Revealing the Synergy of Mono/Bimetallic PdPt/TiO₂ Heterostructure for Enhanced Photoresponse Performance

This work reports a synergistic study of a noble metal (NM)/semiconductor hybrid structure featuring a mono/bimetallic PdPt/TiO₂ heterostructure prepared by a facile anodization-hydrothermal process. The electronic interaction between TiO₂ nanotubes (NTs) and mono/bimetallic PdPt nanoparticles (NPs), as well as the bimetallic PdPt interplay, has been thoroughly investigated by various X-ray techniques. Particularly, X-ray absorption near edge structure (XANES) at the Ti L_3,2-edge and O K-edge was employed to understand the NM sensitization effect on the local structure of the TiO₂ host. Meantime, d-charge redistribution within Pd and Pt upon alloying and loading on TiO₂ NTs was disclosed at the Pt L₃-edge and Pd L₃-edge XANES, respectively. Consistent results were given from their corresponding X-ray photoemission spectroscopy (XPS) analysis. In addition, extended X-ray absorption fine structure (EXAFS) at the Pt L₃-edge and Pd K-edge was also performed to unravel the atomic distribution and intermetallic interaction of Pd and Pt upon alloying. Finally, the synergy within the mono/bimetallic PdPt/TiO₂ heterostructure was examined by size, compostion, and structure of the as-attached NM NPs assisted with photoresponse performance analysis.