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Electrocatalytic nitrogen reduction reaction (NRR) has attracted much attention as a sustainable ammonia production technology, but it needs further exploration due to its slow kinetics and the existence of competitive side reactions. In this research, xAu/MIL‐101(Fe) catalysts were obtained by loading gold nanoparticles (Au NPs) onto MIL‐101(Fe) using a one‐step reduction strategy. Herein, MIL‐101(Fe), with high specific surface area and strong N2 adsorption capacity, is used as a support to disperse Au NPs to increase the electrochemical active surface area. Au NPs, with a high NRR activity, is introduced as the active site to promote charge transfer and intermediate formation rates. More importantly, the strong interaction between Au NPs and MIL‐101(Fe) enhances the electron transfer between Au NPs and MIL‐101(Fe), thereby enhancing the activation of N2 and achieving efficient NRR. Among the prepared catalysts, 15 %Au/MIL‐101(Fe) has the highest NH3 yield of 46.37 μg h−1 mg−1cat and a Faraday efficiency of 39.38 % at −0.4 V (vs. RHE). In‐situ FTIR reveals that the NRR mechanism of 15 %Au/MIL‐101(Fe) follows the binding alternating pathway and also indicates that the interaction between Au NPs and MIL‐101(Fe) strengthens the activation of the N≡N bond in the rate‐limiting process, thereby accelerating the NRR process. [ABSTRACT FROM AUTHOR]

Enrofloxacin (ENR) is a commonly used veterinary antibiotic and poses a health risk when present as residues in food. This study describes a dual-mode immunochromatographic test strip (DITS) biosensor for the detection of ENR residues in food. Magnetic graphene oxide nanoparticles (MGO-NPs) are two-dimensional magnetic nanomaterials with a large specific surface area and fine biocompatibility, which can better provide more adsorption points for biological antibodies. Gold nanoparticles (AuNPs) can stimulate the localized surface plasmon resonance effect under laser irradiation, which will increase the temperature to achieve photothermal conversion. The photothermal conversion efficiency of MGO-NPs can be effectively enhanced by combining AuNPs with MGO-NPs to form MGO@Au nanocomposites (MGO@Au-NCs). Then, MGO@Au-NCs were combined with an ENR monoclonal antibody to form the MGO@Au@Ab probe, and the MGO@Au@Ab-DITS biosensor was developed. The biosensor was employed to assess ENR samples spanning concentrations from 0 to 1000 μg/mL. Sample solutions containing ENR were mixed with the MGO@Au@Ab solution, deposited on the test strip's sample pad, and analyzed using both colorimetric and photothermal methods employing an 808 nm infrared laser in a photothermal infrared imaging instrument. The results show that the sensitivity of the photothermal mode sensor is 0.0159°C whereas, the standard deviation (SD) and limit of detection (LOD) is 0.058 and 10.89 μg/mL, respectively with quantification limit (LOQ) of 36.31 μg/mL. In colorimetric mode, the sensitivity of the developed sensor is 5.222 au, with SD, LOD and LOQ of 40.13, 23.05 μg/mL, and76.85 μg/mL, respectively. This innovative MGO@Au@Ab-DITS system has been effectively applied to detect ENR residues in food samples such as juice and milk, laying the groundwork for the detection of other drug residues in food. [ABSTRACT FROM AUTHOR]

An effective approach to manipulate terahertz (THz) waves involves the utilization of a device structure. In this particular investigation, we have successfully fabricated a SnS2 nanofilm device using femtosecond laser direct ablation. The passive and active polarization‐sensitive characteristics of the SnS2 nanofilm device were examined within the THz frequency range, employing different line spaces of 500, 600, and 700 μm. The combination of the device effect and SnS2 absorption led to an enhanced passive polarization modulation. Moreover, when an external electric field was applied to the SnS2 nanofilm device along the device line, persistent switching and linear modulation of THz wave transmission were observed. These findings indicate that the integration of material properties and device structure in this SnS2 device renders it highly suitable for applications in ultrafast THz switches, filters, and modulation devices. [ABSTRACT FROM AUTHOR]

Lanthanum hexaaluminate (LHA) supported NiO catalysts (xNi/LHA) with varied mass loading of Ni (x = 15, 20, 25, 30 wt%) were prepared by impregnating NiO nanoparticles (NPs) on LHA support that synthesized through urea combustion method. The catalysts were characterized by high-resolution transmission electron microscope (HRTEM), temperature programmed reduction (TPR), temperature programmed desorption (TPD), etc. The results showed that NiO NPs were dispersed densely on the LHA surface. The 25Ni/LHA catalyst provided the optimal ammonia conversion of 85.75% with a space velocity of 30,000 ml gcat−1 h−1 at 600 °C, corresponding to the hydrogen production rate of 28.73 mmol H2 gcat−1 min−1. The strong alkalinity of LHA could modify the interaction between the active sites and the nitrogen of ammonia, which was conducive to the ammonia decomposition reaction. The high performance of the catalyst represented a feasible approach towards the application of ammonia as hydrogen carrier to produce hydrogen. [ABSTRACT FROM AUTHOR]

Ni nanocatalysts based on high surface area carborundum for the decomposition of ammonia to COx-free hydrogen are synthesized using a wet impregnation approach. The catalysts were characterized using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and H2-temperature-programmed reduction (TPR) methods. The Ni/SiC catalyst was found to be extremely active for the decomposition reaction when their activities were assessed in a fixed-bed reactor. Ni content and calcination temperature affect the crystallite size, dispersion, and reducibility of Ni species, thereby impacting the catalytic properties of catalysts. The 30Ni/SiC catalyst demonstrates the highest catalytic activity and long-term stability. At a high space velocity of 30 000 mL gcat–1 h–1, the 30Ni/SiC-700 catalyst converts ammonia by 79.6% at 550 °C, demonstrating that Ni/SiC is an effective ammonia decomposition catalyst. The present study provides a promising avenue for the development of cost-effective and high-performance catalysts for hydrogen production via NH3 decomposition. [ABSTRACT FROM AUTHOR]

Optical fiber sensors based on tapered optical fiber (TOF) structure have attracted a considerable amount of attention from researchers due to the advantages of simple fabrication, high stability, and diverse structures, and have great potential for applications in many fields such as physics, chemistry, and biology. Compared with conventional optical fibers, TOF with their unique structural characteristics significantly improves the sensitivity and response speed of fiber-optic sensors and broadens the application range. This review presents an overview of the latest research status and characteristics of fiber-optic sensors and TOF sensors. Then, the working principle of TOF sensors, fabrication schemes of TOF structures, novel TOF structures in recent years, and the growing emerging application areas are described. Finally, the development trends and challenges of TOF sensors are prospected. The objective of this review is to convey novel perspectives and strategies for the performance optimization and design of TOF sensors based on fiber-optic sensing technologies. [ABSTRACT FROM AUTHOR]

This paper presents the development of taper-in-taper fiber (TITF)–optical fiber-based sensors for chemical and biological detection. TITF structure is a fiber structure formed by fabricating a taper again on the taper region of the traditional taper fiber. The experimental results show that the TITF structure has a lower transmitted intensity than the common taper fiber structure. It is demonstrated that the structure of TITF is more conducive to evanescent waves, thereby making it more sensitive to changes in the refractive index (RI) of the external environment. To confirm this, measurements of ethanol solutions with different water contents are taken using the TITF structure to showcase the chemical sensing, thus verifying its sensitivity to RI changes in the external environment. The sensor can measure ethanol solutions from 0 to 100% with a sensitivity of 4.06 a.u./%. Thereafter, the TITF sensor is modified with ZnO-NPs to enhance its sensitivity for biological sensing (creatinine detection). The transmitted intensity of different concentrations of creatinine solution (0–2000 μM) is measured using the proposed sensor. The sensor showed good linearity and a high sensitivity of 0.11 a.u./μM for creatinine solution. Therefore, it is demonstrated that the TITF sensor with ZnO-NPs can be used for effective biological sensing. [ABSTRACT FROM AUTHOR]

Niobium carbide (Nb2CTx), a type of MXene with high optical transparency, large specific surface area, and good electrical conductivity, is expected to perform as an excellent medium in the field of optical fiber biosensing. Here, we fabricated double S-tapered fiber sensors functionalized with gold nanoparticles/graphene oxide/tyrosinase (AuNPs/GO/tyrosinase) and AuNPs/Nb2CTx/tyrosinase, respectively. The double S-tapered structure can provide more evanescent wave leakage and enhance light–matter interaction. By implementing transmittance experiment, the sensitivity of the two probes were tested to be 17 and 34 pm/μM over 0–300 μM tyramine concentrations. The comparative results demonstrate that Nb2CTx-enhanced localized surface plasmon resonance (LSPR) sensor has more excellent performance due to the existence of surface functional groups and large specific surface area of Nb2CTx. Our work provides a research platform for improving the sensitivity of LSPR sensors. [ABSTRACT FROM AUTHOR]

This article discusses optically active nanomaterials and their optical biosensing applications. In addition to enhancing their sensitivity, these nanomaterials also increase their biocompatibility. For this reason, nanomaterials, particularly those based on their chemical compositions, such as carbon-based nanomaterials, inorganic-based nanomaterials, organic-based nanomaterials, and composite-based nanomaterials for biosensing applications are investigated thoroughly. These nanomaterials are used extensively in the field of fiber optic biosensing to improve response time, detection limit, and nature of specificity. Consequently, this article describes contemporary and application-based research that will be of great use to researchers in the nanomaterial-based optical sensing field. The difficulties encountered during the synthesis, characterization, and application of nanomaterials are also enumerated, and their future prospects are outlined for the reader's benefit. [ABSTRACT FROM AUTHOR]

A novel experimental setup for the generation of arbitrary vector beams is proposed. The system major includes two reflective liquid crystal spatial light modulators (RLC-SLM) and a polarizing beam splitting prism. Moreover, this method is not limited by the wavelength of light wave and the pixel size of SLM. Theoretical analysis shows that when Gaussian beam or a plane beam is illuminated on a computer-generated hologram (CGH) specially designed in this work, the complex amplitudes of the vector field's two orthogonal polarization components may be changed by modifying the encoding parameters, resulting in a vector beam with arbitrary complex amplitude and polarization in the output field. The experimental results also show that the two independent coding channels of the device have good polarization-selective imaging ability, which greatly improves the flexibility of generating arbitrary vector beams. [ABSTRACT FROM AUTHOR]

Glucose, an essential nutrient to the metabolism of organisms, is closely related to human health. Here, a novel serial quadruple tapered structure-based localized surface plasmon resonance (LSPR) sensor is employed to achieve accurate detection of glucose level in the human body. Gold nanoparticles (AuNPs) are immobilized on the serial quadruple taper fiber (SQTF) to induce LSPR. Furthermore, graphene oxide (GO) and multi-wall carbon nanotubes (MWCNTs) are used to increase the binding sites of enzymes to improve the sensing performance of probe. In our work, the SQTF probe surface is functionalized with glucose oxidase (GOx) enzyme to enhance selectivity. The sensitivity and limit of detection (LOD) of functionalized probe structure are 1.04 nm/mM and 0.24 mM over a linear range of 0 mM to10 mM, respectively. In addition, the reusability, reproducibility, stability and selectivity of SQTF probe are assessed to demonstrate the potential in measuring glucose content in the human body. [ABSTRACT FROM AUTHOR]

Summary: To reduce the overpotential of electrocatalytic oxygen evolution reaction (OER) for high‐efficiency water splitting, a series of 2 to 5 nm ultrafine spinel Co3O4 nanoparticles (NPs) with varied amount of lattice‐doped Te (XTe‐Co3O4, X represents the nominal molar ratio Te/Co of 0, 2, 4, 6, 8%) as catalysts were prepared through a simple hydrothermal synthesis method. The 6%Te‐Co3O4 catalyst was optimized to obtain the overpotential as low as 313 mV at 10 mA cm−2, a small Tafel slope of 75 mV dec−1 in 1 M KOH for OER, outperforming this series and many reported Co3O4‐based catalysts. Te doping introduced lattice distortion and resulted in smaller size of Te‐Co3O4 NPs with enlarged surface area for more accessible active sites. Oxygen vacancies were created to modify the electronic structure, improve the active sites density, and decrease the kinetic energy barriers of XTe‐Co3O4. The electronic conductivity of 6%Te‐Co3O4 was improved to accelerate the charge transfer efficiency. All these effects contributed to promoting the reaction kinetics and minimizing the OER overpotentials for high‐performance electrocatalysis. [ABSTRACT FROM AUTHOR]

Terahertz parametric oscillator (TPO) with a rhombic ring-cavity is demonstrated. The oscillating cavity is composed of three mirrors and the terahertz emitting-surface. Terahertz frequency can be tuned from 0.9 THz to 2.9 THz just by shifting the position of a cavity mirror. Under a certain round-trip optical length of the Stokes beam, the pump beam size can be larger in the rhombic ring-cavity TPO than that in the conventional resonant-cavity TPO. The maximum terahertz pulse energy in the rhombic ring-cavity TPO is 3.21 ÎĽ J, which is about 3 times higher than that in the conventional resonant-cavity TPO. [ABSTRACT FROM AUTHOR]

Summary Water splitting driven by renewable energy represents a sustainable way to store clean energy. However, its efficiency is limited by the kinetically sluggish oxygen evolution reaction (OER), calling for highly active catalysts to accelerate the reaction rate. Herein, NiO is reduced by cellulose through a hydrothermal method to obtain the highly active OER catalysts. The obtained cellulose‐partially‐reduced‐NiO (CL‐prNiO) shows a hybrid structure, composed of 3.6 wt.% face‐centered cubic (fcc) Ni and 96.4 wt.% rock salt structured NiO with highly disordered interface. The CL‐prNiO delivers a current density of 10 mA cm−2 with an overpotential of 288 mV, which is comparable to the commercial RuO2 and outperforms many of the recently reported Ni‐NiO based OER catalysts. As benefited from the hybrid and disordered structure, CL‐prNiO shows great ability of converting Ni2+ to Ni3+ at a potential prior to the OER onset. The in situ generated Ni3+ species can activate the lattice oxygen in the unreduced NiO of CL‐prNiO, significantly boosting the OER activity. [ABSTRACT FROM AUTHOR]

In this letter, a novel acousto-optical (AO) Q-switch is designed by using α-BaTeMo2O9 crystal grown by the flux method. The acousto-optical modulator (AOM) exhibits a high polarization extinction ratio of 65 dB with a rise time of 32.8 ns and insertion loss of 3.66 dB. An actively Q-switched ytterbium doped all fiber laser at 1035 nm is successfully realized by using the prepared AOM. Under a pump power of 404.9 mW, a maximum output power of 1.66 W is obtained with pulse width of 167 ns at the modulation rate of 10 kHz. The results show that the α-BaTeMo2O9 AOM is a potential Q-switch for all fiber lasers. [ABSTRACT FROM AUTHOR]

Niobium carbide (Nb2C), a newly developed 2D MXene material, has attracted much attention due to its outstanding electronic and optical properties. In this work, few‐layer 2D Nb2C nanosheets are synthesized by magnetron sputtering deposition method. Z‐scan measurements with pump source operating at 1.0 µm are performed to study the third‐order nonlinear optical response, revealing excellent light modulation capabilities of 2D Nb2C. The effective nonlinear absorption coefficient (βeff ≈ –105 cm GW–1) caused by saturable absorption effect is determined to be two orders of magnitude larger than that induced by reverse saturable absorption processes (two‐photon absorption, etc.). The positive nonlinear refractive index n2 is determined to be ≈10–13 m2 W–1 for the first time. Moreover, by decorating 2D Nb2C onto microfiber, microfiber‐based 2D Nb2C saturable absorber is fabricated and applied for compact square‐wave pulse mode‐locking ytterbium‐fiber laser. The pulse duration of SWP increases from 0.652 to 1.616 ns with the pulse energy increasing linearly up to 0.89 nJ while the peak power remains a constant. The results not only verify the capability of 2D Nb2C as an optical modulator, but also pave a new way for exploring SWP laser sources. [ABSTRACT FROM AUTHOR]

This work develops CoNi alloys with slight oxidation@N,O co-doped carbon (NOC) as multifunctional catalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) and Zn–air batteries. Their outer NOC shells have direct contributions to ORR, OER and HER activity that is dominated by N and O dopants that closely correlate with active adjacent C atoms. Meanwhile, the inner cores (CoNi alloys with slight oxidation) can provide indirect and important contributions. Relying on enhanced collective contributions of outer NOC shells and inner cores that are tuned by Co/Ni molar ratios, CoNi(1 : 1)-TB-800N2 with a Co/Ni molar ratio of 1 : 1 affords optimized multifunctional activity. Furthermore, it also brings about optimal Zn–air battery performance: ∼98.6% and ∼74.8% of theoretical specific capacity and energy density, respectively, and more than 100 h of stable charge–discharge operation at high current densities. [ABSTRACT FROM AUTHOR]

A new multi-functional crystal has been implemented by combining the acousto-optic (A/O) modulation with Raman laser output, which has never reported before. Notably, the $\alpha $ -BTM displaying an adequate A/O figure of merit of $10.18\times 10^{-18}\,\,\text{s}^{3}$ /g using the comparison method is originally tailored to fabricate an A/O modulator that exhibits a high diffraction angle and diffraction efficiency of 1.432° and 82.1% at 1064 nm, respectively, which can be competitive with that of TeO2. Pumped by a pulsed laser, sequentially, the self-Q-switch Raman laser working at 1178.1 nm is successfully realized based on $\alpha $ -BTM crystal. A maximum output power of 86 mW operating at 1178.1 nm and the repetition frequency of 15 kHz were obtained with the pump power of 27 W. Our works not only enrich the family of A/O materials, but also opens up a viable route towards exploiting the design of multi-functional crystal. [ABSTRACT FROM AUTHOR]

The global NH3 production is dominated by Haber–Bosch process, requiring high temperature and pressure. Electrochemical N2 reduction reaction (NRR) under ambient conditions is a greener path for artificial N2 fixation to NH3 but calling for efficient catalyst to increase activity and selectivity. Herein, we report the iron-based metal–organic frameworks (MOFs), i.e., MIL-88B–Fe and amine-functionalized MIL-88B–Fe (NH2–MIL-88B–Fe) as efficient catalysts for electrochemical NRR under ambient temperature and pressure in neutral electrolyte. NH2–MIL-88B–Fe shows higher NH3 yield rate of 1.205 × 10–10 mol s−1 cm−2 than MIL-88B–Fe (3.575 × 10–11 mol s−1 cm−2). Furthermore, NH2–MIL-88B–Fe exhibits the highest Faradaic efficiency of 12.45% at 0.05 V versus RHE. The control experiments prove that NH3 is produced through electrocatalytic NRR. This work may trigger the interest of using MOFs as highly efficient catalysts for electrochemical NH3 production. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) mono-elemental materials (Xenes) show remarkable potential in the fields of fundamental science and technology, have been regarded as a wide range of building blocks for electronic technologies due to their unique chemical, physical, electrical, and optical properties. Here, 2D tellurene/black phosphorus (Te/BP) heterojunctions are successfully fabricated through liquid-phase exfoliation (LPE) method. Their nonlinear optical absorption properties at 1.0, 2.0, and 2.8 μm have been studied by an open-aperture Z-scan method. The results revealed the excellent broadband saturable absorption responses of the prepared BP/Te heterojunctions, which are further confirmed by using them as saturable absorbers (SAs) for passively Q-switched all-solid-state lasers operating at 1.0, 2.0, and 2.8 μm, respectively. In particular, 1.04 μm continuous-wave (CW) mode-locked lasers with a pulse width of 404 fs is realized for the first time, to our best knowledge. Our work indicates that 2D Xenes especially 2D Xenes based heterojunctions have great potential in the fields of pulsed laser generation/modulation and other optoelectronic and photonic devices. [ABSTRACT FROM AUTHOR]

Summary A series of NiSFeS/N, S co‐doped carbon (NixFeyS/NSC) for electrochemical oxygen evolution reaction (OER) were synthesized by a co‐precipitation method and followed by pyrolysis in N2 atmosphere. NiSFeS hybrid was uniformly integrated with N, S co‐doped carbon in NixFeyS/NSC. NixFeyS/NSC showed high OER catalytic activity, and the optimized Ni60Fe40S/NSC afforded an OER overpotential of ~239 mV to deliver a current density of 10 mA cm−2 and showed a corresponding Tafel slope of ~30.9 mV dec−1 in 1 M KOH. Such OER catalytic activity was not only higher than that of IrO2, but also comparable with that of the most recently reported NiFe‐based sulfides for OER. Further study indicated that hybridizing NiS with FeS resulted in a synergistic effect for OER. The hybridization increased total amount of sulfides as active species, therefore enhancing the OER catalytic activity. In addition, the hybridization benefited the formation of petal‐like morphologies that contributing much to higher electrochemically active surface area (ECSA), and also boosted the content of graphitic and N, S co‐doped carbon that improving charge transfer efficiency. [ABSTRACT FROM AUTHOR]

Developing earth-abundant highly efficient catalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is indispensable for the widespread implementation of electrochemical water splitting to store renewable energy. Herein, amorphous bimetallic selenide (Ni–Fe–Se) hollow nanospheres electrodeposited on nickel foam (Ni–Fe–Se/NF) are developed as a bifunctional catalyst for the HER and OER. The HER and OER bifunctional activity of Ni–Fe–Se/NF outperforms those of monometallic Ni–Se/NF and Fe–Se/NF owing to the synergy of Ni and Fe in Ni–Fe–Se/NF. Moreover, the amorphous hollow spherical morphology of Ni–Fe–Se/NF increases the active site density and facilitates the mass transfer of electrolytes and H2/O2 products. Ni–Fe–Se/NF drives a current density of 10 mA cm−2 with an overpotential of ∼85 mV for the HER and 100 mA cm−2 with an overpotential of ∼222 mV for the OER. As the HER and OER bifunctional catalyst, Ni–Fe–Se/NF can split alkaline water with total voltages of ∼1.52 V and ∼1.66 V at 10 mA cm−2 and 100 mA cm−2, respectively, and remain stable over 50 hours of operation in 1 M KOH. [ABSTRACT FROM AUTHOR]

Non-precious bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play a pivotal role in regenerative fuel cells and rechargeable metal–air batteries. In this contribution, less active CeO2 is introduced for regulating the ORR/OER bifunctional activity of Co3O4@N-doped carbon (NC). The introduced CeO2 plays essential roles in increasing the surface contents of Co2+, Co3+ and N species in CeO2/Co3O4@NC for ORR/OER processes, while still maintaining hierarchical porosity and large specific surface area. Furthermore, the surface acid–base properties for the adsorption of oxygen molecules (for the ORR) and activation of water molecules (for the OER) and the charge transfer efficiency are also improved by the introduced CeO2. As a result, significantly enhanced ORR/OER bifunctional activity is achieved for the optimal and desired electrocatalyst, i.e., CeO2/Co3O4@NC. Its bifunctional activity is comparable or even superior to that of the benchmarked 20 wt% Pt/C (for the ORR) and IrO2 (for the OER), respectively. In the applications of Zn–air batteries, the battery with CeO2/Co3O4@NC still exhibits higher performance than the battery with mixed 20 wt% Pt/C + IrO2, due to its outstanding bifunctional activity toward the ORR and OER. [ABSTRACT FROM AUTHOR]

In this study, a β-Mo2C/N, P-co-doped carbon (NPC) catalyst with a porous structure of β-Mo2C nanoparticles loading on NPC matrix was prepared by vacuum-rotary evaporation and followed by a facile pyrolysis process for hydrogen evolution reaction (HER). The porous structure is beneficial for exposing more active sites and the mass transfer during the HER. In addition, the carbon matrixes with the highly doped N and P heteroatoms also provide their positive contributions to its high catalytic activity for HER. Owing to the advantages mentioned above, the optimized catalyst shows a small overpotential of 181 mV for driving a cathodic current density of 10 mA cm−2, a low Tafel slope of 65.3 mV dec−1 and a high exchange current density of 1.5 × 10−2 mA cm−2 during HER processes in acid electrolyte. The excellent performance of the β-Mo2C/NPC makes it a great potential candidate as the HER electrocatalyst. [ABSTRACT FROM AUTHOR]

A ternary transitional metal dichalcogenides alloy material, molybdenum sulphoselenide (MoSSe), has been successfully fabricated and used as a saturable absorber (SA) for a passively Q-switched (PQS) Tm:YAP bulk laser operating at $2.0~\mu \text{m}$ for the first time, to best of our knowledge. The open aperture Z-scan method was used to characterize the saturable absorption properties of the prepared MoSSe SA. The maximum average output power and pulse repetition rate, shortest pulse width, highest single pulse energy, and highest pulse peak power of this laser were 2.26 W, 95 kHz, 303 ns, $24.2~\mu \text{J}$ , and 80 W, respectively. The results are distinguished from other two-dimensional materials-based $2.0~\mu \text{m}$ PQS lasers, indicating that MoSSe could be a promising material for generating high power and short pulse width lasers in the $2.0~\mu \text{m}$ spectral range. [ABSTRACT FROM AUTHOR]

Metal-organic-frameworks (MOFs) (i.e., MOF(Fe), MOF(Co) and MOF(Cu)) were synthesized by a hydrothermal process. The prepared MOFs were characterized using X-ray diffraction, Fourier transform infrared spectroscopy and N adsorption-desorption. The catalytic activities of the MOFs for the electrochemical synthesis of ammonia were evaluated when using N (air) and water as raw materials at low temperature and ambient pressure. The results indicated that the prepared MOFs have fine crystalline structures, abundant micropores, and large specific surface areas. The prepared MOFs showed excellent catalytic activity for the electrochemical synthesis of ammonia at low temperature and ambient pressure. Among these MOFs, the MOF(Fe) displayed the best catalytic activity, and the highest ammonia formation rate and the highest current efficiency reached 2.12 × 10 mol s cm and 1.43%, respectively, at 1.2 V and 90 °C, when using pure N and water as raw materials. The prepared MOFs in this work showed remarkable catalytic activities for the electrochemical synthesis of ammonia at low temperature and ambient pressure among the non-noble metal catalysts. It was the first exploration to apply MOFs as the electrocatalysts for the electrochemical synthesis of ammonia at low temperature and ambient pressure. [ABSTRACT FROM AUTHOR]

An ε-MnO2/metal–organic-framework (Fe) (i.e., ε-MnO2/MOF(Fe)) composite was synthesised by integrating ε-MnO2 and a MOF(Fe) support. The composite was characterised using X-ray diffraction, N2 adsorption–desorption, field emission scanning electron microscopy, transmission electron microscopy, elemental mapping, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The ORR activity of the composite was evaluated by cyclic and linear sweep voltammetries in an alkaline electrolyte. The results revealed that in the ε-MnO2/MOF(Fe) composite, ε-MnO2 is in the form of nanorods, each with one end protruding and the other firmly anchored on the MOF(Fe) matrix with a high porosity and a high specific surface area. This unique structure of the composite is advantageous for oxygen diffusion and contact with ε-MnO2 during reactions, resulting in much better ORR activity and stability than those of ε-MnO2 in an alkaline electrolyte. The ε-MnO2/MOF(Fe)-catalysed ORR favours an apparent 4-electron transfer pathway in which oxygen was first reduced to hydroperoxide, which was further chemically decomposed into primarily OH− and O2. [ABSTRACT FROM AUTHOR]