Metal oxide arrays from block copolymer thin film templates

Abstract

We present a simple, though uncommonly used, method to produce versatile, well-ordered, nanoscale arrays of metal oxides such as MgO, Al2O3, TiO2, MnO2, Fe2O3, Co3O4, NiO, CuO, ZnO, ZrO2, RuO2, SnO2, or Ce2O3 by decoupling metal oxide precursor incorporation from block copolymer (BCP) template formation. In this work, neat BCP thin films were cast and annealed, using standard techniques, to generate templates. The templates were immersed in a precursor solution and formed metal-polymer complexes in one polymer domain. Finally, the organics were removed in an oxidative environment to leave the templated metal oxides. As a concrete example of the method's applicability, we show that the templating method produced ordered TiO2 arrays that exhibited a 13% increase in photocatalytic activity over TiO2 produced by EISA. Furthermore, the addition of gold nanoparticles further improved photocatalytic activity by 43% on our templated TiO2, whereas gold nanoparticles on EISA TiO2 exhibited no improvement. The simplicity and modularity of the templating method makes it amenable to additional applications in catalysis, optics, and sensors.