Photocatalytic Growth of Hierarchical Au Needle Clusters on Highly Active TiO2 Thin Film

Abstract Hierarchical gold (Au) structures with sharp edges garner a strong interest for nanoelectronics, nanoenergy harvesting devices, and nano‐biomedical applications due the exceptional strong electric field (hot spot) enhancement at their tips. Herein, a facile method to synthesize hierarchical Au needle clusters (HAuNCs) on highly active titanium oxide (TiO 2 ) thin film is reported. Different from surfactant‐directed photochemical‐assisted synthesis methods, a photocatalytic deposition approach is demonstrated, which allows positioning and patterning of HAuNCs on TiO 2 target without using any surfactant or stabilizer. This green synthesis approach enables to control the size and the geometry of deposited HAuNCs by simply altering the photocatalytic activity of TiO 2 target, UV light intensity, and irradiation time.