Extending the Polyol Reduction Process into the Second Dimension: Oxide Thin Film Reduction

The formation of extended metal thin fi lms ( < 5 nm) or monolayers on oxide surfaces, for applications in (electro-)catalysis, has never been achieved due to the high interfacial energy of the metal/oxide interface that always results in a 3D growth of the deposited metal. To realize 2D growth, the outermost surface of the oxide must be reduced prior to metal deposition in the same system. Here, we demonstrate that the polyol method, typically used for metal nanoparticles synthesis, can be used for the reduction of oxide thin fi lms. The reduction of the oxide layer upon heating in ethylene glycol was electrochemically monitored in situ by measuring the open circuit potential and con fi rmed by cyclic voltammetry and near ambient pressure X-ray photoelectron spectroscopy. The reduction of oxide thin fi lms could be veri fi ed for nanoparticles of Sn, Ni and Sb-doped SnO 2 in accordance with thermodynamic calculations. This method will enable the formation of metal thin fi lms and monolayers on oxide substrates for applications in (electro-)catalysis.