The fast development of terahertz technologies demands high-performance electromagnetic interference (EMI) shielding materials to create safe electromagnetic environments. Despite tremendous breakthroughs in achieving superb shielding efficiency (SE), conventional shielding materials have high reflectivity and cannot be re-edited or recycled once formed, resulting in detrimental secondary electromagnetic pollution and poor adaptability. Herein, a hydrogel-type shielding material incorporating MXene and poly(acrylic acid) is fabricated through a biomineralization-inspired assembly route. The composite hydrogel exhibits excellent stretchability and recyclability, favorable shape adaptability and adhesiveness, and fast self-healing capability, demonstrating great application flexibility and reliability. More interestingly, the shielding performance of the hydrogel shows absorption-dominated feature due to the combination of the porous structure, moderate conductivity, and internal water-rich environment. High EMI SE of 45.3 dB and broad effective absorption bandwidth (0.2−2.0 THz) with excellent refection loss of 23.2 dB can be simultaneously achieved in an extremely thin hydrogel (0.13 mm). Furthermore, such hydrogel demonstrates sensitive deformation responses and can be used as an on-skin sensor. This work provides not only an alternative strategy for designing next-generation EMI shielding material but also a highly efficient and convenient method for fabricating MXene composite on macroscopic scales.

Mesoporous SiO2-modified nanocrystalline TiO2 photocatalysts have been prepared by sol-hydrothermal processes, followed by post-treatment with appropriate amount of surfactant F127-modified silica sol. The resulting photocatalysts were also characterized by X-ray diffraction, Raman spectroscopy, Brunauer−Emmett−Teller spectroscopy, N2 adsorption−desorption, transmission electron microscopy, FT-IR, X-ray photoelectron spectroscopy, UV−vis diffuse reflectance spectroscopy, steady state surface photovoltage (SS-SPV), and transient state surface photovoltage (TS-SPV) techniques. The photocatalytic activities of the samples were evaluated by degrading rhodamine B solution under simulated solar illumination. The results show that the surface modification with mesoporous SiO2 greatly enhances the thermal stability of the nanocrystalline anatase TiO2, even still being with a main anatase phase after calcination at 900 °C, and the more is the amount of SiO2 used, the more obvious is the ehancement in the thermal stability. This enhancement is attributed to the effective inhibition of the direct contacts and the diffusions among anatase nanocrystals as well as to the retardation of the crystallite growth. Interestingly, the proper amount of mesoporous SiO2-modified nanocrystalline TiO2 samples by thermal treatment at high temperature can exhibit much higher photocatalytic activity than the commercial-available P25 TiO2, which is explained mainly by the high photoinduced charge carrier separation rate resulting from the high anatase crystallinity based on the analyses of SS-SPV and TS-SPV responses and the large surface area related to the small nanocrystallite size and mesoporous SiO2 as well as still possessing a certain amount of surface hydroxyl group.

Developing cost‐effective and high‐performance catalysts for oxygen evolution reaction (OER) is essential to improve the efficiency of electrochemical conversion devices. Unfortunately, current studies greatly depend on empirical exploration and ignore the inherent relationship between electronic structure and catalytic activity, which impedes the rational design of high‐efficiency OER catalysts. Herein, a series of bimetallic Ni‐based metal‐organic frameworks (Ni‐M‐MOFs, M = Fe, Co, Cu, Mn, and Zn) with well‐defined morphology and active sites are selected as the ideal platform to explore the electronic‐structure/catalytic‐activity relationship. By integrating density‐functional theory calculations and experimental measurements, a volcano‐shaped relationship between electronic properties (d‐band center and eg filling) and OER activity is demonstrated, in which the NiFe‐MOF with the optimized energy level and electronic structure situated closer to the volcano summit. It delivers ultra‐low overpotentials of 215 and 297 mV for 10 and 500 mA cm−2, respectively. The identified electronic‐structure/catalytic activity relationship is found to be universal for other Ni‐based MOF catalysts (e.g., Ni‐M‐BDC‐NH2, Ni‐M‐BTC, Ni‐M‐NDC, Ni‐M‐DOBDC, and Ni‐M‐PYDC). This work widens the applicability of d band center and eg filling descriptors to activity prediction of MOF‐based electrocatalysts, providing an insightful perspective to design highly efficient OER catalysts.

The shuttle effect of lithium polysulfides (LiPS) and potential safety hazard caused by the burning of flammable organic electrolytes, sulfur cathode, and lithium anode seriously limit the practical application of lithium–sulfur (Li–S) batteries. Here, a flame‐retardant polyphosphazene (PPZ) covalently modified holey graphene/carbonized cellulose paper is reported as a multifunctional interlayer in Li–S batteries. During the discharge/charge process, once the LiPS are generated, the as‐obtained flame‐retardant interlayer traps them immediately through the nucleophilic substitution reaction between PPZ and LiPS, effectively inhibiting the shuttling effect of LiPS to enhance the cycle stability of Li–S batteries. Meanwhile, this strong chemical interaction increases the diffusion coefficient for lithium ions, accelerating the lithiation reaction with complete inversion. Moreover, the as‐obtained interlayer can be used as a fresh 3D current collector to establish a flame‐retardant “vice‐electrode,” which can trap dissolved sulfur and absorb a large amount of electrolyte, prominently bringing down the flammability of the sulfur cathode and electrolyte to improve the safety of Li–S batteries. This work provides a viable strategy for using PPZ‐based materials as strong chemical scavengers for LiPS and a flame‐retardant interlayer toward next‐generation Li–S batteries with enhanced safety and electrochemical performance.

It is still a big challenge to develop active, stable, and easy-to-make bifunctional non-noble electrocatalysts for upshifting overall urea-assisted water splitting toward practical environmental applications at large current densities with lower cell voltages. In response, here we report a competitive bifunctional electrocatalyst that can catalyze both the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) by fabricating the in situ grown Ni phosphate (shell)-anchored Ni12P5 nanorod (core) arrays on the 3D Ni foam skeleton (named as Ni12P5/Ni-Pi/NF). Benefiting from the unique hierarchical core–shell nanorod architecture with abundant exposed active sites and improved electron and mass transfer efficiency, such elaborate binder-free arrays could act as a robust 3D UOR anode and can achieve 900 mA cm–2 only at potentials of 1.378 V in 1.0 M KOH with 0.5 M urea. Additionally, this electrode also shows remarkable cathodic HER catalytic activities. Moreover, when constructing an alkaline electrolyzer using the bifunctional electrodes, the integrated system is capable of delivering the current density of 500 mA cm–2 stably for over 6 h at a cell voltage as low as 1.662 V, which is 287 mV less than that for pure water splitting. As such, our result may become a significant step in developing an industrial electrolyzer for meaningful massive electrocatalytic hydrogen (H2) production by urea-assisted water splitting.