Lasers Research Articles

Magnesium-promoted rapid self-reconstruction of NiFe-based electrocatalysts toward efficient oxygen evolution

The acceleration of active sites formation through surface reconstruction is widely acknowledged as the crucial factor in developing high-performance oxygen evolution reaction (OER) catalysts for water splitting. Herein, a simple one-step corrosion method and magnesium (Mg)-promoted strategy are reported to develop the NiFe-based catalyst with enhanced OER performance. The Mg is introduced in NiFe materials to preparate a “pre-catalyst” Mg-Ni/Fe2O3. In-situ Raman shows that Mg doping would accelerate the self-reconstruction of Ni/Fe2O3 to form active NiOOH species during OER. In-situ infrared indicates that Mg doping benefits the formation of *OOH intermediate. Theoretical analysis further confirms that Mg doping can optimize the adsorption of oxygen intermediates, accelerating the OER kinetics. Accordingly, the Mg-Ni/Fe2O3 catalyst exhibits excellent OER performance with overpotential of 168 mV at 10 mA cm−2. The anion exchange membrane water electrolyzer achieved 200 mA cm−2 at voltage of 1.53 V, showing excellent stability over 500 h as well. This work demonstrates the potential of Mg-promoted strategy in regulating the activity of transition metal-based OER electrocatalysts.

Promotion of Different Active Phases in MnOX-CeO2 Catalysts for Simultaneous NO Reduction and o-DCB Oxidation

AbstractMnOX-CeO2 catalysts with different Mn and Ce content were prepared to evaluate the effect of metal content on catalytic properties and activity in the simultaneous NO reduction and o-DCB oxidation, in order to elucidate the most active species for the process. Catalytic properties were evaluated by ICP-AES, XRD, skeletal FTIR, STEM-HAADF, XPS, N2-physisorption, H2-TPR, NH3-TPD and pyridine-FTIR. Catalysts with 85%Mn and 15%Ce molar content have been found to be the most active. Their excellent catalytic performance is related to the coexistence of Mn in different phases, i.e., Mn species strongly interacting with Ce and segregated Mn species. The effect of the preparation methods has also been deeply investigated: Co-precipitation method (CP) leads to Mn segregation as Mn2O3, whereas sol-gel preparation method (SG) promotes the formation of an amorphous powder. The synergy between segregated Mn2O3 species and Mn species in high interaction with Ce (resulting in a mixed oxide phase) leads to the presence of Mn with different oxidation states. This effect, together with the high oxygen mobility caused by structural defects, enhances redox, acidic and oxidative properties. The improvement of catalytic properties with Mn content also favors NO reduction side-reactions, with N2O and NO2 being the most important by-products, whereas it limits the production of chlorinated organic by-products in o-DCB oxidation.

Crystal Facets-Activity Correlation for Oxygen Evolution Reaction in Compositional Complex Alloys.

Compositional complex alloys, including high and medium-entropy alloys (HEAs/MEAs) have displayed significant potential as efficient electrocatalysts for the oxygen evolution reaction (OER), but their structure-activity relationship remains unclear. In particular, the basic question of which crystal facets are more active, especially considering the surface reconstructions, has yet to be answered. This study demonstrates that the lowest index {100} facets of FeCoNiCr MEAs exhibit the highest activity. The underlying mechanism associated with the {100} facet's low in-plane density, making it easier to surface reconstruction and form amorphous structures containing the true active species is uncovered. These results are validated by experiments on single crystals and polycrystal MEAs, as well as DFT calculations. The discoveries contribute to a fundamental comprehension of MEAs in electrocatalysis and offer physics-based strategies for developing electrocatalysts.

Efficient removal of plasticiser dibutyl phthalate on CoP cluster anchored MXene via boosting peroxymonosulfate activation: Catalytic performance and decomposition mechanism

A novel Ti3C2 synthesis method via strong alkaline etching (MXeneba) was developed to degrade dibutyl phthalate (DBP) using a CoP/MXeneba + peroxymonosulfate (PMS) system. The MXeneba's modified surface properties enabled stable Co2+ adsorption and homogeneous loading of ultrasmall CoP clusters post-phosphatisation. Complete DBP degradation was achieved within 30 min, facilitated by reactive oxygen species (ROS: SO4·-, ·OH, O2·-, and 1O2) and the highly reduced titanium atoms promoting Co3+ to Co2+ conversion. Density functional theory (DFT) calculations elucidated PMS adsorption sites and active species for DBP degradation. This study clarifies the activation mechanism, linking catalyst structure to performance, and provides insights for future advanced oxidation processes in environmental remediation. The findings emphasize the practical application and significance of the CoP/MXeneba catalyst in treating harmful plasticisers in water, contributing to efficient and sustainable water purification methods. The research also highlights this novel catalyst system's robustness and versatility in tackling diverse pollutants.

Complex and highly saturated soundscapes in restored oak woodlands reflect avian richness and abundance.

Temperate woodlands are biodiverse natural communities threatened by land use change and fire suppression. Excluding historic disturbance regimes of periodic groundfires from woodlands causes degradation, resulting from changes in the plant community and subsequent biodiversity loss. Restoration, through prescribed fire and tree thinning, can reverse biodiversity losses, however, because the diversity of woodland species spans many taxa, efficiently quantifying biodiversity can be challenging. We assessed whether soundscapes in an eastern North American woodland reflect biodiversity changes during restoration measured in a concurrent multitrophic field study. In five restored and five degraded woodland sites in Wisconsin, USA, we sampled vegetation, measured arthropod biomass, conducted bird surveys, and recorded soundscapes for five days of every 15-day period from May to August 2022. We calculated two complementary acoustic indices: Soundscape Saturation, which focuses on all acoustically active species, and Acoustic Complexity Index (ACI), which was developed to study vocalizing birds. We used generalized additive models to predict both indices based on Julian date, time of day, and level of habitat degradation. We found that restored woodlands had higher arthropod biomass, and higher richness and abundance of breeding birds. Additionally, soundscapes in restored sites had higher mean Soundscape Saturation and higher mean ACI. Restored woodland acoustic indices exhibited greater magnitudes of daily and seasonal peaks. We conclude that woodland restoration results in higher soundscape saturation and complexity, due to greater richness and abundance of vocalizing animals. This bioacoustic signature of restoration offers a promising monitoring tool for efficiently documenting differences in woodland biodiversity.

Carbonate radicals mediated catalytic degradation of antibiotics over earth-abundant BaCO3-based system: Performance, mechanism and calculation

The semiconductor-insulator heterostructure, characterized by outstanding economic-efficiency and catalytic activity, represents a promising photocatalyst for practical pollutants degradation. However, achieving energy band matching between semiconductors and insulators remains a challenge. In this study, we meticulously designed and synthesized a band-matched semiconductor-insulator photocatalysts (AgI-BaCO3), leveraging the in-situ nucleation of ultrafine AgI nanoparticles on BaCO3 surface. The finely crafted heterostructure notably enhanced degradation efficiency of tetracycline over both pure AgI and BaCO3, demonstrating a remarkable pseudo-first-order kinetic rate constant that surpassed them by 27.2 and 33.5 times, respectively. The density functional theory calculations uncovered that the intense covalent interaction between AgI and BaCO3 established a specific channel for interfacial charge carriers. The generated CO3·- radicals as the main active species markedly expedited the removal of antibiotics. Furthermore, the catalysts demonstrated robust activity in real wastewater and surface water. This work supplies a novel reference for constructing insulator-based photocatalysts and elucidates its potential application in actual aquatic environments.

W single-atom mediated singlet oxygen formation on carbon nitride for powerful photocatalytic abatement of organic pollutants

Active single-atom W anchoring on graphitic carbon nitride (g-C3N4) with interplanar four-coordination with N was achieved via a microwave hydrothermal process followed by thermal polymerization. The optimal monoatomic W incorporated g-C3N4 (W-CN) catalyst exhibited a high photocatalytic activity toward a wide range of pharmaceutical and personal care products (PPCPs). The anchoring of W single atom narrowed the energy-band, negatively shifted the conduction band of g-C3N4, and promoted the charge transfer and photogenerated carrier separation. Moreover, W single-atom intercalation obviously favored the formation of singlet oxygen (1O2), as validated by the active species capture test and density functional theory (DFT) calculation, which played an important role in the photocatalytic degradation of PPCPs. The treatment of actual wastewater, toxicity assessment and hemp-pea-growth experiments further showed that the W-CN photocatalyst could effectively degrade the organic pollutants and reduce their poisonousness in the water environment. This work offers a facile route to obtain reactive g-C3N4 with single-metal active sites and some insights into its activity enhancement for the abatement of organic pollutant-containing wastewater.

Enhanced photocatalytic performance of NiFe2O4/ZnIn2S4 p-n heterojunction for efficient degradation of tetracycline

The persistent release of tetracycline into the environment significantly endangers both ecosystems and human health. Zinc indium sulfide (ZnIn2S4) capable to degrade tetracycline pollutants under visible light irradiation has attracted extensive attentions and great effort has been devoted to augment its catalytic efficacy. In this work, we synthesized a p-n heterojunction, NiFe2O4/ZnIn2S4, to enhance the carrier migration rate and explained the intrinsic mechanism by density functional theory. When the heterojunction was formed, carriers traversed from the n-type NiFe2O4 to the p-type ZnIn2S4, instigating the emergence of a built-in electric field to facilitate the separation of carriers. 2 %-NiFe2O4/ZnIn2S4 exhibited excellent photocatalytic efficiency in tetracycline (TC) degradation and total organic carbon (TOC) removal. Compared to pure ZnIn2S4 and NiFe2O4, the TC degradation rates of 2 %-NiFe2O4/ZnIn2S4 were 2.0 times and 16.9 times higher, respectively. Additionally, 2 %-NiFe2O4/ZnIn2S4 had a saturation magnetization intensity of 3.05 emu/g, allowing for rapid recovery of the catalyst under a magnetic field. Superoxide radicals (O2−) and holes (h+) were the primary active species driving the degradation process. Furthermore, potential reaction pathways of tetracycline in this photocatalytic process were determined and bioconcentration factor and developmental toxicity of the intermediate products were accessed. This work held great potentials for wastewater treatment and provided a pathway for the development of magnetic recyclable photocatalysts.

Regulation of oxygen vacancies in MnCO3-based catalysts by thermally inducing for efficiently catalytic benzene combustion

Tuning oxygen vacancies through carbon pyrolysis is an effective strategy for fabricating high-performance catalysts to oxidize volatile organic compounds (VOCs). Herein, a series of MnCO3-based catalysts were synthesized by pyrolyzing MnCO3 precursors with different morphologies including dumbbell-like (D), bayberry-like (B) and cubic (C) structures for the benzene oxidation. The catalyst (D-300) derived from dumbbell-like MnCO3 exhibited superior catalytic performance for the benzene oxidation with a T90 of 176 °C and remarkable stability in long-term, cycling and water-resistance tests. Abundant oxygen vacancies in D-300 improved lattice oxygen mobility and redox ability, resulting in superior oxygen uptake and release capabilities. Moreover, oxygen vacancies greatly facilitated the activation and replenishment of gaseous oxygens to generate active oxygen species, thereby dramatically accelerating the cleavage of benzene rings and deep mineralization. In situ DRIFTS analysis demonstrated that benzene preferentially adsorbed onto D-300 due to its abundant acidic sites, and the oxidation of phenolate species was a rate-determining step. H2O may hinder the activation of gaseous oxygen, suppressing the activity of the catalyst.

Photocatalytic degradation of methyl orange by a Pt(II) complex under visible light irradiation

An extremely effective photocatalytic complex, PtLCl2 (1), was synthesized with (4-([2,2':6',2''-terpyridin]-4'-yl)phenyl)boronic acid as ligand and further characterized through single crystal X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis spectrum. Multipoint hydrogen bonds and three kinds of π-π stacking interactions are observed in the supramolecular structure of 1. More significantly, the Pt(II) complex exhibits outstanding photocatalytic degradation efficiency (94.76%) for methyl orange within 120 min under visible light irradiation. The kinetic rate constant (k) for 1 (10 mg) is 0.02505 min−1, which is approximately 70 times higher than that of the ligand (0.00036 min−1). Moreover, its photocatalysis mechanism proposed that ·O2 − and h+ were the main active species for MO degradation, providing a great prospect for development of a new efficient photocatalytic complex.

Synthesis of 2,4,6‐Triaryl‐1,3,5‐triazines via the Cyclotrimerization of Benzonitriles with Catalytic Systems Composed of Titanium Chlorido Complexes and Magnesium

The catalytic activity of low‐valent transition metals for the cyclotrimerization of nitriles has rarely been investigated to date. Here, we report on the cyclotrimerization of benzonitrile (PhCN) and its derivatives using catalytic systems composed of magnesium and bis(indolyl)TiCl2 (bis(indolyl) = di(3‐methylindol‐2‐yl)phenylmethane), Cp2TiCl2 (Cp = η5‐C5H5), (CGC)TiCl2 (CGC = Me2Si(Me4C5)(tBuN)), TiCl4(thf)2 (thf = tetrahydrofuran), Cp*TiCl3 (Cp* = η5‐Me5C5), or CpTiCl3, which can be expected to generate coordinatively unsaturated Ti(II) complexes as the catalytically active species. All the investigated catalytic systems were active for the cyclotrimerization of PhCN. Notably, even the simple catalytic precursor (TiCl4(thf)2) mediated the cyclotrimerization of PhCN as well as p‐ and m‐tolunitriles. Moreover, these reactions can be carried out on the gram scale and the cyclotrimerized products can be isolated via recrystallization of the reaction mixture from hot toluene. The findings of this study suggest that low‐valent titanium species have the potential to serve as catalysts for the cyclotrimerization of PhCN and its derivatives. During this study, we also found that 2,4,6‐tri(p‐tolyl)‐1,3,5‐triazine, which is obtained from the cyclotrimerization of p‐tolunitrile, exhibits fluorescent properties in both the solid state and in solution.

Photocatalytic degradation of tetracycline by g-C3N4/stilbite under visible light: Mechanistic insights and degradation pathways

In this study, the g-C3N4/stilbite composite was fabricated by the in-situ synthesis method, and the photocatalytic performance was investigated by degrading tetracycline (TC) under visible light. The results indicated that the photocatalytic degradation efficiency of g-C3N4/stilbite-6 (86.8 %) was about 2.7 times higher than that of pure g-C3N4 (31.8 %). The introduction of the stilbite carrier effectively resolved the issues of g-C3N4 such as easy self-agglomeration and the difficulty in separating photo-generated carriers, thereby improving the photocatalytic activity of g-C3N4. From the quenching experiment, it was found that h+ and •O2− were main active species for TC degradation. By HPLC-MS analysis, TC degradation products were identified, and three degradation pathways were proposed. In addition, the impacts of solution pH, light intensity, and catalyst dosage on TC degradation performance were also evaluated. Overall, a simple and successful strategy has been proposed to synthesize high-performing visible-light-driven photocatalysts for efficiently eliminating organic contaminants from wastewater.

Synergistic photocatalytic performance of MoO3:Cu/g-C3N4 heterojunction semiconductor for efficient crystal violet dye degradation: A sustainable approach for environmental remediation

A heterojunction semiconductor of MoO3:Cu in conjunction with g-C3N4 was fabricated using a green synthesis approach facilitated by leaves extract of Murraya paniculata. Numerous methods of characterisation, including XPS, FTIR spectroscopy, XRD, BET, HR-TEM, FE-SEM, EDAX, and UV–visible spectrophotometry were employed to analyse the materials. The results from XRD and HRTEM indicated the highly crystalline nanoparticles with a mean particle size of 5.42 nm for MoO3 nanomaterials with doping of 5.62 nm Cu particles. The two-dimensional g-C3N4 sheeted structure acted as a translucent layer, facilitating self-assembly on the spherical MoO3:Cu nanoparticles, thereby promoting efficient charge flow and enhancing the photodegradation capability of the heterojunction semiconductor. XPS analysis confirmed the presence of Mo, Cu, N, O, and C in the fabricated heterojunction. UV–Visible and PL spectra demonstrated the efficient suppression of exciton annihilation in the heterojunction semiconductor. Remarkably, the heterojunction exhibited a high photocatalytic degradation performance of 97 % for the photodegradation of Crystal violet (CV) dye. Additionally, the effects of pH and dose of catalyst on photodegradation, as well as the recyclability of the catalyst, were evaluated. Kinetic analysis revealed a pseudo first-order reaction with 0.617 min−1 rate constant, while scavenger experiments confirmed the involvement of h+ and .O2− as active species in the degradation process.

Construction of a BiOCl/Bi2O2CO3 S-Scheme Heterojunction Photocatalyst via Sharing [Bi2O2]2+ Slabs with Enhanced Photocatalytic H2O2 Production Performance.

The construction of a close contact interface is key to enhancing the photocatalytic activity in heterojunctions. In the work, the BiOCl/Bi2O2CO3 of sharing [Bi2O2]2+ slabs S-scheme heterojunction was prepared by a HCl in situ etching method. The optimal composite photocatalyst could accomplish sizable productivity of H2O2 to 2562.95 μmol g-1 h-1 under simulated solar irradiation, higher than that of primitive Bi2O2CO3 and BiOCl. Moreover, the synthesized catalysts showed good stability. The band structures of BiOCl and Bi2O2CO3 were determined, confirming the formation of BiOCl/Bi2O2CO3 S-scheme heterojunction The BiOCl/Bi2O2CO3, which obviously improved the separation efficiency of photoinduced carriers and effectively enhanced the redox ability of the photocatalyst. In addition, density functional theory (DFT) calculations were utilized to analyze the electron transfer properties and the constitution of the built-in electric field at the interface of BiOCl and Bi2O2CO3. The photocatalytic reaction process was further researched by electron paramagnetic resonance (EPR), indicating the active species in the photocatalytic production of hydrogen peroxide. Eventually, a feasible S-scheme electron transfer mechanism on the BiOCl/Bi2O2CO3 heterojunction during the photocatalytic H2O2 production process was proposed and discussed. This work provides a reliable strategy for the fine design of the S-scheme heterojunction.

Regulation of reactive species during ionizing radiation by peroxydisulfate for enhanced degradation of typical pollutants in coking wastewater

This study focused on exploring the effect of peroxydisulfate (PDS) on the regulation of reactive species during water radiolysis process and its potential application for degrading organic pollutants. The results indicated that PDS was successfully activated by ionizing radiation for efficient removal of three typical phenolic compounds over a wide pH range (3.0∼12.0) at absorbed dose of 5 kGy. Chemical probe methods provided the evidence that the addition of PDS could introduce the sulfate radicals (SO4•−) and enhance the production of hydroxyl radicals (•OH). According to the quenching tests, •OH and SO4•− were the dominant reactive species responsible for the degradation of 4-NP, while hydrated electron (eaq−) played a minor role. The regulatory effect of PDS on active species in the ionizing radiation process could divided by (i) PDS could be directly activated by ionizing radiation to produce •OH and SO4•− via energy transfer pathway; (ii) PDS could boost the conversion of eaq− to SO4•− via electron transfer pathway. Furthermore, we assessed the applicability of the IR and IR/PDS systems in treating mixed solutions containing various pollutants and actual coking wastewater.

A Combination of Remote Sensing Datasets for Coastal Marine Habitat Mapping Using Random Forest Algorithm in Pistolet Bay, Canada

Marine ecosystems serve as vital indicators of biodiversity, providing habitats for diverse flora and fauna. Canada’s extensive coastal regions encompass a rich range of marine habitats, necessitating accurate mapping techniques utilizing advanced technologies, such as remote sensing (RS). This study focused on a study area in Pistolet Bay in Newfoundland and Labrador (NL), Canada, with an area of approximately 170 km2 and depths varying between 0 and −28 m. Considering the relatively large coverage and shallow depths of water of the study area, it was decided to use airborne bathymetric Light Detection and Ranging (LiDAR) data, which used green laser pulses, to map the marine habitats in this region. Along with this LiDAR data, Remotely Operated Vehicle (ROV) footage, high-resolution multispectral drone imagery, true color Google Earth (GE) imagery, and shoreline survey data were also collected. These datasets were preprocessed and categorized into five classes of Eelgrass, Rockweed, Kelp, Other vegetation, and Non-Vegetation. A marine habitat map of the study area was generated using the features extracted from LiDAR data, such as intensity, depth, slope, and canopy height, using an object-based Random Forest (RF) algorithm. Despite multiple challenges, the resulting habitat map exhibited a commendable classification accuracy of 89%. This underscores the efficacy of the developed Artificial Intelligence (AI) model for future marine habitat mapping endeavors across the country.

Tetragonal/orthorhombic phase Bi2WO6 homojunction for photoelectrochemical degradation of rhodamine B with high efficiency

Photoelectrochemical (PEC) degradation of organic pollutants to CO2 and H2O is a promising strategy to solve the growing environmental problems. Bismuth tungstate (Bi2WO6) has attracted much attention due to its good chemical stability and moderate conduction band valence band position. However, the PEC activity of Bi2WO6 catalysts is greatly limited due to its rapidly complex electron-hole. This article reports a rational low-cost design that successfully prepares tetragonal/orthorhombic Bi2WO6 homojunction on FTO conductive glass substrates through a simple two-step solvothermal method, significantly enhancing the PEC performance. The study investigated the effectiveness of photoelectrochemical degradation of the recalcitrant organic pollutant Rhodamine B (RhB) and conducted an in-depth exploration of the photoelectrocatalytic reaction process and mechanism. The experimental results indicate that the homojunction achieves a degradation rate of up to 100 % for the recalcitrant organic pollutant RhB within 30 minutes, significantly surpassing that of single-phase Bi2WO6, and at the same time the sample maintains good stability after five cycles of operation. Further analysis of the capture experiments indicates that holes (h+) and superoxide radicals (·O2⁻) are the primary active species responsible for RhB degradation. This study not only provides new insights into the design of high-efficiency photoelectrode, but also offers new solutions for environmental pollution control.

Photocatalytic degradation of antibiotics by N-doped carbon nanoflakes-nickel ferrite composite derived from algal biomass

This work reports the synthesis of nickel ferrite (NiFe) nanoparticles, N-doped mesoporous carbon nanoflakes (NCF) and novel nickel ferrite-carbon nanoflakes (NiFe@NCF) nanocomposite using solvothermal method. NCF was derived from a cyanobacterial consortium consisting of Anabaena, Lyngbya and Weistiellopsis, rich in carbon and nitrogen. The synthesized nanoparticles were used as heterogeneous photocatalyst for degradation of two harmful water pollutants, ciprofloxacin (CIP) and levofloxacin (LEV). 99.91% LEV and 98.86% CIP were degraded within 50 and 70 min of visible light irradiation using NiFe@NCF following pseudo first order kinetics. This improved efficiency of the nanocomposite may be attributed to its higher surface area, reduction of band gap (from 2.42 to 2.19 eV), more active sites as well as charge carrier mobility with decreasing agglomeration tendency of the magnetic nickel nanoparticles upon being embedded on NCF. N-doping improves light harvesting property, retards charge recombination and extends as well as delocalises ᴨ-conjugated system resulting in enhanced photocatalytic activity. The scavenging experiments and EPR analysis reveal that O2−• and •OH are the main active species taking part in the degradation process. The material performs well within a wide range of pH and can be effectively used up to 5 repetitive cycles. A feasible photocatalytic degradation mechanism of the antibiotics against NiFe@NCF nanocomposite is also put forwarded along with their possible degradation pathways from LCMS studies.

Construction of multifunctional interface engineering on Cu‐SSZ‐13@Ce‐MnOx/Mesoporous-silica catalyst for boosting activity, SO2 tolerance and hydrothermal stability

Although small pore Cu-SSZ-13 catalysts have been successful as commercial catalysts for controlling NOx emissions from mobile sources, the challenges of high light-off temperature, SO2 tolerance and hydrothermal stability still need to be addressed. Here, we synthesized a multifunctional core-shell catalyst with Cu-SSZ-13 as the core phase and Ce-MnOx supported Mesoporous-silica (Meso-SiO2) as the shell phase via self-assembly and impregnation. The core-shell catalyst exhibited excellent low-temperature activity, SO2 tolerance and hydrothermal stability compared to the Cu-SSZ-13. The Ce-MnOx species dispersed in the shell are found to enhance both the acidic and oxidative properties of the core-shell catalyst. More critically, these species can rapidly activate NO and oxidize it to NO2, which allows the NH3-SCR reaction on the core-shell catalyst to be initiated in the shell phase. Meanwhile, Ce-MnOx species can react preferentially with SO2 as sacrifice components, effectively avoiding the sulfur inactivation of the copper active sites. Furthermore, the hydrophobic Meso-SiO2 shell provides an important barrier for the core phase, which reduces the loss of active species, acid sites and framework Al of the aged core-shell catalyst and mitigates the collapse of the zeolite framework. This work provides a new strategy for the design of novel and efficient NH3-SCR catalysts.

High-power single-longitudinal-mode visible Pr:YLF ring lasers

We present the development and characterization of high-power single-longitudinal-mode (SLM) Pr:YLF lasers across the visible spectrum using a ring cavity design integrated with an optical diode (OD) and Fabry-Perot etalons. Our study achieved notable single-frequency outputs at 639 nm (red), 604 nm, and 607 nm (orange), and 522 nm (green). Specifically, we obtained a maximum output of 1.4 W at 639 nm, while the orange lasers produced outputs of 435 mW at 604 nm and 1.03 W at 607 nm. The green laser achieved a maximum output of 313 mW at 522 nm. The narrowest linewidths recorded were 7.8 MHz for red, 9.4 MHz and 7.6 MHz for orange, and 9.7 MHz for green. These results demonstrate the feasibility of using a ring cavity combined with an F-P etalon to achieve high-power, narrow-linewidth SLM operation across a significant portion of the visible spectra, offering potential applications in precision spectroscopy, optical communications, and metrology.