Mn⁴⁺ activated fluoride phosphors have been considered as highly promising red component for warm white light-emitting diodes in recent years. In this paper, we successfully prepared the K₂TiF₆: Mn⁴⁺ red phosphors in H₃PO₄/KHF₂ liquid instead of the hypertoxic HF liquid. The impact factors, such as the amount of F source, the reaction temperature, reaction time, and the luminescence mechanism are investigated in detail. We found that K₂TiF₆: Mn⁴⁺ shows pure red emission and can be excited by blue lights, which can perfectly match the InGaN chip based white light-emitting diodes. Most importantly, K₂TiF₆: Mn⁴⁺ exhibits excellent quenching behavior and shows small color shift in the temperature range of 300–475 K. Our researches could provide a green synthetic strategy to obtain the K₂TiF₆: Mn⁴⁺ phosphors and contribute to the optimization of red phosphors for white light-emitting diodes.

The development of highly sensitive gas sensors for toxic industrial gases (TIGs) is paramount for environmental monitoring and public safety. Here, the first-principles calculations were employed to systematically investigate the potential of Pt- and Rh-decorated InS (Pt-InS and Rh-InS) monolayers as advanced gas sensing materials for the five TIGs (SO₂, NH₃, NO, CO, and NO₂). The results reveal that Pt and Rh atoms can be stably anchored at the InS monolayer, inducing significant modulation of its electronic properties. The Pt-InS system exhibits strong chemisorption of NH₃ and CO, while the other TIGs interact via physisorption. In contrast, the Rh-InS monolayer demonstrates strong chemisorption and distinct electronic responses to all five gases, driven by robust hybridization between the Rh-d and TIG-p orbitals. Based on comprehensive analyses of sensitivity and recovery time, Rh-InS is identified as a theoretically promising candidate for a reusable SO₂ sensor at room temperature, boasting a calculated rapid theoretical recovery time of 2.20 s. The Pt-InS system, conversely, shows potential for high-temperature NH₃ sensing. Our findings highlight the exceptional and tunable gas sensing capabilities of Pt- and Rh-decorated InS monolayers, offering a theoretical foundation for designing InS-based sensing devices.