The excellent electrocatalytic activity of metal-organic frameworks (MOFs) has shown great potential in applications, but has also posed outstanding challenges due to their poor conductivity and electrochemical stability. Here, we report a novel and promising self-supported oxygen electrocatalyst featuring bimetallic MOF nanosheets loaded on femtosecond-laser-constructed CoCrFeNi high-entropy alloy substrate (CCM/FHEA). This integrated design leverages synergistic advantages—including expansive specific surface area, rapid electrolyte exchange, and strong electronic interaction—to achieve exceptional oxygen evolution reaction (OER) activity and stability, with a small overpotentials of 231 mV to reach the current density of 10 mA·cm⁻² and a Tafel slope of 53.3 mV·dec⁻¹. Furthermore, this electrocatalytic system recorded excellent reaction stability over 300 h with a constant current density of 150 mA·cm⁻² at the potential of 1.56 V vs. RHE. Finite-element simulations demonstrate the intensified potential gradients and electric field intensity on the CCM/FHEA electrode surface, while density-functional theory calculations uncover the regulated electronic structure and reduced reaction energy barrier in post-formed CoCu-based oxyhydroxide analogue during OER. This work provides a feasible strategy for the rational design and construction of MOFs-based hierarchical self-supported electrocatalysts for efficient energy conversion technologies.

The controllable transfer of droplets on the surface of objects has a wide application prospect in the fields of microfluidic devices, fog collection and so on. The Leidenfrost effect can be utilized to significantly reduce motion resistance. However, the use of 3D structures limits the widespread application of self-propulsion based on Leidenfrost droplets in microelectromechanical system. To manipulate Leidenfrost droplets, it is necessary to create 2D or quasi-2D geometries. In this study, femtosecond laser is applied to fabricate a surface with periodic hydrophobicity gradient (SPHG), enabling directional self-propulsion of Leidenfrost droplets. Flow field analysis within the Leidenfrost droplets reveals that the vapor layer between the droplets and the hot surface can be modulated by the SPHG, resulting in directional propulsion of the inner gas. The viscous force between the gas and liquid then drives the droplet to move.

Understanding laser induced ultrafast processes with complex three-dimensional (3D) geometries and extreme property evolution offers a unique opportunity to explore novel physical phenomena and to overcome the manufacturing limitations. Ultrafast imaging offers exceptional spatiotemporal resolution and thus has been considered an effective tool. However, in conventional single-view imaging techniques, 3D information is projected on a two-dimensional plane, which leads to significant information loss that is detrimental to understanding the full ultrafast process. Here, we propose a quasi-3D imaging method to describe the ultrafast process and further analyze spatial asymmetries of laser induced plasma. Orthogonally polarized laser pulses are adopted to illuminate reflection-transmission views, and binarization techniques are employed to extract contours, forming the corresponding two-dimensional matrix. By rotating and multiplying the two-dimensional contour matrices obtained from the dual views, a quasi-3D image can be reconstructed. This successfully reveals dual-phase transition mechanisms and elucidates the diffraction phenomena occurring outside the plasma. Furthermore, the quasi-3D image confirms the spatial asymmetries of the picosecond plasma, which is difficult to achieve with two-dimensional images. Our findings demonstrate that quasi-3D imaging not only offers a more comprehensive understanding of plasma dynamics than previous imaging methods, but also has wide potential in revealing various complex ultrafast phenomena in related fields including strong-field physics, fluid dynamics, and cutting-edge manufacturing.

Femtosecond laser technology has attracted significant attention from the viewpoints of fundamental and application; especially femtosecond laser processing materials present the unique mechanism of laser-material interaction. Under the extreme nonequilibrium conditions imposed by femtosecond laser irradiation, many fundamental questions concerning the physical origin of the material removal process remain unanswered. In this review, cutting-edge ultrafast dynamic observation techniques for investigating the fundamental questions, including time-resolved pump-probe shadowgraphy, ultrafast continuous optical imaging, and four-dimensional ultrafast scanning electron microscopy, are comprehensively surveyed. Each technique is described in depth, beginning with its basic principle, followed by a description of its representative applications in laser-material interaction and its strengths and limitations. The consideration of temporal and spatial resolutions and panoramic measurement at different scales are two major challenges. Hence, the prospects for technical advancement in this field are discussed finally.