Tensile strain effect on electronic and optical properties of lead-free vacancy-ordered double perovskites Cs2PtI6 for photocatalytic applications

The conversion of solar energy into chemical fuel poses a considerable challenge within the realm of sustainable energy. Recently vacancy-ordered double perovskite materials have attracted much consideration as promising entities in the domain of solar energy capture. Based on DFT calculation, optoelectronic and photocatalytic properties of Cs₂PtI₆ under strain effect were investigated. This Cs₂PtI₆ compound shows indirect band gap (Г–X) of 1.41 eV, and under applied tensile strain this band gap value widens to 1.998 eV. From optical properties calculation, the influence of strain is evident in the reduction of R (0) from 16.8% for unstrained Cs₂PtI₆ to 12.5%. Notably, the obtained loss energy within the visible range remains obviously small (below 0.1) in the energy spectrum below 3 eV, showcasing minimal energy loss in this material under tensile strain. Furthermore, this investigation establishes the viability of 6% applied strain to highlighting Cs₂PtI₆ as a candidate for solar water splitting, enhancing its efficacy in H₂O oxidation for pH levels ranging from 6 to 11 compared to the unstrained form. Moreover, the application of 6% tensile strain significantly improves the efficiency of Cs₂PtI₆ as a photocatalyst for converting CO₂ into valuable compounds like C₂H₄, CH₃COOH, CH₄, and graphite C, particularly notable at pH = 7. These findings highlight the efficiency of strain engineering in advancing the performance of Cs₂PtI₆ for solar-driven chemical transformations, representing a significant stride in sustainable energy research.

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