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Substituting slow oxygen evolution reaction (OER) with thermodynamically favorable urea oxidation reaction (UOR) is considered as one of the feasible strategies for achieving energy-saving hydrogen production. Herein, a uniform layer of NiMoO4 nanorods was grown on nickel foam by a hydrothermal method. Then, a series of Ni-MoOx/NF-X nanorod catalysts comprising Ni/NiO and MoOx (MoO2/MoO3) were prepared through regulating annealing atmosphere and reduction temperature. The optimized Ni-MoOx/NF-3 with a large accessible specific area can act as a bifunctional catalyst for electrocatalytic anodic UOR and cathodic hydrogen evolution reaction (HER). At a current density of 100 mA cm−2, the introduction of urea can significantly reduce the overpotential of Ni-MoOx/NF-3 by 210 mV compared to OER. In addition, Ni-MoOx/NF-3 has a higher intrinsic activity than other catalysts. It only requires −0.21 and 1.38 V to reach 100 mA cm−2 in HER and UOR, respectively. Such an excellent performance can be attributed to the synergistic function between Ni and MoOx. The presence of metallic Ni and reduced MoOx in pairs is beneficial for improving the electrical conductivity and modulating the electronic structure, resulting in enhancing the electrocatalytic performance. When assembling Ni-MoOx/NF-3 into an overall urea–water splitting system, it can achieve energy-saving hydrogen production and effective removal of urea-rich wastewater. [ABSTRACT FROM AUTHOR]

The investigation on the temporal dynamics of graphene-wrapped core–shell nanoparticles under the illumination of a Gaussian impulse have been carried out. By altering the graphene layers and the aspect ratio of the core–shell structure, we can adjust the resonant modes into typical cases in regime of terahertz. Accordingly, different scenarios for the temporal evolution are detected, which include two kinds of ultrafast oscillation with exponential decay tendency, pure exponential decay, and Gaussian shape, when the pulse duration of the incident pulse is much shorter than, similar to, and much longer than the localized surface plasmon lifetime. To one's interest, when the coupling between two resonant modes exists, one predicts the long-periodic oscillation, whose period is just the difference between the frequencies of the resonant modes. Hence, the intrinsic properties of the ultrafast oscillation can be hardly influenced by the input signals. Further quantitative calculation demonstrate that the periods of the ultrafast oscillations can be tuned by different physical mechanisms, which are, respectively, based on the self-interacting correction of a single resonance and the strong coupling between the resonant modes in frequency domain. Our results may be applicable in the fields of optical sensors, optical information processing, and other nanophotonic devices. [ABSTRACT FROM AUTHOR]

In this paper, a promising method for growing large-sized and high-quality Mg2SiO4 single crystals was explored, and a transparent Mg2SiO4 single crystal, 30 mm in diameter and 80 mm in length, was successfully grown by the Czochralski method. The morphology of dislocation was studied by chemical etching and explained by surface energy based on the density functional theory (DFT) method. And the anisotropy of its thermodynamic and optical properties was studied. The experimental results showed a maximum Mohs hardness of 6.84 and the highest thermal conductivity of 11.73 W m−1 K−1, indicating that Mg2SiO4 has higher hardness and better thermal properties. Furthermore, the refractive index curves along the three principal axes in the range of 200–1700 nm and transmittance curves in the range of 200–2500 nm were obtained. The maximum phonon energy of the Mg2SiO4 crystal was determined. Finally, the band structure and density of states (DOS) were calculated based on the DFT method. These results provide an important reference for the application of Mg2SiO4 as a near-infrared tunable laser crystal host. [ABSTRACT FROM AUTHOR]

Non-contact optical temperature sensing technology, particularly based on the fluorescence intensity ratio principle of the thermally coupled energy levels of Er3+, has emerged as a prominent area of research for upconversion luminescent materials in temperature detection. To advance the development of novel upconversion luminescent materials for optical temperature sensing, an upconversion phosphor, GdScO3:Yb3+/Er3+, with low phonon energy, was synthesized using a high-temperature solid-state method. The crystal structure, maximum phonon energy, and elemental distribution of the sample were characterized through powder X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy. The upconversion emission spectrum of the sample under 980 nm excitation and the excited state absorption process under different power density excitations were thoroughly investigated. The findings demonstrate the commendable performance of the GdScO3:Yb3+/Er3+ phosphor, which exhibits a suitable thermally coupled energy levels energy difference (ΔE) of 630 cm− 1, an exceptional relative sensitivity of 1.007% K− 1 at 300 K, and a minimal temperature resolution of 0.49 K at 300 K. The remarkable consistency and robust thermal stability of the GdScO3:Yb3+/Er3+ phosphors underscore their potential in highly sensitive optical thermometry applications. [ABSTRACT FROM AUTHOR]

Background: Sports records hold valuable insights into human physiological limits. However, presently, there is a lack of integration and evolutionary patterns in the recorded information across various sports. Methods: We selected sports records from 1992 to 2018, covering 24 events in men's track, field, and swimming. The Gembris prediction model calculated performance randomness, and Pearson correlation analysis assessed network relevance between projects. Quantitative study of model parameters revealed the impact of various world records' change range, predicted value, and network correlation on evolutionary patterns. Results: 1) The evolution range indicates that swimming events generally have a larger annual world record variation than track and field events; 2) Gembris's predictions show that sprint, marathon, and swimming records outperform their predicted values annually; 3) Network relevance analysis reveals highly significant correlations between all swimming events and sprints, as well as significant correlations between marathon and all swimming events. Conclusion: Sports record evolution is closely linked not only to specific sports technology but also to energy expenditure. Strengthening basic physical training is recommended to enhance sports performance. [ABSTRACT FROM AUTHOR]