Regulating electron transfer pathway in Au/W18O49 heterostructures by structural design for revealing the photocatalytic mechanism of metal/semiconductor heterostructures

The construction of metal/semiconductor heterostructures is a useful technique for improving the electron-hole separation of Semiconductor Photocatalysts. However, there only are a few studies on the mechanism of electron transfer between metal/semiconductor heterostructures. Therefore, through the intelligent design of the material structure, two metal/semiconductor heterostructures (Au/W18O49 heterostructure) were fabricated with identical composition but different structures by different preparation methods: (1) The heterostructure of Au nanoparticles at the tip of sea urchin W18O49 was achieved through photoreduction method; (2) the heterostructure of Au nanoparticles at the root of sea urchin W18O49 was achieved via chemical reduction method, and their electron transfer paths were studied. The results demonstrated that the two materials went through completely different electron transfer paths, and these different electron transfer path also leads to an opposite set of photocatalytic properties. The heterostructure achieved through photoreduction has the best photocatalytic performance. Nevertheless, the photocatalytic performance of the heterostructure prepared by chemical reduction is far inferior to that of the heterostructure prepared by photoreduction, and even inferior to the original W18O49 sample. Therefore, we believe that the structural characteristics of metal/semiconductor heterostructure have a great influence on the electron transfer path. Our work renders useful information that may facilitate the design of heterostructure photocatalyst based on metal/semiconductors.