Designing high-efficiency and low-cost bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance to produce hydrogen by water electrolysis. Herein, a hierarchical FeCo₂S₄@CoFe layered double hydroxide (LDH) core–shell structure catalyst was successfully fabricated via a hydrothermal–sulfuration–electrodeposition three-step method. The unique structure can provide more abundant catalytically active sites for the electrochemical reaction. The resulting FeCo₂S₄@CoFe LDH electrode only requires overpotentials of 115 and 247 mV to reach a current density of 10 mA cm⁻² for the HER and OER in 1 M KOH electrolyte, respectively. The electrode also exhibits a low Tafel slope and excellent stability. Furthermore, the bifunctional catalyst for overall water splitting can exhibit a cell voltage of 1.6 V at 10 mA cm⁻², along with outstanding durability for 24 h testing. This work provides a new strategy to design effective bifunctional catalysts for overall water splitting.

An ion-selective layer based on self-assembled polystyrene opals is integrated with an alumina nanoporous membrane to form nanofluidic diodes.

The development of multifunctional electromagnetic wave absorbing materials capable of operating in complex environments has become critically important in the field of electromagnetic protection. However, achieving materials that combine high absorption efficiency with exceptional thermal stability remains a significant challenge. Hollow SiC/C fibers, benefiting from their lightweight hollow structure, low thermal conductivity, and high thermal stability, present a promising solution to the problem of high-temperature electromagnetic wave absorption. In this study, hollow SiC/C nanofibers were successfully synthesized via a combined hydrothermal and carbothermal reduction approach. The resulting hollow SiC/C nanofibers exhibit ultralight characteristics, high-temperature stability, good elasticity and fatigue resistance, exceptional electromagnetic wave absorption performance, including an effective absorption bandwidth of 7.0 GHz at a thickness of 2.4 mm and an optimal reflection loss of -63.5 dB at a thickness of 1.4 mm. Moreover, the material demonstrates remarkable high-temperature dielectric stability, with its complex permittivity remaining virtually unchanged at 600°C. The formulated strategy provides a feasible approach for designing SiC matrix composite with stable dielectric properties and efficient electromagnetic wave absorption.

Nanomaterials with unique structures and functions have been widely used in the fields of microelectronics, biology, medicine, and aerospace, etc. With advantages of high resolution and multi functions (e.g., milling, deposition, and implantation), focused ion beam (FIB) technology has been widely developed due to urgent demands for the 3D fabrication of nanomaterials in recent years. In this paper, FIB technology is illustrated in detail, including ion optical systems, operating modes, and combining equipment with other systems. Together with the in situ and real-time monitoring of scanning electron microscopy (SEM) imaging, a FIB-SEM synchronization system achieved 3D controllable fabrication from conductive to semiconductive and insulative nanomaterials. The controllable FIB-SEM processing of conductive nanomaterials with a high precision is studied, especially for the FIB-induced deposition (FIBID) 3D nano-patterning and nano-origami. As for semiconductive nanomaterials, the realization of high resolution and controllability is focused on nano-origami and 3D milling with a high aspect ratio. The parameters of FIB-SEM and its working modes are analyzed and optimized to achieve the high aspect ratio fabrication and 3D reconstruction of insulative nanomaterials. Furthermore, the current challenges and future outlooks are prospected for the 3D controllable processing of flexible insulative materials with high resolution.

We described an ionic diode based on polypyrrole-modified graphene oxide membrane, which was prepared by a spontaneous oxidation polymerization of pyrrole monomers.