Black Gold: Plasmonic Colloidosomes with Broadband Absorption Self-Assembled from Monodispersed Gold Nanospheres by Using a Reverse Emulsion System

A facile approach for the fabrication of novel black plasmonic colloidosomes assembled from Au nanospheres is developed by an emulsion‐templating strategy. This self‐assembly process is based on a new reverse water‐in‐1‐butanol emulsion system, in which the water emulsion droplets can dissolve into 1‐butanol (oil) phase at an appropriate rate. These Au colloidosomes possess hexagonal close‐packed multilayer shells and show a low reflectivity and intense broadband absorption owing to the strong interparticle plasmonic coupling, which is further investigated by a finite‐difference time‐domain method. This method is universal and is suitable for self‐assembly of different noble‐metal nanoparticles into different colloidosomes. These colloidosomes have important applications in photothermal therapy, biosensors, and drug delivery. Black colloidosomes: 3D hollow plasmonic colloidosomes (see picture) composed of hexagonal close‐packed gold nanospheres were self‐assembled by a new reverse water‐in‐1‐butanol emulsion system. These gold colloidosomes display a strong plasmonic coupling effect with broadband light absorption, show black color intrinsically, and are therefore denoted as black gold.