Structural and Optical Interplay of Palladium-Modified TiO₂ Nanoheterostructure

Abstract

The electronic structure and optical properties of Pd modified TiO 2 nanotubes (NTs) with vertically aligned nanotubular structure grown by a two-step electrochemical anodization method have been studied using X-ray spectroscopy. X-ray Absorption Near Edge Structure (XANES) at Ti L 3,2-and O K-edge has been used to investigate the TiO 2 NTs before and after Pd modification. It is found that Pd nanoparticles (NPs) are uniformly coated on the NTs' surface.

Tracking the Local Effect of Fluorine Self-Doping in Anodic TiO2 Nanotubes

“…Energy dispersive X-ray (EDX) analysis ( Figure S1 in the Supporting Information) of APNT shows its dominant Ti and O components as well as ∼14.5% F (Table S1). Upon thermal annealing in ambient air at 450°C to initiate anatase crystallization ( Figure S2), 31 the NT morphology (Figure 1c,d) remains intact although most of the F − ions are driven out with a remainder of 1.61% (Table S1) in the TiO 2 matrix.…”

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

“…The preparation of highly ordered TiO 2 NTs (TNTs) using an electrochemical anodization procedure has been previously reported. , Briefly, a homemade two-electrode cell was utilized for Ti anodization where the Ti foil (0.1 mm thick, Goodfellow) with a size of 2 cm × 0.5 cm was employed as the anode and a Pt wire was used as the cathode. An ethylene glycol-based electrolyte with the inclusion of 0.3 wt % NH 4 F (ACS, 98% min, Alfa Aesar) and 2 vol % H 2 O was prepared for the anodization experiment.…”

“…Mono/bimetallic NM NPs were deposited onto anatase TNTs using a facile hydrothermal method . Anatase TNTs together with a 15 mL bath solution including 150 mg of polyvinylpyrrolidone (PVP, M w ≈ 55000, Sigma-Aldrich), 56 mg of NaI (ACS, 99.5%, Sigma-Aldrich), and a certain amount of NM precursor(s) were loaded into a 50 mL Teflon-lined stainless-steel autoclave and heated under sealing for 2 h at 180 °C.…”

“…Among these, the sensitization of TiO 2 with NM (i.e., Pt, Pd, Au, and Ag) nanoparticles (NPs) recently has attracted enormous attention. Indeed, research on the NM/TiO 2 hybrid structure has made a prominent process toward solar energy utilization. − The design of this approach is not only because NM can enhance the photoabsorption due to its localized surface plasma resonance − but also because the equalized Fermi level energy of the NM/TiO 2 heterojunction is lower than the conduction band energy of TiO 2 , which allows the efficient electron transfer from the conduction band of TiO 2 to the attached NM NPs. Meantime, the formation of the Schottky barrier between TiO 2 and the attached NM NPs (Figure S1) would block the electron back-transfer, resulting in efficient e – /h + separation.…”

“…To this end, we here report a facile synthesis and comprehensive characterization of the bimetallic PdPt/TiO 2 hybrid structure. A one-dimensional (1D) TiO 2 nanotube (NT) prepared from electrochemical anodization was selected as a host structure for the secondary NM deposition due to its unique geometry and alignment over other TiO 2 forms such as nanoparticle, nanowire, and nanobelt. , Then, a facile hydrothermal process was utilized over sol–gel, , photodeposition, , and electrochemical , synthesis, to prepare the NM/semiconductor hybrid structure, which demonstrates a better control over the size, composition, and quantity of as-deposited NM NPs . Afterward, X-ray techniques were applied on the mono/bimetallic PdPt/TiO 2 heterostructures to reveal the electronic and structural interplay associated with their photoresponse performance.…”