The exploitation of the stable and earth-abundant electrocatalyst with high catalytic activity remains a significant challenge for hydrogen evolution reaction. Being different from complex ...nanostructuring, this work focuses on a simple and feasible way to improve hydrogen evolution reaction performance via manipulation of intrinsic physical properties of the material. Herein, we present an interesting semiconductor-metal transition in ultrathin troilite FeS nanosheets triggered by near infrared radiation at near room temperature for the first time. The photogenerated metal-phase FeS nanosheets demonstrate intrinsically high catalytic activity and fast carrier transfer for hydrogen evolution reaction, leading to an overpotential of 142 mV at 10 mA cm
and a lower Tafel slope of 36.9 mV per decade. Our findings provide new inspirations for the steering of electron transfer and designing new-type catalysts.
Photocatalytic hydrogen evolution from water has triggered an intensive search for metal-free semiconducting photocatalysts. However, traditional semiconducting materials suffer from limited hydrogen ...evolution efficiency owing to low intrinsic electron transfer, rapid recombination of photogenerated carriers, and lack of artificial microstructure. Herein, we report a metal-free half-metallic carbon nitride for highly efficient photocatalytic hydrogen evolution. The introduced half-metallic features not only effectively facilitate carrier transfer but also provide more active sites for hydrogen evolution reaction. The nanosheets incorporated into a micro grid mode resonance structure via in situ pyrolysis of ionic liquid, which show further enhanced photoelectronic coupling and entire solar energy exploitation, boosts the hydrogen evolution rate reach up to 1009 μmol g
h
. Our findings propose a strategy for micro-structural regulations of half-metallic carbon nitride material, and meanwhile the fundamentals provide inspirations for the steering of electron transfer and solar energy absorption in electrocatalysis, photoelectrocatalysis, and photovoltaic cells.
The future of sustainable fertilizers and carbon-free energy carrier demands innovative breakthroughs in the exploitation of efficient electrocatalysts for synthesizing ammonia (NH3) from nitrogen ...(N2) in mild conditions. Understanding and regulating the reaction intermediates that form on the catalyst surface through careful catalyst design could bypass certain limitations associated with ambiguous adsorbate evolution mechanism. Herein, we propose ternary intermetallic Re2MnS6 ultrathin nanosheets that include orderly hybridized Mn–Re dual-metal sites through strong Hubbard e-e interaction, demonstrating a promising selectivity toward reaction process from N2 to NH3. The ordered inclusion of Mn sites leads to a structural phase transition and appearance of nonbonding semimetal states, in which the rate-limiting activation energy barrier is significantly decreased through a conversion in reaction pathway. As a result, the performance of N2 reduction in Re2MnS6 is increased about 6.6 times compared to the single-metal ReS2.
Abstract
In this paper, the propagation properties of partially coherent radially polarized rotationally-symmetric power-exponent-phase vortex beams (RP-RSPEPVBs) in turbulent atmosphere were ...investigated. Based on the extended Huygens-Fresnel principle and unified theory of coherence and polarization, the theoretical propagation model was established. Then, the numerical simulations were carried out to reveal the evolution of intensity distribution, spectral degree of coherence (DOC) and spectral degree of polarization (DOP) in turbulent atmosphere. The results showed that although the partially coherent RP-RSPEPVBs diverged during the propagation, the spatial structure remains analogous, and the relatively larger waist widths gain smaller divergence. Moreover, the optical pattern can be evidently modulated by optical parameters, as the number of sidelobes can be changed with topological charge
l
, and the continuity of the light spot as well as the rotating speed around the optical axis can be influenced by power exponent
n
. Besides, the spectral DOC and DOP would decrease with larger propagation distance and refractive-index structure constant, but decrease less with a shorter coherence width. This work may be helpful in fields such as remote sensing and optical communication.
The ±1-order Kelly sidebands with dispersion-dependent spacing of mode-locking fiber lasers are investigated for frequency-tunable terahertz signal generation. The principle of dispersion dependence ...of Kelly sidebands is analyzed. A new method, which is a dispersion-management mechanism introduced into the fiber-laser cavity, is proposed to generate Kelly sidebands with widely tunable wavelength spacing. A spacing tuning range of up to 28.46 nm of the ±1-order Kelly sidebands is obtained in simulation. Using the data of the optical spectrum with dispersion-dependent Kelly sidebands, the frequency spectrum of generated terahertz signals is calculated. Consequently, the signal frequency can be changed from 0.09 to 2.27 THz.
•In this paper, a method for the generation of multiple rotationally-symmetric power-exponent-phase vortex beams (RPVBs) on a spatial arbitrary distribution was introduced and demonstrated, of which ...the flexibilities of user-defined spatial arbitrary distribution were illustrated by applying an appropriated computer-generated hologram (CGH) on a spatial light modulator (SLM).•The CGH was generated by superposing the interference pattern of a single RPVB, which derived from a phase mask of Laguerre-Gaussian (LG) beam and RPVB, and the phase shift calculated by the lenses and gratings (L&G) algorithm.•Compared with the results of a single RPVB, the properties of individual spatial arbitrary distribution RPVBs were still kept the same as the CGH generated by the L&G algorithm, which would only bring a phase shift and would not involve additional phase transformations.
In this paper, a method for generating multiple rotationally-symmetric power-exponent-phase vortex beams (RPVBs) on a spatial arbitrary distribution was demonstrated. The properties of a single RPVB were studied experimentally and theoretically with good agreement. Then, the flexibilities of user-defined spatial arbitrary distribution of multiple RPVBs were illustrated by applying an appropriated computer-generated hologram (CGH) on a spatial light modulator (SLM). This CGH was generated by superposing the interference pattern of a single RPVB, which derived from a phase mask of Laguerre-Gaussian (LG) beam and RPVB, and the phase shift calculated by the lenses and gratings (L&G) algorithm. As a result, the user-defined beam number, radial exponent (p), topological charge (TC), and power exponent (n) of the RPVBs can be controlled. Compared with the results of a single RPVB, the properties of individual spatial arbitrary distribution RPVBs were still kept the same as the CGH generated by the L&G algorithm, which would only bring a phase shift and would not involve additional phase transformations. The propagation properties of the multiple RPVBs were also studied. These results will extend the applications of RPVBs in optical trapping and may provide a new method to generate complex patterns like chiral structures.
The thermal blooming effect of power-exponent-phase vortex (PEPV) beam propagating in the atmosphere is investigated by employing the multiple phase screen method. The influences of propagation ...distance, topological charge, power exponent, wind speed, and absorption coefficient on thermal blooming effect are analyzed in detail. The results show that (1) the thermal blooming effect exhibits a significant perturbation on the intensity and phase distribution of PEPV beams, with its influence becoming more pronounced as the propagation distance increases; (2) when the power exponent is fixed at 4, comparing the thermal blooming effect of PEPV beams with different topological charges indicates that a PEPV beam with topological charges of 3 is the most sensitive to thermal blooming; (3) when the topological charge is fixed at 3, the thermal blooming effect decreases with the increase in power exponent; and (4) an increase in wind speed or a decrease in absorption coefficient can reduce the thermal blooming effect. The research results obtained in this article have guiding significance for the application of research into high-energy PEPV beams in the atmosphere.
In this paper, partially coherent radially polarized (RP) Laguerre-Gaussian (LG) rotationally symmetrical power-exponent phase vortex (RSPEPV) beams with the LG-correlated Schell-model (LGSM) were ...introduced. The statistical properties of the tightly focused beams, including intensity distribution, degrees of polarization and coherence, and Stokes vector, were studied based on vectorial Richards-Wolf diffraction integral theory. Moreover, when the distance between focal plane and the observation plane z = 0, the relationships between the tight-focusing properties of RP-LG-RSPEPV beams with LGSM and the order of LGSM p’, topological charges l, power exponent n, spatial correlation δ, and radial index p were investigated. The results show that by changing the order of LGSM, topological charge, power exponent, spatial correlation length, and radial index, the focal spot distribution of various shapes can be obtained. This work provides ideas for the application of partially coherent beams in particle capture and optical tweezers.
In this work, the second harmonic (SH) of higher-order Poincaré sphere (HOPS) beam was introduced and demonstrated with two orthogonal 5%MgO:PPLN crystals. Based on the quasi-phase-matching ...technique, the vectorial coupled wave equations were derived to simulate the SH of HOPS beams through the two crystals, including the cylindrical vector beams (CVBs), elliptically polarized CVBs (EPCVBs), and circularly polarized vortex beams. Then, the experimental setup was established to reveal that the SH of CVBs and EPCVBs present the four-lobed structure and still exhibit vector characteristics. Meanwhile, the circularly polarized vortex beams become the linearly polarized vortex beams with double phase topology, confirming the conservation of orbital angular momentum. Moreover, the maximum SH conversion efficiency of CVBs, EPCVBs, and circularly polarized vortex beams can reach 25.3%, 23.4%, and 29.4%, respectively, which may be instructive for promoting the SH generation of vector vortex beams with high efficiency.
In patients with previously treated advanced or metastatic non-small cell lung cancer (NSCLC), atezolizumab therapy improves survival with manageable safety. The open-label, single-arm phase III/IV ...TAIL study (NCT03285763) evaluated atezolizumab monotherapy in patients with previously treated NSCLC, including those with Eastern Cooperative Oncology Group performance status of 2, severe renal impairment, prior anti-programmed death 1 therapy, autoimmune disease, and age ≥75 years. Patients received atezolizumab intravenously (1200 mg) every 3 weeks. At data cut-off for final analysis, the median follow-up was 36.1 (range 0.0–42.3) months. Treatment-related (TR) serious adverse events (SAEs) and TR immune-related adverse events (irAEs) were the coprimary endpoints. Secondary endpoints included overall survival (OS), progression-free survival (PFS), overall response rate, and duration of response. Safety and efficacy in key patient subgroups were also assessed. TR SAEs and TR irAEs occurred in 8.0% and 9.4% of patients, respectively. No new safety signals were documented. In the overall population, median OS and PFS (95% CI) were 11.2 months (8.9 to 12.7) and 2.7 months (2.3 to 2.8), respectively. TAIL showed that atezolizumab has a similar risk-benefit profile in clinically diverse patients with previously treated NSCLC, which may guide treatment decisions for patients generally excluded from pivotal clinical trials.
PDF
