Probing the role of silver and gold based double perovskite halide oxides for optoelectronic and photocatalytic applications

Abstract

Double perovskite halide oxides have shown great potential in various optoelectronic and photocatalytic applications due to their unique properties. Based on density functional theory (DFT), this study investigates the structural, mechanical, electronic, optical and photocatalytic properties of silver and gold based double perovskite halide oxides Ba₂(Ag/Au)IO₆. The Full-potential linearized augmented plane wave (FP-LAPW) method is used, executed in WIEN2k simulation code. The calculated structural parameters are in good agreement with the experimental results. Both these perovskite compounds exhibit the face centered cubic structure according to the Goldschmidt tolerance factor t_o and octahedral factor μ_o criteria of cubic structure formation. The negative values of formation enthalpy H_f, the elastic properties, and mechanical properties of these compounds demonstrate their thermodynamic and mechanical stability. The band gap values of 2.30(2.07) eV for Ba₂AgIO₆(Ba₂AuIO₆) compounds are estimated by using Perovskite modified Becke-Johnson potential (P-mBJ) plus Hubbard parameter U, revealed significant agreement with the reported values. The observed reduction in the band gap of Ba₂AuIO₆ as compared to Ba₂AgIO₆ is due to the increase in atomic radii of Au over Ag. Furthermore, these compounds possess a direct band gap nature and exhibit promising optical behavior in ultraviolet region. The characteristic optical parameters of these compounds indicate their competency for optoelectronic applications. Moreover, the straddling of standard redox potential within the valence and conduction band edge potentials make them an excellent candidate for hydrogen production from photocatalytic water splitting.