalysts for carbon monoxide oxidation: a review

The performance of electrodes, prepared from amorphous CoxByHz nanoparticles without additives, in 20% KOH solution was tested by means of cyclic voltammetry and chronopotentiometry. Peaks, assigned to hydrogen adsorption and desorption, are observed in the cyclic voltammograms. After charging, hydrogen atoms occupy different types of sites in the substrate, from which electrochemical desorption occurs. An increase in hydrogen content as a result of repeated cycling was established. Discharge capacity of the electrodes, estimated from the chronopotentiometric discharge curves obtained, is about 250mAhg−1. The observed changes in hydrogen and boron content, due to electrochemical treatment, indicate that the electrode material is an active participant in the whole electrochemical process. Hypotheses for the reaction mechanism are proposed.

Nanoparticles produced by borohydride reduction as precursors for metal hydride electrodes

Controlling carbon monoxide emissions from automobile vehicle exhaust using copper oxide catalysts in a catalytic converter

Catalytic oxidation of hydrogen and carbon monoxide was carried out by using catalysts, obtained from Ni75B25 and Ni73Cu5P22 amorphous alloys. The alloys were treated with HNO 3 acid and oxidized at 730 K in air. The catalytic activity was measured in the temperature interval 430–600 K. The rate constants and the activation energies of the processes were determined. The untreated alloys showed a catalytic activity, that increased after various treatments. The results obtained pointed to a higher catalytic activity for hydrogen oxidation as compared to that of carbon monoxide.

D. Lazarov

Papers

Catalytic activity of nickel based amorphous alloys for oxidation of hydrogen and carbon monoxide

The structure of metal films and the changes in their conductivity during adsorption: I. Adsorption of water vapor on copper

The structure of gallium films and the changes in their conductivity during adsorption of oxygen, mercury and water vapours