Microcosmic 3D hierarchical structural design has proved to be an effective strategy to obtain high-performance microwave absorbers, although the treatments to low-dimensional cells in monolithic framework are usually based on semiempirical rules. In this work, a hierarchical carbon fiber (CF)@MXene@MoS 2 (CMM) core-sheath synergistic structure with tunable and efficient microwave absorption (MA) properties is fabricated by introducing self-assembled Ti 3 C 2 T x MXene on the surface of CF and subsequent anchoring of MoS 2. By the synergistic effects from the MXene sheath increasing the conductive loss and MoS 2 at the outermost layer improving the impedance matching, the MA performance of CMM can be effectively regulated and optimized: the optimal reflection loss is −61.51 dB with a thickness of 3.5 mm and the maximum effective absorption bandwidth covers the whole Ku-band with 7.6 GHz at 2.1 mm. Meanwhile, the whole X-band absorption can also be achieved with specific MoS 2 loading at an optimized thickness.

NaNbO 3 rods modified by In 2 O 3 nanoparticles (In 2 O 3 /NaNbO 3 ) were successfully synthesized by an improved coprecipitation method, and they were found to be advantageous for photocatalytic H 2 evolution under visible light irradiation and pure water splitting under ultraviolet light irradiation. The composites were characterized by X-ray diffraction, UV-vis diffuse reflectance spectrometry, Brunauer-Emmett-Teller measurement, scanning electron microscopy, energy-dispersive spectrometry, and transmission electron microscopy. With use of the electrochemical and valence band X-ray photoelectron spectroscopy analysis, the improvement of the photocatalytic activity was attributed to the promoted transportation of photoexcited holes in the composite.

Liquid metal forms a thin layer of oxide skin via exposure to oxygen and this layer could be exfoliated by mechanical delamination or gas-injection/solvent-dispersion. Although the room-temperature fabrication of two-dimensional (2D) oxide through gas-injection and water-dispersion has been successfully demonstrated, a synthetic protocol in nonaqueous solvent at elevated temperature still remains as a challenge. Herein we report the mass-production of amorphous 2D SnO x nanoflakes with Bi decoration from liquid Sn–Bi alloy and selected nonaqueous solvents. The functional groups of the solvents play a key role in determining the final morphology of the product and the hydroxyl-rich solvents exhibit the best control toward 2D SnO x . The different solvent-oxide interaction that facilitates this phase-transfer process is further discussed on the basis of DFT calculation. Finally, the as-obtained 2D SnO x is evaluated in electrocatalytic CO2 reduction with high faradaic efficiency (>90%) of formic acid and stable performance over 10 h.

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The effects of Sr substitution for Ba on photocatalytic water splitting activity of BaSnO3 were investigated experimentally and theoretically. The chemical incorporation of Sr into BaSnO3 induced a great enhancement for H2 production. Density function theory calculations of Ba1−xSrxSnO3 (x=0, 0.5, and 1.0) reveal that the bottom of the conduction band is gradually pushed up and the contribution of the Sr 5s orbitals to the bottom of the conduction band gradually becomes dominant with the increase of Sr concentration from x=0 to x=1.0. The participation of the normally inert Sr cation in the electronic structure of the SnO32− framework not only enhances the reduction ability of photoinduced electrons but also provides favorable opportunities for charge carrier transport, thus enhancing the photocatalytic activity of BaSnO3.

Oxygen evolution electrode is a crucial component of efficient photovoltaic‐water electrolysis systems. Previous work focuses mainly on the effect of electronic structure modulation on the oxygen evolution reaction (OER) performance of 3d‐transition‐metal‐based electrocatalyst. However, high‐atomic‐number W‐based compound with complex electronic structure for versatile modulation is seldom explored because of its instability in OER‐favorable alkaline solution. Here, codoping induced electronic structure modulation generates a beneficial effect of transforming the alkaline‐labile WO 2.72 (WO) in to efficient alkaline‐solution‐stable Co and Fe codoped WO 2.72 (Co&Fe‐WO) with porous urchin‐like structure. The codoping lowers the chemical valence of W to ensure the durability of W‐based catalyst, improves the electron‐withdrawing capability of W and O to stabilize the Co and Fe in OER‐favorable high valence state, and enriches the surface hydroxyls, which act as reactive sites. The Co&Fe‐WO shows ultralow overpotential (226 mV, J = 10 mA cm −2 ), low Tafel slope (33.7 mV dec −1 ), and good conductivity. This catalyst is finally applied to a photovoltaic‐water splitting system to stably produce hydrogen for 50 h at a high solar‐to‐hydrogen efficiency of 16.9%. This work highlights the impressive effect of electronic structure modulation on W‐based catalyst, and may inspire the modification of potential but unstable catalyst for solar energy conversion.

Left-handed metamaterials (LHMs) have recently been the focus of both scientific and engineering communities. [1,2] Simultaneously possessing negative dielectric permittivity e and magnetic permeability m, LHMs exhibit unique electromagnetic properties compared with normal, right-handed materials while still obeying Maxwell's equation and not violating known physical laws.[3] Although obtaining the e < 0 response was relatively easy, the realization of m < 0 response beyond MHz has been a challenge, owing to the absence of naturally occurring magnetic materials. In the late 1990s, Pendry theoretically proposed that LHMs can be realized in a composite materials form consisting of metallic wires and split-ring resonators (SRRs) components. [4,5] It was shown that a grid of thin conducting wires can produce a negative permittivity near its plasmonic frequency, and that an array of SRRs can produce a negative permeability in the vicinity of a certain magnetic resonance frequency v m . Because the electric resonance frequency of metallic wires and magnetic resonance frequency of SRRs are mainly dependant on their structural parameters, left-handed behavior in a given frequency can be realized if the electric and magnetic resonance frequency drop into the same region through adjusting the structural parameters of the metallic wires and SRRs, respectively. Since the first realization and verification of an artificial LHM at microwave frequencies in 2000, [6] there have been numerous studies on various aspects of LHMs, seeking their inner physics and pursuing possible applications. At the same time, much effort has been put into the fabrication and investigation of LHMs at IR and visible light frequencies.

In this study, a highly sensitive and self‐driven near‐infrared (NIR) light photodetector based on PdSe2/pyramid Si heterojunction arrays, which are fabricated through simple selenization of predeposited Pd nanofilm on black Si, is demonstrated. The as‐fabricated hybrid device exhibits excellent photoresponse performance in terms of a large on/off ratio of 1.6 × 105, a responsivity of 456 mA W−1, and a high specific detectivity of up to 9.97 × 1013 Jones under 980 nm illumination at zero bias. Such a relatively high sensitivity can be ascribed to the light trapping effect of the pyramid microstructure, which is confirmed by numerical modeling based on finite‐difference time domain. On the other hand, thanks to the broad optical absorption properties of PdSe2, the as‐fabricated device also exhibits obvious sensitivity to other NIR illuminations with wavelengths of 1300, 1550, and 1650 nm, which is beyond the photoresponse range of Si‐based devices. It is also found that the PdSe2/pyramid Si heterojunction device can also function as an NIR light sensor, which can readily record both “tree” and “house” images produced by 980 and 1300 nm illumination, respectively.