Reagent-free photochemical silver dendrite synthesis on a gallium nitride thin film as a SERS-active substrate and catalytic cluster

Abstract

Reagent-free nanostructure synthesis provides an additional dimension for green chemistry, significantly reducing chemical contamination of the environment and indirectly reducing damage to human health. Photon-generated free reactive electrons can initialize many chemical reactions without the presence of reducing agents, giving rise to clean synthetic routes. In this study, we directly synthesized silver dendroid structures on a wide bandgap GaN epitaxial thin film, which produces vast numbers of reductive electrons under continuous UV-irradiation. Uniform spheroidal nanocubes first developed on the planar GaN surface, then grew into Ag dendrites with hyperbranches. The silver crystals are interwoven and interpenetrate to give an intriguing fern texture, which doubles in role as an optical enhancer and catalytic site for many chemical reactions. In this way, a multifunctional GaN substrate is developed using a facile, green and photochemical approach, on which catalytic reactions, and simultaneously high quality SERS measurements can be performed with considerable sensitivity. Thereby, this hybrid material is exploited to reveal detailed chemical insight into liquid/solid interfaces without additional modification, well-balancing the economic and technical needs.