Oriented Attachments and Formation of Ring-on-Disk Heterostructure Au–Cu₃P Photocatalysts

Oriented attachments have been extensively studied as an effective method for the formation of large crystals from seed nanocrystals. However, this has been limited mostly to seeds of single-phase materials. In contrast, in this work, oriented attachment of two types of nanocrystals with differences in size, shape, phase, and physical as well as chemical properties is reported. Noble metal (Au) nanoparticles were observed to be crystallographically oriented along the preferred direction on semiconducting Cu 3 P disks and further annealed to obtain intriguing ring-on-disk metal–semiconductor heterostructures. This was triggered using PH 3 gas, which bridged the metal Au particles and Cu 3 P disk. The phosphine chemistry underlying the formation of such heterostructures was elucidated by carrying out several control reactions and analyzing the intermediate products. Because of their optically active nature and dual plasmon effects, these heterostructures were applied as photocatalyst for hydrogen evolution from water, and their efficiency was evaluated.