One‐Step Electrochemical Fabrication of 3D Gold Nanotrees with Enhanced Broadband Plasmonic Excited Carriers for Photoelectrochemical Reactions

Plasmonic nanostructures that generate hot carriers and induce catalytic chemical transformations are ideal candidates for solar energy utilization. However, the existing nanostructures require multistep synthesis procedures and generate fewer hot carriers due to their narrow resonance region and limited hotspots, restricting their usage in plasmonic catalysis. Inspired by the light‐harvesting behavior of the trees, the current work reports a one‐step fabrication strategy via electrodeposition for direct anisotropic growth of the 3D gold nanotrees with tunable size, branches, and height. The as‐synthesized nanostructures with broadband light absorption and plentiful hotspots can significantly foster hot carrier generation. The improved hot electron generation of 3D gold nanotrees is confirmed by in situ surface‐enhanced Raman spectroscopy for the dimerization reaction of 4‐nitrothiophenol. The energetic hot holes generated by the 3D gold nanotrees facilitate water oxidation and exhibit 18.6 times higher catalytic efficiency than Au film under 625 nm. Meanwhile, the photoelectrochemical catalysis of 3D gold nanotrees shows better performance compared with conventional Au nanospheres. This work opens up a promising avenue for fundamental studies of plasmonic catalysis via a wide variety of 3D gold nanotrees.