Rhodium Oxide Nanorod Motors Powered by Light across the Full Visible Spectrum

Abstract

We report nanorod motors made of gold (Au) and rhodium oxide (Rh2O3) that move in UV and visible light (purple, blue, green, or red). These nanorods are synthesized in large quantities (109/batch) by template-assisted electrodeposition, followed by annealing, and are uniformly distributed and resist strong acids or bases. Rh2O3 forms a heterojunction with Au so that a Rh2O3–Au nanorod moves toward Au under visible light via self-electrophoresis. Its speed increases with light intensities and fuel [e.g., hydrogen peroxide (H2O2)] concentrations, reaching 28.5 μm/s in 10% H2O2 under 365 nm light of 320 mW/cm2. These nanorod motors also form dynamic and reversible clusters under light.