Metal–organic framework materials exhibit significant potential for diverse applications in gas adsorption and separation. We have studied the performance changes of Cu-BTC, Cu-MBTC and Cu-EBTC under different water-containing conditions. GCMC studies shows that, compared with Cu-BTC, the water absorption properties of Cu-MBTC and Cu-EBTC have a certain degree of decline, which is consistent with the experimental results. The incorporation of alkyl groups led to a decrease in the heat of adsorption for both Cu-MBTC and Cu-EBTC when exposed to water. The gas adsorption performance of Cu-BTC, Cu-MBTC and Cu-EBTC exhibits inconsistent variations in gas adsorption performance under water-containing conditions. The addition of coordinated water molecules enhances the ability of Cu-BTC to adsorb CO₂. The capacity of Cu-MBTC with 4 wt% water to adsorb CO₂ increased, but the capacity of Cu-MBTC with 8 wt% water to adsorb CO₂ decreased. The presence of coordinated water molecules reduces the CO₂ adsorption performance of Cu-EBTC. The study of the heat of adsorption explains this phenomenon from the mechanism. At the same time, we found an interesting phenomenon. The existence of trace water molecules can greatly improve the adsorption selectivity of Cu-EBTC to CO₂/N_2, while the pressure and gas ratio have little effect. It can provide more possibilities for the widespread use of MOF in the fields of gas adsorption and separation.

To study the effect of strain engineering on the thermoelectric properties of SnSe, we combined first-principles calculation and Boltzmann transport theory to study the effect of −4% to 4% strain on SnSe thermoelectric properties. Compressive strain enhances the maximum power factor (PF_max) of p-type SnSe from 2.3 to 4.3 mW·m⁻¹·K⁻². Specifically, under a −3% compressive strain, the thermoelectric figure of merit (ZT) experiences a 50% enhancement, increasing from 0.18 to 0.27. Conversely, for n-type, tensile strain leads to a 26% rise in the PFₘₐₓ, from 53.6 to 67.6 mW·m⁻¹·K⁻². Notably, the 4% tensile strain increased the ZT value of n-type SnSe by 123% from 0.66 to 1.47. Importantly, tensile strain effectively reduces lattice thermal conductivity through enhanced phonon scattering, synergistically improving ZT with the enhanced power factor. The results show that strain can effectively improve the thermoelectric properties of SnSe, and that n-type SnSe has great potential in thermoelectric materials.

To elucidate the influence of water on terahertz (THz) spectral responses, terahertz time-domain spectroscopy (THz-TDS) was employed to monitor the thermal decomposition of copper(II) sulfate pentahydrate in this study. Continuous dehydration of the hydrate induces pronounced variations in the THz signal. At the initial stage of thermal decomposition, these changes primarily originate from the evolving state and amount of water confined within the CuSO₄·5H₂O lattice. After detaching from the crystalline framework, the released water molecules do not evaporate immediately; instead, they transiently reside near the copper sulfate as free water. When the temperature reaches approximately 60 °C, a dynamic equilibrium is established between crystalline water and free water. The THz spectral data reveal that the sample exhibits its strongest THz absorption at this temperature. Consequently, the THz signal during decomposition displays a characteristic trend: an initial decrease followed by an enhancement. These findings demonstrate that THz-TDS represents a promising approach for probing the state and content of water, thereby contributing to the development of a powerful analytical tool for fundamental studies in mineralogy.