First Principles Study on the Features of Ca_xSr_2−xTa₂O₇ (x = 0, 1) as a Photocatalytic Material

Abstract

With hydrogen as one of the energetic vectors craved for use in the future, the successful de-carbonization of the energy sector will require an increase in hydrogen production from renewable resources. Materials that are able to catalyze the water-splitting reaction through sunlight absorption have been widely studied as an adequate solution for green hydrogen generation. Among the proposed tantalum-based oxide materials, Sr2Ta2O7 displays moderate photocatalytic activity. Aiming to improve the photocatalytic properties by means of compositional modifications, this work presents a DFT study of the Sr substitution with Ca. The structural, energetic, and electronic features of the phases of CaxSr2−xTa2O7 (0 < x < 1) have been examined. The computational results utilizing the SCAN functional show that there is a slight decrement in the band gap value (from 3.65 eV for x = 0 to 3.50 eV for x = 1) concomitant to a minor distortion of the crystal structure.

Keywords

• Sr₂Ta₂O₇
• green hydrogen
• photocatalysis
• water splitting
• DFT