The Journal of Physical Chemistry C最新文献

Self-recoverable mechanoluminescence (ML) has demonstrated broad applications in mechanosensory optoelectronic devices based on pressure- and rate-dependent emission performance. However, understanding the coupled effect of pressure and rate on the ML kinetics remains elusive, limiting the design of time-characterized ML-based optoelectronic devices. Here, we show that SrZn₂S₂O:Mn²⁺ exhibits an oscillatory ML behavior with a series of sharp emission peaks in a time-dependent ML curve under rapid compression from 0.1 to 11.0 GPa at critical rates of ∼1.7–4.7 GPa/s, distinct from the ML kinetics under decompression in which the ML curve presents broad emission peaks. The X-ray diffraction measurement shows that the SrZn₂S₂O matrix is stable up to ∼14.6 GPa above which it transforms to a new structure. Photoluminescence spectroscopy shows that SrZn₂S₂O changes monotonically in emission intensity and wavelength in the pressure range of 0.1–8.2 GPa. By combining the experimental results with the piezoelectric detrapping model, we suggest that the oscillatory ML behavior under rapid compression may result from the multiple-cyclic processes of the piezoelectrically induced excitation of the luminescent activators, indicating the intrinsic response to rapid compression. The rate-dependent distinct ML kinetics may be conducive to the design of ML devices with temporal characteristics.

The synthesis of ZIF-25 was successfully optimized by using acetic acid as a modulator agent, yielding a highly crystalline material. The product exhibits significant porosity, thermal stability up to 300 °C, and hydrophobicity, making it ideal for use in lyophobic heterogeneous systems (LHSs). Notably, the crystal structure of ZIF-25 was refined for the first time using the Rietveld method and fully reported in space group Pm3̅m. Energetic performance evaluation in intrusion–extrusion experiments shows that the “ZIF-25–water” system dissipates mechanical energy with adsorbed and released energies of ∼15–19 and ∼10 J g^–1, respectively. These features make it an LHS with shock-absorber characteristics. The study highlights that the energetic behavior of ZIFs is topology-dependent, with RHO-type ZIFs such as ZIF-25 and ZIF-71 showing shock-absorber properties, while SOD-type ZIFs (like ZIF-8) exhibit spring-like behavior. Post-experiment characterizations, performed by X-ray diffraction, nitrogen adsorption at 77 K, and scanning electron microscopy, indicate moderate and pressure-dependent degradation when the material is subjected to pressurized water intrusion.

This study establishes a theoretical framework to elucidate the impact of gas bubble evolution dynamics on the reaction overpotentials in electrolytic hydrogen and oxygen production. By distinguishing between ohmic, activation, and concentration overpotentials, we formulate governing equations to determine the influence of gas bubble growth and detachment on each overpotential component. Additionally, we employ SHapley Additive exPlanations (SHAP) analysis to interpret the patterns identified by a regression neural network trained on our analytical equations. Our findings indicate that gas bubble evolution dynamics impact reaction overpotentials to different degrees, leading to divergent escalation rates and requiring targeted improvement strategies. We therefore systematically investigate the impact of key parameters influencing the gas bubble evolution dynamics such as the electrode surface wettability, the electrolyte concentration and the temperature on mitigating reaction overpotentials. Measures, such as enhancing the electrode hydrophilicity from 90 to 160°, reduces the activation and concentration overpotentials by up to 54.0% and 79.3%, respectively. Moreover, by increasing the electrolyte molarity from 0.5 to 1 M, ohmic and concentration overpotentials can be reduced by 47.1% and 72.1%, respectively, with diminishing performance returns beyond 2 M. Higher temperatures result in mild to moderate decreases across all overpotential components by improving electrolyte conductivity and mass transfer. In summary, this analysis provides valuable insights not only for optimizing electrolytic hydrogen and oxygen production devices, but it also offers the opportunity to transfer gained insights into other gas-evolving electrochemical systems and supports their optimization toward higher energy conversion efficiencies.