Photoinduced Conversion of Cu Nanoclusters Self-Assembly Architectures from Ribbons to Spheres

Two-dimensional (2D) nanomaterials have attracted much attention because of the unique layered structures and charming properties in many applications. However, with respect to stimulus-responsive 2D nanomaterials, the rigidity of most 2D nanostructures sheds doubt on achieving morphology response. In this paper, a photoresponsive 2D nanostructure is fabricated on the basis of the self-assembly of ultrasmall Cu nanoclusters (NCs) in colloidal solution. The Cu NCs are foremost decorated by the capping ligands with photoresponsive azobenzene (Azo) groups and by virtue of the flexibility of self-assembly techniques to produce nanoribbons. Because the ribbons are composed of individual NCs rather than a rigid whole, the ultraviolet (UV)-induced Cu NCs disassembly permits achieving morphology transformation. The disassembly of Cu ribbons is controlled by the Cu NCs rather than the surface ligands. However, the disassembled Cu NCs will reassemble into spheres if they are coated with Azo groups. The electrocatalytic performance of Cu self-assembly ribbons and spheres in oxygen reduction reaction is further compared. The ribbons show better catalytic activity than the spheres.