Polyurethane sponge facilitating highly dispersed TiO₂ nanoparticles on reduced graphene oxide sheets for enhanced photoelectro-oxidation of ethanol

Three-dimensional (3D) porous polyurethane sponge serves as the sacrificial scaffold for the hydrothermally-synthesized anatase TiO₂-reduced graphene oxide (RGO) composites. The internal channel of the 3D polyurethane structure provides larger exposed TiO₂ seeding and crystal growth area on the pre-adsorbed graphene oxide during the synthesis. The uniform pore size within the polyurethane also prevents severe aggregation of TiO₂ nanoparticles. As a result, TiO₂ nanoparticles are finely dispersed on the RGO sheets. In addition to the general advantages of introducing graphitic carbon to TiO₂ (i.e. hydrophobic carbon for preferential organic adsorption and excellent electron transport of RGO), the presence of polyurethane sponge during the synthesis offers larger contact area between TiO₂ and RGO which is facilitated by the excellent dispersion of TiO₂. Besides, formation of Ti-O-C species is found at the interface and it extends the light absorption of the composite into visible light region. Combining the localized organic adsorption adjacent to TiO₂, efficient charge transfer from large contact area of TiO₂-RGO and the extended light response of the composite, this material demonstrates enhanced photoelectrochemical oxidation of ethanol.