A Heterojunction Design of Single Layer Hole Tunneling ZnO Passivation Wrapping around TiO2Nanowires for Superior Photocatalytic Performance

Abstract

Nanostructured hybrid heterojunctions have been studied widely for photocatalytic applications due to their superior optical and structural properties. In this work, the impact of angstrom thick atomic layer deposited (ALD) ZnO shell layer on photocatalytic activity (PCA) of hydrothermal grown single crystalline TiO2 nanowires (NWs) is systematically explored. We showed that a single cycle of ALD ZnO layer wrapped around TiO2 NWs, considerably boosts the PCA of the heterostructure. Subsequent cycles, however, gradually hinder the photocatalytic activity (PCA) of the TiO2 NWs. Various structural, optical, and transient characterizations are employed to scrutinize this unprecedented change. We show that a single atomic layer of ZnO shell not only increases light harvesting capability of the heterostructure via extension of the absorption toward visible wavelengths, but also mitigates recombination probability of carriers through reduction of surface defects density and introduction of proper charge separation along the core-shell interface. Furthermore, the ultrathin ZnO shell layer allows a strong contribution of the core (TiO2) valence band holes through tunneling across the ultrathin interface. All mechanisms responsible for this enhanced PCA of heterostructure are elucidated and corresponding models are proposed.

Improved photocatalytic hydrogen production from methanol/water solution using CuO supported on fluorinated TiO2

“…(B)). The modified Kubelka‐Munk equation was used because this is a method widely used for the determination of Eg values for the heterojunctions based in TiO 2 as has been claimed by other authors . The band gap values for the TiO 2 reference and the TF powder were 3.01 and 2.98 eV, respectively.…”

“…The modified Kubelka-Munk equation was used because this is a method widely used for the determination of Eg values for the heterojunctions based in TiO 2 as has been claimed by other authors. [16][17][18][19] The band gap values for the TiO 2 reference and the TF powder were 3.01 and 2.98 eV, respectively. As can be seen, the fluorination of the TiO 2 sample does not significantly affect the optical properties of the semiconductor.…”

Synthesis of Phase Pure Hexagonal YFeO3 Perovskite as Efficient Visible Light Active Photocatalyst

“…The narrower band gap energy allows the hexagonal phase to harvest the visible light more efficiently. Additionally, based on the XPS analysis, the higher amount of Y in orth-900 may lead to a thicker Y2O3 coating, which hinders the tunneling of holes, resulting in a higher electron-hole recombination rate [42]. As a result, the order of the photocatalytic activity follows the order hex-675 > hex-700 > orth-800 > orth-900.…”

Highly efficient UV-sensing properties of Sb-doped ZnO nanorod arrays synthesized by a facile, single-step hydrothermal reaction

“…3(c), the O 1s peak of the undoped ZnO NRA is deconvoluted into two Gaussian curves corresponding to ZnO lattice oxygen (530.5 eV) and oxygen vacancies (531.8 eV), respectively. 43 Oxygen vacancies are natively generated in pristine ZnO nanorods during growth or vacuum annealing treatment, following the reaction formula:…”