https://doi.org/10.1140/epjb/s10051-025-01093-z
Research - Condensed Matter
Rb2MBr6 vacancy-ordered perovskites (M = W4+: 5d2, Re4+: 5d3, Os4+: 5d4, Ru4+: 4d4): harnessing light, heat, and spin for a greener future
1
Laboratory of Quantum Physics of Matter and Mathematical Modeling (LPQ3M), Mascara University, Mascara, Algeria
2
Center for Innovation and Entrepreneurship, Imam Mohammad Ibn Saud Islamic University (IMSIU), 11623, Riyadh, Kingdom of Saudi Arabia
3
Chemistry Department, Faculty of Science, Taibah University, Al-Madinah, Saudi Arabia
Received:
7
August
2025
Accepted:
14
November
2025
Published online:
23
November
2025
The escalating global climate crisis, driven by greenhouse gas emissions, necessitates advanced sustainable energy technologies, including hydrogen production, CO2 photoreduction, and waste heat recovery. This study explores the vacancy-ordered double perovskites Rb2MBr6 (M = W4+: 5d2, Re4+: 5d3, Os4+: 5d4, Ru4+: 4d4) as promising materials for these applications, leveraging their enhanced stability and tunable properties. Employing density functional theory (DFT) with spin–orbit coupling (SOC) and the Tran-Blaha modified Becke-Johnson (TB-mBJ) potential in the WIEN2k framework, we investigate structural stability, electronic band structures, optical absorption, photocatalytic reactivity, and thermoelectric performance. Results reveal cubic Fm-3m structures with lattice constants of 10.36–10.97 Å, negative formation energies (−1.26 to −3.60 eV), and mechanical ductility (B/G > 1.75), confirming thermodynamic and structural robustness. Band gaps range from 1.54 eV (Rb2RuBr6) to 2.97 eV (Rb2WBr6), with half-metallic ferromagnetic behavior enhancing spintronic potential. Optical absorption coefficients (4.32–21 × 105 cm−1) and low exciton binding energies (18.3–27.3 meV) support efficient photocatalysis, with Rb2WBr6 showing balanced band edges for water splitting (EVB = 1.48 V, ECB = −1.48 V vs. NHE). Thermoelectric figures of merit (ZT) reach 1.325 (Rb2ReBr6) at 300 K, declining to 1.275 at 1000 K, surpassing Bi2Te3. These findings establish Rb2MBr6 as a versatile platform for clean energy technologies, with future experimental validation poised to accelerate their deployment.
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Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
