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

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.