Black Gold for Broadband Solar Harvesting

Plasmonic coupling between metallic nanoparticles enables broadband light absorption beyond the narrow resonances of conventional systems, intensifying the light-matter interactions for solar energy harvesting and photocatalysis. Black gold, gold nanoparticles spatially organized on dendritic fibrous nanosilica, achieves visible-to-near-infrared absorption through tunable nanogaps and particle-size heterogeneity. Synthesized via a cycle-by-cycle protocol or a scalable one-pot method, it generates dense electromagnetic hotspots that drive efficient light-to-chemical energy conversion under mild conditions. Applications in CO₂ hydrogenation, C-Cl bond cleavage, and acetylene semihydrogenation employ antenna-reactor hybrids such as black gold-Ni and black gold-RuPt, where synergistic interfacial effects enhance hot-carrier lifetimes, near-field intensities, and catalytic selectivity. With a broadband optical response, structural adaptability, and compatibility with diverse catalytic centers, black gold serves as a benchmark plasmonic platform. This Mini-Review outlines its design principles, synthesis, mechanistic insights, and future potential for sustainable, light-driven chemical transformations.