This presentation will report on the sensor applicability of self-organized nanoporous anodic gallium oxide.  In our previous study (B. Pandey, P. S. Thapa, D. A. Higgins, T. Ito,Langmuir 2012 , 28, 13705.), we have found that nanoporous gallium oxide monoliths with a narrow diameter distribution (relative standard deviation ca. 10-20%) can be fabricated by anodizing solid metallic gallium in ice-cooled 4 and 6 M aqueous H2SO4 at 10 V and 15 V.  As with nanoporous anodic alumina, the diameter of anodic gallium oxide nanopores can be controlled in the range of 18-40 nm by varying the H2SO4 concentration and anodization voltage.  Nanoporous anodic gallium oxide can be formed from solid metallic gallium that is introduced at the end of a glass capillary as its liquid form and then frozen.  Importantly, the resulting anodic gallium oxide contains sulfate ions that are doped during anodization.  This finding leads to a hypothesis that the physicochemical properties of the anodic gallium oxide is different from that of common gallium oxide that are known as a wide bandgap semiconductor.  Here, potentiometric responses to inorganic cations and anions are investigated for nanoporous anodic gallium oxide formed at the end of a capillary.  The potentiometric responses are compared to those of capillary-incorporated metallic gallium monoliths with and without nonporous barrier oxide layer formed by anodization at neutral pH.  We have found that nanoporous anodic gallium oxide monoliths exhibit pH-dependent potentiometric responses with slope closer to the theoretical slope (ca. 54 mV/decade at 0 �C) at the pH range of 4-8.  Interferences from other ions examined are relatively minor.  The observation of the better response may attribute to the relatively large thickness of the anodic gallium oxide layer with a higher electrical conductivity due to the doping.

Self-organized nanoporous anodic gallium oxide as a sensor material

246th National Meeting (2013)

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