Controlled Release of H2S and NO through Air-Stimulated Anion Exchange

H₂S and NO are gas molecules with physiological activities; solid materials that release these gases under safe and ubiquitous stimuli offer broad medical applications. Herein, we report solid materials that autonomously release ppm-level H₂S or NO under air. HS⁻ or NO₂⁻ incorporated in the interlayer of layered double hydroxide (LDH), a clay mineral, is protonated by CO₂ and H₂O, yielding H₂S or HNO₂. HNO₂ generates NO through disproportionation or reduction. Moreover, another NO-release method employs solid mixtures of NO₂⁻-incorporated LDH and FeSO₄, wherein wet air triggers NO₂⁻ reduction with Fe²⁺ through anion exchange between NO₂⁻ and SO₄²⁻. A potential application of the air-stimulated gas release system is demonstrated by creating a portable and battery-free NO inhaler for emergency treatment of respiratory distress.