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    The effect of the central metal atom on the structural phase transition of indium doped metal phthalocyanine
    (2013-08-30)
    Rojanasuwan, Sunit
    ;
    Prajuabwan, Pakorn
    ;
    Chanhom, Annop
    ;
    Jaruvanawat, Anuchit
    ;
    Rangkasikorn, Adirek
    We investigate the effect of central metal atom on the phthalocyanine(Pc) molecular crystals as intercalated with indium. As dopant, indium has physical interaction with some atom in the ring of Pc molecule and there is charge transfer between indium atom and Pc ring atom. Since In-doped Pc is a hole doping which increase positive charge carriers and the HOMO of ZnPc, CuPc, NiPc and MgPc are localized on the phthalocyanine ring, then, the central metal atom e.g. Zn, Cu, Ni and Mg are not directly involved with the charge transfer between indium dopant and their Pc molecule. The structural phase transition from α phase to β phase of ZnPc upon doping with indium is another evidence for the existing of charge transfer between dopant atom and matrix Pc molecule. A comparative experiment of optical absorption spectrum of each metal Pc reveals that the central metal atom will affect the forming of crystal structure whether will be α phase or β phase as intercalated with indium. © (2013) Trans Tech Publications, Switzerland.
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    Photocatalysis of heat treated sodium- and hydrogen-titanate nanoribbons for water splitting, H2/O2 generation and oxalic acid oxidation
    (2013-04-09)
    Kiatkittipong, Kunlanan
    ;
    Iwase, Akihide
    ;
    Scott, Jason
    ;
    Amal, Rose
    The photocatalytic activity of sodium titanate (Na<inf>1.48</inf>H<inf>0.52</inf>Ti<inf>3</inf>O<inf>7</inf>), sodium hexatitanate (Na<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf>), and hydrogen titanate (H<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf>) nanoribbons and anatase TiO<inf>2</inf> nanorods were compared for water splitting, oxalic acid photodegradation and H<inf>2</inf> and O<inf>2</inf> generation using sacrificial agents. The intrinsic properties of the materials were found to affect their performance depending on the particular reaction system. The Na<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf> nanoribbons, in the presence of RuO<inf>2</inf> co-catalyst, outperformed the anatase nanorods, for the water splitting reaction, generating over 10 times more H<inf>2</inf>/O<inf>2</inf>. This was thought to derive from their tunnel-like structure which provided better electron/hole separation when compared with TiO<inf>2</inf>. However, the efficient holes and electrons scavenging in the presence of sacrificial agents, methanol or AgNO<inf>3</inf>, to generate H<inf>2</inf> or O<inf>2</inf>, respectively, overwhelmed the tunnel-like structure effect. In this case photoactivity was governed by the crystal structure, with observed decreasing activity in the order TiO<inf>2</inf>>Na<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf>>H<inf>2</inf>Ti<inf>3</inf>O<inf>7</inf>~Na<inf>1.48</inf>H<inf>0.52</inf>Ti<inf>3</inf>O<inf>7</inf>, and by the band gap of the semiconductor which determined its capacity to absorb photons in producing electron/hole pairs. © 2013 Elsevier Ltd.