Yan Wang

The development of efficient and durable electrocatalysts for industrial-level water splitting remains a critical challenge. Here we report a CuO-MoS2/MoO3 precatalyst that undergoes electrochemical reconstruction under working conditions to yield two distinct active phases: Cu-MoS2 for the hydrogen evolution reaction (HER) at the cathode and an optimized CuO-MoS2/MoO3 for the oxygen evolution reaction (OER) at the anode. In 1.0 M KOH, the reconstructed electrodes deliver remarkably low overpotentials of 35 mV for HER and 124 mV for OER at 10 mA cm-2, along with outstanding long-term durability, sustaining 500 mA cm-2 for 100 h. Combined in situ Fourier-transform infrared spectroscopy and density functional theory calculations reveal that Cu species not only enhance charge transport but also tailor the electronic structure to optimize intermediate adsorption and reorganize interfacial water into a strongly hydrogen-bonded network, thereby accelerating water dissociation and proton transfer kinetics. When assembled into an anion-exchange-membrane water electrolyzer, the system delivers 1.0 A cm-2 at a low voltage of 1.77 V and 80 °C, with stable operation for 500 h, substantially surpassing noble-metal benchmarks. Our findings offer an efficient and durable catalyst system for sustainable hydrogen production, as well as fundamental insights into catalyst reconstruction and interfacial water regulation that inform the rational design of electrocatalytic materials.

With the rapid advancement and widespread adoption of millimeter-wave technology, developing high-performance microwave-absorbing materials has become critical for addressing electromagnetic interference and radiation pollution. To meet electromagnetic compatibility requirements in the 18−40 GHz frequency range, this study proposes a Nb5+-Mn2+ cosubstitution strategy and fabricates Ba(NbMn)xFe12-2xO19 absorbers via a sol-gel method. The results show that increasing the substitution ratio (X) modifies ion occupation, shifting the absorbers’ natural resonance frequency to the 21 GHz and 35 GHz atmospheric windows while broadening the microwave absorption bandwidth. Specifically, when X = 0.3, the absorber achieves an absorption peak of −43.37 dB in the K-band with an effective absorption bandwidth (EAB) of 6.46 GHz. When X = 0.2, it exhibits a superior absorption peak of −54.51 dB in the Ka-band, accompanied by an ultrabroad EAB of 12.87 GHz. The mechanism analysis reveals that Nb5+-Mn2+ cosubstitution constructs a synergistic magnetoelectric loss system: it enhances magnetic loss, triggers multidielectric polarization, and optimizes impedance matching which collectively enables excellent broadband microwave absorption through magnetoelectric synergy. This work provides a viable strategy for designing high-frequency microwave absorbers and highlights the significant potential of Nb5+-Mn2+ cosubstituted M-type barium ferrites in electromagnetic wave absorption applications.

Metasurfaces capable of realizing complex electromagnetic responses provide new design routes to the microwave absorption. The traditional optimization process of metasurface is time-consuming and computational resource-consuming. With the help of advanced deep learning methods, the design of the metasurface can be accelerated. In this paper, the trained residual neural network model is combined with an adjusted genetic algorithm to effectively reduce the optimization time of the metasurface pattern and structural parameters and achieve a broadband effective absorption. The trained residual neural network has good prediction ability, with 99.48% of the samples of the test set having a loss value below 5×10-5; the adjusted genetic algorithm is better able to search the potential space where the metasurface pattern is located. The optimal metasurface absorber covers the frequency range from 7.83 – 18.0 GHz (EAB 10.17 GHz) with a thickness of 3.97 mm. The combination of deep neural networks and optimization algorithm provide an effective way for the fast design of metasurface absorbers.

Rapid advances in communications technology and portable electronics necessitate lightweight, durable electromagnetic interference (EMI) shielding materials. Traditional metallic materials, despite their excellent shielding performance, are limited by high density, susceptibility to damage, and processing difficulties. To address this, we successfully fabricated a self-healing magnetic composite hydrogel with superior EMI shielding performance. This was achieved by incorporating Ni stellate microspheres (SMS) into a poly(vinyl alcohol) (PVA) hydrogel cross-linked with sodium tetraborate. A dense network of reversible hydrogen bonds and dynamic borate ester bonds within the PVA matrix imparted rapid ambient-temperature self-healing (92% efficiency) without external intervention. With 7 wt % Ni SMS loading, the composite hydrogel achieved a total shielding effectiveness (SE_T) of 61.5 dB in the X-band (8.2-12.4 GHz), retaining 56.3 dB posthealing. Remarkably, its SE_T exceeded 120 dB in the Ka-band (26.5-40 GHz). The Ni SMS synergistically enhanced shielding by optimizing conductive networks, interfacial polarization, and magnetic loss mechanisms. This work provides a new strategy for designing smart EMI shielding materials with significant potential for flexible electronics, aerospace, and wearable devices.

Size-controlled W-doped NiO nanocrystals contribute to the ultrahigh transmittance and minimal brownish tint.

The escalating demand for miniaturization and increased power in electronics presents substantial challenges in dealing with electromagnetic wave (EMW) radiation and heat accumulation within limited spaces. The design of multiple interfaces and components may enable effective EMW absorption that is harmoniously integrated with superior thermal conductivity features. In this work, sheet-on-sheet heterophase nanostructures were first constructed by assembling Ni(OH)₂ perpendicularly on CoAl-layered double hydroxides (CoAl-LDHs) using a hydrothermal method, followed by surface auto-polymerization of dopamine (PDA) to form [CoAl-LDHs/Ni(OH)₂]@PDA core–shell nanostructures, and finally [CoAlO/Ni]@C (CNC) was achieved with dielectric magnetic integration via pyrolysis. The CNC exhibits a high reflection loss (RL) of −61.8 dB with an effective absorption bandwidth (EAB) of 4.8 GHz at 1.81 mm, and the thermal conductivity is 0.572 W (m K)⁻¹. The significant microwave attenuation can be primarily attributed to the formation of numerous interfaces by heterostructures, which enhance the polarization relaxation loss. In addition, the three-dimensional (3D) channels composed of nanosheet arrays rely on multiple reflections and scattering to extend the propagation path of EMWs and increase their consumption. The superior thermal conductivity can be ascribed to the 3D graphitized carbon-coated metal particle framework. Furthermore, radar cross-section (RCS) simulations reveal that CNC could achieve desirable stealth in practice. This study introduces an alternative approach for designing a new generation of materials that simultaneously exhibit excellent EMW absorption and thermal conductivity.