Preparation of Pt@Au Hollow Nanobipyramid Heterostructures for Effective Photocatalytic Degradation

Bimetallic heterogeneous nanomaterials are widely used in photocatalysis to degrade toxic organic compounds. By design of the morphological characteristics of nanomaterials, their catalytic degradation properties can be better exerted. Here, the controllable preparation of Au and Pt bimetallic heterogeneous nanomaterials is achieved by a water phase synthesis method. By regulating the solution environment during growth processes carefully, the growth position of Pt on the Au nanobipyramids (Au NBPs) can be precisely controlled, and two different nanostructures are prepared, which are called Au@Pt nanobipyramids (Au NBP@Pt) and pyramid-like Au/Pt nanodumbbells (P-Au/Pt), corresponding to Pt nanoparticles on the surface and the tips of the Au NBPs. Based on Au NBP@Pt nanostructures, hollow Pt nanocages are obtained by etching Au. Then, Au is grown on the surface of Pt nanocages, and the Pt@Au hollow nanobipyramids (Pt@Au hollow NBPs) are prepared. We investigate the photocatalytic reduction rates of four nanostructures and find that Pt@Au hollow NBPs have the fastest catalytic reduction rate compared to other nanostructures. The reaction rate constant k of Pt@Au hollow NBPs is 7.84, 4.46, and 17.99 times that of P-Au/Pt, Au NBP@Pt, and R-Au/Pt, respectively. We carry out a comprehensive analysis of this result. We find that compared to the nonhollow structures, Pt@Au hollow NBPs have two strong plasmon resonances, which indicate electric resonance and magnetic resonance, resulting in strong light absorption and efficient electron transfer rate. In addition, Au@Pt hollow NBPs also have a large specific surface area. The convergence of the aforementioned reasons collectively contributes to the significantly increased catalytic rate. Our work provides a new approach for preparing hollow bimetallic heterogeneous nanomaterials, and the technology has great potential in photocatalysis applications and environmental governance.