Non-metal fluorine doping in Ruddlesden-Popper perovskite oxide enables high-efficiency photocatalytic water splitting for hydrogen production

Perovskite oxides have been extensively investigated as catalysts for solar water splitting to generate hydrogen (H-2) due to the easily tuned band gap, distinct optical/chemical properties and superior structural/compositional flexibility. Cation doping is widely used to boost the photocatalytic activity of perovskite oxides while the anion doping into the oxygen (O)-site of perovskite oxides is less investigated. Herein, we present a non-metal fluorine (F-) doping strategy to improve the photocatalytic activity of Ruddlesden-Popper Sr2TiO4 perovskites for H-2 evolution reaction (HER). By optimizing the F- doping amount in Sr2TiO4-xFx, the highest H2 generation rate of 282 mu mol/h/g is achieved by Sr2TiO3.97F0.03 under full-range sunlight illumination (lambda >= 250 nm), which is 44% larger than that of Sr2TiO4 (195 mu mol/h/g). Such enhancement in the photocatalytic HER activity of Sr2TiO3.97F0.03 can be assigned to the increased surface oxygen vacancy amount, suppressed charge carrier recombination, more negative conduction band position as well as well-balanced band gap energy, particle size, and specific surface area induced by the F- doping. Our current study presents a facile and effective strategy for the future design of highly efficient catalysts for solar water splitting. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

In this study, a non-metal fluorine (F-) doping strategy was utilized to enhance the photocatalytic activity of Ruddlesden-Popper Sr2TiO4 perovskites for H-2 evolution reaction (HER). By optimizing the F- doping amount, the highest H2 generation rate was achieved by Sr2TiO3.97F0.03, which showed a 44% enhancement compared to Sr2TiO4. The improved photocatalytic activity of Sr2TiO3.97F0.03 can be attributed to the effects of F- doping on surface oxygen vacancies, charge carrier recombination, conduction band position, band gap energy, particle size, and specific surface area.