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Designing an excellent acidic and alkaline general-purpose hydrogen evolution electrocatalyst plays an important role in promoting the development of the energy field. Here, a feasible strategy is reported to use the strongly coupled MoS2@sulfur and molybdenum co-doped g-C3N4 (MoS2@Mo-S-C3N4) heterostructure with transferable active centers for catalytic reactions in acidic and alkaline media. Research studies have shown that the unsaturated S site at the edge of MoS2 and the active N atom on the Mo-S-C3N4 substrate are, respectively, the active centers of acidic and alkaline hydrogen evolution reaction. Specifically, Mo-S-C3N4 is regarded as a synergistic catalyst for the active species MoS2 in acidic hydrogen evolution, while MoS2 acts as a co-catalyst when the alkaline active species are transferred to Mo-S-C3N4. The coordination of the electrons between the interfaces achieves a synergistic balance, which provides the optimal sites for the adsorption of the reactants. Such an electrocatalyst exhibits overpotentials of 193 and 290 mV at 10 mA cm–2 in 0.5 M H2SO4 and 1 M KOH, respectively, which was better than numerous previous reports. This research provides an outstanding avenue to realize multifunctional electrocatalysts.

Metamaterials are composed of periodic or quasi‐periodic subwavelength structures, having electric and/or magnetic responses. Metamaterials can arbitrarily tailor the refractive index by artificially tailoring the unit‐cell geometries and dimensions. Recent years, as the two dimensional equivalent of bulk metamaterials, metasurfaces have caused considerable attentions due to the lower profile and simpler to fabricate than bulk metamaterials. Metasurfaces can impart discontinuities on electromagnetic wavefronts and can achieve the arbitrary transmission phase of the whole period range. Metamaterials and metasurfaces have led to the realizations of novel electromagnetic properties and functionalities through tailoring subwavelength structures and integrating functional materials. In this letter, two planar lenses are respectively proposed to control the beam direction of the horn antenna by using a gradient refractive index (GRIN) metamaterial and a gradient phase (GRPH) metasurface. It is shown that the antenna beam direction can be steered by controlling the refractive index of the GRIN metamaterial or the transmission phase of the GRPH metasurface. The differences between the two planar lenses for controlling the antenna beam are illustrated.

Slow reaction kinetics, significant overpotential, and high cost remained significant barriers to electrocatalytic water splitting. To address such issues, “cicada-wing-like” nitrogen-doped porous carbon-anchored Ni and CeO2 nanoparticles (CeO2/Ni/NC) were developed and manufactured as a bifunctional catalyst utilizing a modified electrospinning process for overall water splitting. It is worth mentioning that the resulting CeO2/Ni/NC catalyst had excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalytic performance, as well as superior alkaline electrolyte durability. Compared with other nitrogen-doped carbon catalysts, in the OER, it revealed with a lower OER overpotential of 390 mV at 10 mA·cm–2 and a smaller value of the Tafel slope (123 mV·dec–1), while in the HER, it showed an overpotential of 320 mV at 10 mA·cm–2 and a Tafel slope of 150 mV·dec–1. The metallic Ni was the main center of excellent catalytic activity, and the abundant oxygen vacancies and outstanding oxidation/reduction capabilities in CeO2 promoted the overall water splitting. Moreover, the porous nanoarchitecture of matrix material well controlled the size of Ni and CeO2, providing a wealth of active sites, facilitating the electron/ion transfer. This work provided ideas for non-metal-doped carbon-supported catalyst particles, and the catalytic material obtained by the cheap and simple preparation method had an ultrathin microscopic appearance like cicada-wing-like and excellent bifunctional catalytic activity.

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