Reversible spin-state switching triggered by humidity capture-release cycle under ambient condition

Combining the fascinating advantages of atmospheric humidity with the phenomenon of spin-state switching (SSS) materials represents an attractive way of triggering the reversible SSS under ambient conditions. In this work, the occurrence of the reversible SSS triggered by the humidity capture/release cycle without the addition of external energy was achieved by mixing composite gels with the two-dimensional ferrous complex. A linear relationship between humidity absorption amounts and the color of the composite gel was established, which facilitates the manufacture of a novel SSS device. This work has provided a new design strategy to motivate SSS performance and may open the way for practical applications of SSS.