An in situ fluorine and ex situ titanium two-step co-doping strategy for efficient solar water splitting by hematite photoanodes. Issue 6 (2nd March 2022)

• Record Type: Journal Article
• Authors: Kang, Kyoungwoong; Zhang, Hemin; Kim, Jeong Hun; Byun, Woo Jin; Lee, Jae Sung
• Is Part Of: Nanoscale advances. Volume 4:Issue 6(2022)
• Page Start: 1659
• Page End: 1667
• Publication Date: 2022-03-02
• Subjects: 620.5
• DOI: 10.1039/d2na00029f
• Languages: English
• ISSNs: 2516-0230

Abstract

Abstract : A novel two-step co-doping strategy of in situ F − anion, followed by ex situ Ti 4+ cation promotes the hematite photoanode for water splitting much more effectively than single-step co-doping strategies that are either all in situ or all ex situ . Abstract : A unique two-step co-doping strategy of in situ fluorine doping followed by ex situ titanium doping enhances the performance of the hematite photoanode in photoelectrochemical water splitting much more effectively than single-step co-doping strategies that are either all in situ or all ex situ . The optimized fluorine, titanium co-doped Fe2 O3 photoanode without any cocatalyst achieves 1.61 mA cm −2 at 1.23 VRHE under 100 mW cm −2 solar irradiation, which is ∼2 and 3 times those of titanium or fluorine singly-doped Fe2 O3 photoanodes, respectively. The promotional effect is attributed to the synergy of the two dopants, in which the doped fluorine anion substitutes oxygen of Fe2 O3 to increase the positive charges of iron sites, while the doped titanium cation substitutes iron to increase free electrons. Moreover, excess titanium on the surface suppresses the drain of in situ doped fluorine and agglomeration of hematite during the high-temperature annealing process, and passivates the surface trap states to further promote the synergy effects of the two dopants.