Publications Repository - Gdańsk University of Technology

New rare earth-doped K2Ta2O6 photocatalysts were successfully synthesized by hydrothermal method. The effect of dopant type (Y,Yb,Ho,Pr,Er) and amount of rare earth precursor (2,4,8 and 10 mol%) on the physicochemical and photocatalytic properties of RE-K2Ta2O6 have been investigated. All as-prepared materials were characterized by UV–vis diffuse reflectance spectroscopy, Brunauer-Emmett-Teller specific surface area measurement, scanning electron microscopy with energy dispersive X-ray spectroscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, magnetic susceptometry and photoluminescence emission spectroscopy. The photocatalytic activity under UV–vis light irradiation was estimated in phenol degradation in aqueous phase, toluene removal in gas phase and H2 generation from formic acid solution. The experimental results show that, novel RE-K2Ta2O6 exhibits greatly improved degradation efficiency under UV–vis light irradiation compared with pristine K2Ta2O6. The Er-K2Ta2O6 and Pr-K2Ta2O6, obtained by introducing of 2 mol% of RE ions during synthesis, reveal the highest photocatalytic activity among prepared samples in aqueous phase (33% of PhOH decomposition after 90 min of irradiation) and gas phase (45% of toluene removal after 60 min), respectively. Moreover, both photocatalysts present good stability after subsequent three cycles. The active species trapping test shows that OH and O2− radicals are significantly involved in phenol oxidation under UV–vis light. The amount of H2 evolution increases with addition of Er dopant. The highest H2 production is obtained for 10 mol% Er-K2Ta2O6 after 240 min of UV–vis light irradiation (15.4 μmol/min). Enhanced photoactivity performance can be attributed to incorporation of RE ions at K+ lattice site in RE-K2Ta2O6, probably leading to formation of new RE 4f states below the conduction band of K2Ta2O6 structure. To investigate the localization of RE ions in K2Ta2O6 structure, the band structure and partial density of the states have been investigated. Computer simulations were performed using plane-wave based Vienna ab-initio simulation package with the generalized gradient approximation by Perdew-Burke-Ernzerho. Moreover, inclusion of RE ions in K2Ta2O6 causes predominance of pyrochlore phase formation over perovskite.

Authors

• mgr inż. Anna Krukowska,
• dr inż. Michał Jerzy Winiarski link open in new tab ,
• Judyta Strychalska-Nowak link open in new tab ,
• prof. dr hab. inż. Tomasz Klimczuk link open in new tab ,
• Wojciech Lisowski,
• Alicja Mikolajczyk,
• Henry P. Pinto,
• Tomasz Puzyn,
• Tomasz Grzyb,
• Adriana Zaleska-Medynska