Sang-Chul Moon

Photocatalytic production of hydrogen from water using TiO2 and B/TiO2

Abstract Photocatalytic decomposition of water has been studied by using TiO2 (P25) and B/TiO2 photocatalysts. Yield of the photocatalytic decomposition of water by TiO2 (P25) depended on direction of light irradiation. The photocatalytic activity was about 103 times as high when the reaction cell was irradiated from the top as from the bottom. Modification of TiO2 with boron oxides was found to be very effective for photocatalytic decomposition of water. TiO2 modified with boron oxides exhibited high reactivity for the decomposition of water indifferently to the direction of light irradiation.

Characterization of titanium-boron binary oxides and their photocatalytic activity for stoichiometric decomposition of water

Abstract A titanium-boron binary oxide has been prepared by sol–gel method and used as a photocatalyst for the decomposition of water. The structure of titanium oxide species in the Ti/B binary oxide was amorphous before and crystal after calcination in O2, while the boron oxide species maintained its amorphous state. With increasing calcination temperature, the crystalline structure of titanium oxides changed from an anatase phase to a rutile phase. Pt-loaded Ti/B photocatalysts decomposed water stoichiometrically in aqueous suspension system. Their photocatalytic activity decreased markedly with increase in the calcination temperature, indicating that the photocatalytic activity of the Ti/B binary oxide was strongly dependent on the crystal phase of the titanium oxide in the Ti/B binary oxide. A remarkable yield in the reaction of water decomposition was obtained when Na2CO3 was added in the Pt-loaded Ti/B binary oxide suspension.

Photocatalytic decomposition of liquid-water on the Pt-loaded TiO2 catalysts: Effects of the oxidation states of Pt species on the photocatalytic reactivity and the rate of the back reaction

The photocatalytic decomposition of liquid water on Pt-loaded TiO2 (Pt/TiO2) catalysts was investigated. The results obtained by XPS and XRD measurements of the catalysts as a function of the calcination temperature as well as the photocatalytic decomposition reactions of H2O clearly indicate that controlling the oxidation state of Pt as well as the amount of loaded Pt species are both important factors in the design of water-splitting photocatalysts having high efficiency and stoichiometry.

The adsorption and activation of CO molecules on ZrO2 catalysts having low-coordinated surface sites

The adsorption and activation of CO molecules on microcrystalline ZrO2 were investigated by photoluminescence (PL), UV, FT-IR, and ESR measurements. The ZrO2 catalysts degassed at high temperatures exhibited abnormal absorption and photoluminescence associated with the presence of low-coordinated surface sites. The addition of CO molecules onto the pretreated ZrO2 catalysts led to the formation of various CO adsorption species. Moreover, increasing the contact time gave rise to polymeric radical anion species of CO showing that UV-irradiation of the ZrO2 catalysts in the presence of CO promoted the formation of these radical anion species of CO.

Photoluminescence properties of La2O3 methane coupling catalysts

La2O3 catalysts prepared at 923 K (La2O3-LT) and 1073 K (La2O3-HT) exhibit different photoluminescence properties due to notably different concentrations of ions in position of low coordination at the surface or coordinatively unsaturated surface sites (cus). The catalyst which exhibits the higher yields of photoluminescence due to the higher concentration of cus corresponds to the one which gives the higher C2+ selectivity in the oxidative methane coupling reaction.

4.17 Dynamics of the Adsorption and Hydrogenation of CO on Active ZrO2 Catalyst: –In Situ Photoluminescence, FT-IR, and ESR Investigations–

Abstract The role of coordinatively unsaturated surface sites (CUS) onto the activation of CO adsorbed on the ZrO 2 catalyst was studied, the results indicating that the various types of adsorbed CO species involving polymeric radical anion species of CO were formed on the CUS of the ZrO 2 catalyst. It was also found that these CO adsorption species easily react with hydrogen to form CH 4 and CH 3 OH, showing the different reactivity with the kinds of CO adsorption species.