First Principles Study on the features of Sr_2-xA_xTa₂O₇ (A = Ba, Ca) as photocatalytic materials

Hydrogen could become one of the energetic vectors widely used in the future. However, hydrogen is normally produced from non-renewable sources, which is a problem regarding the decarbonization of energy generation. Green hydrogen i.e., hydrogen obtain from renewable sources, has only been 1% of total hydrogen generated in the last years [1]. As a means of incrementing this percentage, the generation of H₂ from the dissociation of the water molecule (through electrolysis, photocatalysis, or thermolysis) has emerged as an adequate solution.

Materials that are able to catalyze water-splitting reaction through sunlight absorption has been widely studied [2]. Among the proposed oxide materials, Sr₂Ta₂O₇ displays photocatalytic activity, although its large band gap (4.6 eV) restricts the light absorbance to the ultraviolet region [3]. Several works point to a decrease in the band gap thanks to compositional modifications [4]. Density Functional Theory (DFT) is a powerful tool that allows us to acknowledge the factors behind the named modifications without the necessity of synthesizing the studied materials. In this work, DFT calculations have been performed to study new phases with general formula Sr_2-xA_xTa₂O₇ (A = Ba, Ca). Structural, energetic, and electronic features have been examined through these calculations.

References

[1] Z. Abdin, A. Zafaranloo, A. Rafiee, W. Mérida, W. Lipiński, y K. R. Khalilpour, Renew. Sustain. Energy Rev. 2020, 120, 109620.

[2] F. E. Osterloh, Chem. Mater. 2008, 20, 35.

[3] A. Kudo, H. Kato, y S. Nakagawa, J. Phys. Chem. B 2000, 104, 571.

[4] K. Y. Kim, T. H. Eun, S.-S. Lee, y U. Chon, Resour. Process. 2009, 56, 3, 138.