This paper mainly studies the droplet breaking behavior in contracted pore throat microchannels. The droplet breaking process consists of four stages: extrusion, stretching, sub-droplet growth and fracture. The effects of interfacial tension and dispersed phase viscosity on droplet rupture were investigated. And changes in the localized pressure drop during droplet breaking. In order to understand the droplet deformation mechanism more deeply, we have successfully used micro-particle image velocimetry (micro-PIV) to describe the velocity distribution in the flow. The results show that the fluid characteristics of the continuous phase dominate the droplet deformation and fragmentation in the microdevice geometry. In addition, we built a model based on Taylor's analogy to predict the size of the child droplet formed when the parent droplet is broken during deformation, and compared it with the experimental data. The predicted model and the experimental data show a satisfactory agreement in terms of approximation.

Ammonia plays an irreplaceable role in agricultural production and also is an important chemical raw material and energy carrier. Developing a catalyst for the electrochemical NO₃⁻ reduction reaction (NO₃RR) to synthesize ammonia is crucial for energy, food security and pollution control. Herein, by adjusting the Cu/Ni ratio, we report a simple impregnation and calcination method to synthesize a N-doped bamboo-like carbon nanotube (CNT)-encapsulated CuNi alloy catalyst (Cu₇Ni₃-CNT). Cu₇Ni₃-CNT reveals an excellent ammonia synthesis performance, which has the highest Faraday efficiency (FE, 99.18%) at −0.8 V vs. reversible hydrogen electrode (RHE), along with an ammonia production rate of 20.90 mg·cm⁻²·h⁻¹. In addition, the highest ammonia production rate of Cu₇Ni₃-CNT can reach 23.21 mg·cm⁻²·h⁻¹, with a high FE (90.80%) at −1.0 V vs. RHE. At the same time, the electrocatalyst displays exceptional stability, which can operate steadily for 400 h at 300 mA·cm⁻². The high catalytic activity and excellent stability derive from catalyst structure and the synergistic effect between Cu₇Ni₃ alloy and encapsulating bamboo-like CNT. The incorporation of Ni enhances the intrinsic activity of Cu for NO₃RR. CNT endows the catalyst with a larger specific surface area, more exposed active sites to further improve the apparent activity, and higher stability. The internal cavity of CNT also contributes to the enrichment of nitrate. Furthermore, in-situ Raman spectroscopy and density functional theory (DFT) calculations reveal that Cu in the alloy can effectively adjust the adsorption energy of *NO₃ by Ni element and increase the activity of *H as the reduction driving force, thereby improving the intrinsic activity of NO₃RR.

In response to alleviate the escalating environmental pollution and energy scarcity, the development of a cost-effective, efficient and stable bifunctional oxygen reduction reaction/oxygen evolution reaction (ORR/OER) electrochemical catalyst for new energy conversion devices holds significant value. In this context, we present a two-step hydrothermal/annealing synthesis approach of CoFe alloy nanoparticles on nitrogen-doped ultra-thin carbon nanosheets as an excellent ORR/OER bifunctional catalyst. The hydrothermal process facilitates the intercalation of CoFe layered double hydroxide (CoFe LDH) onto the nitrogen-doped ultra-thin carbon layer, followed by an in-situ transformation into carbon-coated nano-alloy particles (Co₃Fe₇@NCNS) during high-temperature annealing. Co₃Fe₇@NCNS exhibits exceptional ORR activity (onset potential (E_onset) = 0.962 V, half-wave potential (E_1/2) = 0.869 V) and bifunctional electrocatalytic performance, accompanied by a low reversible overvoltage of 0.82 V. Combining X-ray absorption fine structure (XAFS) spectroscopy and density functional theory (DFT) calculations, we elucidate that the strong interactions between the synthesized Co₃Fe₇@NCNS alloy particles optimize the adsorption energy of oxygen intermediates, thereby playing a crucial role in enhancing catalytic activity. Furthermore, the Co₃Fe₇@NCNS-equipped Zn-air battery demonstrates a higher open-circuit voltage of 1.46 V and remarkable power density of 202.8 mW·cm⁻². It also exhibits excellent cycling stability, with a high specific capacity of 779.2 mA·h·g⁻¹, outperforming that of the Pt/C-RuO₂ counterpart.