Interfacial self-assembly of nanoZnO@multiporphyrin array hybrids as binary light-sensitizers for photocurrent generation and photocatalytic degradation of organic pollutants

Abstract

Both porphyrins and nanoscale ZnO semiconductors (nanoZnO) are important eco-friendly light-sensitizers and photocatalysts in academic researches and industrial applications. Here, ultrathin films of multiporphyrin arrays were constructed on the surface of nanoZnO to produce binary hybrids based on the coordination reaction of Pd(II) ions and tetrapyridylporphyrin (TPyP). The hybrids of nanoZnO@(Pd–TPyP)n as-produced displayed an improved absorption ability from 200 to 700 nm and an effective energy transfer between the multiporphyrin arrays and nanoZnO cores. Benefit from such a synergistic effect, their photocatalytic performance was largely improved as compared with that of the original porphyrins and nanoZnO particles. Particularly, under only visible light radiation, the photocurrent density of nanoZnO@(Pd–TPyP)n hybrids was approximately 25 times stronger and the photocatalytic efficiency on the degradation of Rhodamine B was over 10 times higher as compared with that of the original nanoZnO particles. Finally, because the multiporphyrin arrays were anchored on the nanoZnO’s surfaces via the covalent and coordinative bonding, the present nano-hybrids displayed not only structural controllability at the molecular level but also well stability, reusability, and recyclability as the heterogeneous photocatalysts.