Understanding the anatase–rutile phase junction in charge separation and transfer in a TiO₂ electrode for photoelectrochemical water splitting

Abstract

The key to phase junctions for efficient charge separation is to consider both the phase alignment and interface structure.

Photoelectrode for water splitting: Materials, fabrication and characterization

“…Changing the atmosphere (e.g., O 2 , N 2 or NH 3 ) can produce different metal oxides and nitride, such as TiO 2 , WO 3 , ZnO, Ta 3 N 5 , etc. [81][82][83][84]. For PLD, it is a top-down film fabrication method where the target is well-prepared semiconductor and the film is formed by depositing the tiny particles from the target onto the substrate (Fig.…”

Structural‐Phase Catalytic Redox Reactions in Energy and Environmental Applications

“…By evaluating the band position, it was concluded that the charge recombination rate was higher in type A and type C than in type B, resulting in improved photocurrent density with type B, as shown in Figure . Likewise, the phase junction between the type B system and TiO 2 ‐AR (calcined slowly with oxygen) exhibited higher performance in terms of charge separation and migration . Apart from this finding, the interface between the type B system and TiO 2 ‐dAR (calcined with oxygen in two steps) slightly enhanced the charge‐carrier separation and migration to the reactive sites because of the presence of interfacial dislocations.…”

“…To obtain unidirectional charge‐carrier migration and reduce the number of defect sites at the interface, it is thus necessary to tune the phase alignment configuration, which would increase the PEC‐OWS performance. Three types of anatase and rutile phase alignment configurations have been considered as photoanodes in the PEC‐OWS system: random alignment of various phases (type A), rationally ordered phase alignment (type B), and ordered phase alignment in a reverse configuration (type C) . By evaluating the band position, it was concluded that the charge recombination rate was higher in type A and type C than in type B, resulting in improved photocurrent density with type B, as shown in Figure .…”

“…Apart from this finding, the interface between the type B system and TiO 2 ‐dAR (calcined with oxygen in two steps) slightly enhanced the charge‐carrier separation and migration to the reactive sites because of the presence of interfacial dislocations. In such a situation, the CB represents an energy barrier for excess minority carriers so that electrons can migrate to the reactive sites, as shown in Figure …”

“…The dotted arrow indicates the undesirable interface trapping or recombination process. c–f) Adapted with permission . Copyright 2016, The Royal Society of Chemistry.…”