Liquid gating membranes with molecular-level smooth liquid lining layers break through the limitations of traditional porous membrane materials in gas transport control. Owing to the stable, self-healing, and reconfigurable properties, liquid gating membranes have shown wide application prospects in microfluidics, intelligent valves, chemical reactions, and beyond. Here, we develop a periodic gas transport control system based on the self-oscillating liquid gating membrane. Under continuous gas injection, the gas–liquid interface is reversibly deformed, enabling self-oscillating behavior for discontinuous and periodic gas transport without the need for any complex external changes to the original system. Meanwhile, our experimental analysis reveals that the periodic time and periodic gas release in the system can be regulated. Based on the cycle stability of the system, we further demonstrate the controllability of the system for periodic droplet manipulation in microfluidics. Looking forward, it will offer new opportunities for various applications, such as pneumatic robots, gas-involved chemical reactions, droplet microfluidics, and beyond.
To explore nanocatalysts with high electro-catalytic performance and less loading of precious metals, efforts have been made to develop electrochemical methods with high spatial resolution at the single nanoparticle level. Herein, a highly sensitive single-nanoparticle coulometry method is successfully developed to study the electrochemical activity and oscillation of single PtTe nanocatalysts. Based on microbattery reactions involving the formic acid electro-oxidation and the deposition of Ag on the single PtTe nanocatalyst surface, this method enables the transition from the undetectable sub-fA electric signal of the formic acid electro-oxidation into strong localized surface plasmon resonance scattering signal of Ag detected by dark-field microscopy. The lowest limiting current for a single nanocatalyst is found to be as low as 25.8 aA. Different trends of activity versus the formic acid concentration and types of activity of the single nanocatalyst have been discovered. Unveiled frequency-amplitude graph shows that the two electrochemical oscillation modes of low frequency with high amplitude and vice versa coexist in a single PtTe nanocatalyst, indicating the abundantly smooth surfaces and defects of nanocatalysts. This conducted study will open up the new avenue for further behavioral and mechanistic investigation of more types of nanocatalysts in the electrochemistry community.
The restructuring of a catalyst under working conditions has been recognized as a critical factor that can significantly impact their performance in recent years. In this study, we investigate the behavior of a highly dispersed Ni supported on TiO 2 (P25) catalyst during the partial oxidation of methane (POM) to produce syngas. Our results reveal a distinct oscillation phenomenon in the catalyst's performance over time. The simultaneous oscillations of rapid deactivation and activation are observed, while the catalyst remains active for continuous POM reaction. Comprehensive characterizations suggest that this deactivation is not caused by traditional deactivation mechanisms with coke formation or Ni sintering. The formation of inactive NiTiO 3 results in catalyst deactivation, which is formed between Ni and TiO 2 support in the reductive atmosphere of POM products under high temperature due to strong metal-support interaction (SMSI). The simultaneous presence of oxidative and reductive atmospheres of the reactants and products in the POM reaction leads to the generation or demise of NiTiO 3 . The dynamic change of the Ni active sites during the in-situ reaction leads to the oscillation of the catalytic activity. This study sheds new light on the importance of SMSI in understanding the behavior of catalysts under working conditions.
危险品化学品经营许可证（带存储）