Large Area alpha-Cu2S Particle-Stacked Nanorod Arrays by Laser Ablation in Liquid and Their Strong Structurally Enhanced and Stable Visible Photoelectric Performances

A flexible route is developed for fabrication of large area alpha-Cu2S nanorod arrays (NRAs) on the basis of one-step laser ablation of a copper foil in CS2 liquid. It has been demonstrated that the obtained products are the high temperature phase alpha-Cu2S and consist of the nanorods vertically standing on the Cu foil, exhibiting the array. The nanorods were about 1 mu m in length and around 100 nm in thickness and built by stacking the nearly spherical and < 110 > oriented nanoparticles (NPs) up. Such array can be peeled off from the foil and remain freestanding. Further, it has been found that the ablation duration, the laser power, and the foil surface state are crucial to the formation of the Cu2S NRA. The formation of such oriented NP-stacked Cu2S NRAs is attributed to the laser-induced generation of alpha-Cu2S NPs and the NPs' deposition/oriented connection growth on the surface-vulcanized copper foil. Importantly, the visible photocurrent response of the alpha-Cu2S NRAs is 8 times higher than that of the Cu2S NPs' film with the equivalent thickness and also larger than that of previously reported Cu2S, showing significantly enhanced photoelectric performances. As an application, such NRAs have exhibited markedly enhanced visible photocatalytic activity and highly stable recycling performances, compared with the alpha-Cu2S NPs. Further studies have revealed that the enhanced performances are attributed to the structurally enhanced light trapping effect of the NRAs as well as short and smooth carrier diffusion path in the oriented NP-stacked nanorods. This work provides a new and simple method for fabrication of the large area Cu2S NRAs with high and stable photoelectric performances.