The intrinsic low lattice thermal conductivities originates from the complex anion bonding environment make quaternary chalcogenides potential thermoelectric materials. Here, the bonding environment of Se atom in Cu_2.1Mn_0.9SnSe₄ is further regulated by substituting Mn²⁺ with equimolar pairing elements (Ag⁺ and In³⁺). The increase in both bond length and angle, together with the reduction in bond strength of Ag–Se and In–Se bonds, cause the doped samples to display strong anharmonicities (γ ~ 1.84–2.04). And the weakened bond strength also lower the sound velocities. Consequently, the κ_L of the doped samples is effectively constrained, achieving a minimum value of 0.55 W·m⁻¹·K⁻¹ at 673 K in x = 0.10 sample. Ultimately, a zT value of 0.53 at 673 K is attained in x = 0.10 sample. The modification of bonding environment around anion is considered as an effective mean to optimize the thermoelectric performance of quaternary chalcogenides.

Because the volatile content of isoamyl alcohol increases sharply on the seventh day of wheat mildew infection, isoamyl alcohol can be used as an early biomarker of wheat mildew infection. Currently, only a few sensors for isoamyl alcohol detection have been reported, and these sensors still suffer from low sensitivity and poor moisture resistance. Herein, the isoamyl alcohol sensitivity of 5 at% Er@LaFeO₃ (ELFO) was enhanced by loading Ag nanoparticles on the surface of the ELFO microspheres, while the optimal operating temperature was reduced. The moisture resistance of Ag/ELFO was improved by the incorporation of g-C₃N₄ nanosheets (NSs) on the surface of Ag/ELFO through electrostatic self-assembly. Given the requirements for practical applications in grain granaries, the sensing behavior of a Ag/ELFO-based sensor incorporating g-C₃N₄ NSs at 20% relative humidity (RH) was systematically studied, and the sensor demonstrated excellent repeatability, long-term stability, and superior selectivity (791 at 50 ppm) for isoamyl alcohol with a low limit of detection (LOD = 75 ppb). Furthermore, the practical results obtained for wheat at different mildew stages further confirmed the potential of the g-C₃N₄/Ag/ELFO-based sensor for monitoring the early mildew stage of wheat. This work may offer guidance for enhancing the moisture resistance of gas-sensitive materials through the strategy of employing composite nanomaterials.