Formation of Cu-Rh alloy nanoislands on TiO2 for photoreduction of carbon dioxide

Abstract

In this work, the photocatalytic activity of the Cu-Rh/TiO2 system in the ultraviolet and visible regions was studied. A rough TiO2 layer was formed on a metal grid by electrophoretic deposition. The Cu-Rh nanoalloy on the surface of the TiO2 layer was obtained by the method of sequential vacuum-thermal evaporation of components followed by heat treatment of the condensate. This approach makes it possible to form Cu-Rh nanostructures of a given composition in a wide concentration range. According to the phase equilibrium diagram of the Cu-Rh system for temperatures below 1150 °C, separation two solid solutions should be observed: rich in Cu and rich in Rh. However, a detailed study of the structure by high-resolution transmission electron microscopy analysis characterizes the obtained nanoislands as a single-phase solid solution, the lattice parameter of which changes linearly in accordance with Vegard's law.The resulting photocatalytic system, which is an array of Cu-Rh nanoislands with a ratio of 25/75, 50/50, 75/25 at% on a TiO2 layer, was used for CO2 photoreduction. It has been demonstrated that TiO2 modified with Cu-Rh nanoislands has a higher photocatalytic activity in the ultraviolet region as compared to pure TiO2. At the same time, it retains it to a much greater extent in the visible range, in contrast to pure TiO2.