Deciphering Indirect Nitrite Reduction to Ammonia in High-Entropy Electrocatalysts Using In Situ Raman and X-ray Absorption Spectroscopies

This research adopts a new method combining calcination and pulsed laser irradiation in liquids to induce a controlled phase transformation of Fe, Co, Ni, Cu, and Mn transition-metal-based high-entropy Prussian blue analogs into single-phase spinel high-entropy oxide and face-centered cubic high-entropy alloy (HEA). The synthesized HEA, characterized by its highly conductive nature and reactive surface, demonstrates exceptional performance in capturing low-level nitrite (NO2 -) in an electrolyte, which leads to its efficient conversion into ammonium (NH4 +) with a Faradaic efficiency of 79.77% and N selectivity of 61.49% at -0.8 V versus Ag/AgCl. In addition, the HEA exhibits remarkable durability in the continuous nitrite reduction reaction (NO2 -RR), converting 79.35% of the initial NO2 - into NH4 + with an impressive yield of 1101.48 µm h-1 cm-2. By employing advanced X-ray absorption and in situ electrochemical Raman techniques, this study provides insights into the indirect NO2 -RR, highlighting the versatility and efficacy of HEA in sustainable electrochemical applications.

Laser-Synthesized Ru-Anchored Few-Layer Black Phosphorus for Superior Hydrogen Evolution: Role of Acoustic Levitation

Electrochemical water splitting, driven by processed catalysts, is the most reasonable method for hydrogen production. This study demonstrates an activation phenomenon with ruthenium (Ru) nanoclusters on few-layered black phosphorus (BP), greatly enhancing the electrocatalytic hydrogen evolution reaction (HER). Efficient BP exfoliation was achieved using acoustic levitators and pulsed laser irradiation in liquids (PLIL), yielding charge-transfer Ru-nanoclusters on modulated surfaces. Various PLIL parameters were examined for the optimal BP sheet size. After ruthenization, Ru's d-band center facilitated hydrogen adsorption via Ru-H bonding. Synergy between BP's charge-carrier properties and Ru's active sites boosted HER kinetics with an ultralow overpotential of 84 mV at 10 mA/cm2 in KOH. Additionally, the RuO2 || RuBP-2 electrolyzer demonstrated remarkable overall water splitting performance at ∼1.60 V at 10 mA/cm2. These results highlight the pivotal role of metal nanoclusters on exfoliated BP surfaces and offer a refined strategy for high-density electrocatalysts in energy conversion.

Laser-Synthesized Co-Doped CuO Electrocatalyst: Unveiling Boosted Methanol Oxidation Kinetics for Enhanced Hydrogen Production Efficiency by In Situ/Operando Raman and Theoretical Analyses

The present study details the strategic development of Co-doped CuO nanostructures via sophisticated and expedited pulsed laser ablation in liquids (PLAL) technique. Subsequently, these structures are employed as potent electrocatalysts for the anodic methanol oxidation reaction (MOR), offering an alternative to the sluggish oxygen evolution reaction (OER). Electrochemical assessments indicate that the Co-CuO catalyst exhibits exceptional MOR activity, requiring a reduced potential of 1.42 V at 10 mA cm-2 compared to that of pure CuO catalyst (1.57 V at 10 mA cm-2 ). Impressively, the Co-CuO catalyst achieved a nearly 180 mV potential reduction in MOR compared to its OER performance (1.60 V at 10 mA cm-2 ). Furthermore, when pairing Co-CuO(+)ǀǀPt/C(-) in methanol electrolysis, the cell voltage required is only 1.51 V at 10 mA cm-2 , maintaining remarkable stability over 12 h. This represents a substantial voltage reduction of ≈160 mV relative to conventional water electrolysis (1.67 V at 10 mA cm-2 ). Additionally, both in situ/operando Raman spectroscopy studies and theoretical calculations have confirmed that Co-doping plays a crucial role in enhancing the activity of the Co-CuO catalyst. This research introduces a novel synthetic approach for fabricating high-efficiency electrocatalysts for large-scale hydrogen production while co-synthesizing value-added formic acid.

Aloe vera-derived graphene-coupled phenosafranin photocatalyst for generation and regeneration of ammonia and NADH by mimicking natural photosynthetic route

Aloe vera-derived graphene (ADG) coupled system photocatalyst, mimicking natural photosynthesis, is one of the most promising ways for converting solar energy into ammonia (NH3 ) and nicotinamide adenine dinucleotide (NADH) that have been widely used to make the numerous chemicals such as fertilizer and fuel. In this study, we report the synthesis of the aloe vera-derived graphene-coupled phenosafranin (ADGCP) acting as a highly efficient photocatalyst for the generation of NH3 and regeneration of NADH from nitrogen (N2 ) and oxidized form of nicotinamide adenine dinucleotide (NAD+ ). The results show a benchmark instance for mimicking natural photosynthesis activity as well as the practical applications for the solar-driven selective formation of NH3 and the regeneration of NADH by using the newly designed photocatalyst.

In-situ monitoring of thiazine molecular aggregation in various solvents via a free-standing acoustic levitator

In this work, we explored the in-situ reaction modeling of the molecular self-aggregation of methylene blue (MB), which is a cationic thiazine dye, in different solvents via a container-less acoustic levitator by floating of a single droplet. Our in-situ spectroscopic study revealed that the dimer essentially has a sandwich structural geometry with a deviation from parallel stacking and horizontal arrangements in the molecular planes. The real time conversion of the monomer in MB into a dimer and their dynamics in water and ethanol media were monitored using a free-standing acoustic levitator droplet system. The absorption spectra revealed changes in the two resolved peaks (monomer and dimer) and orderliness when water and ethanol were used as the media. Interestingly, the enhancement in the dimerization of MB could be attributed to droplet evaporation, which is difficult to observe in typical reactor containers. Moreover, acidic protonation resulted in a change in the aggregation orientation direction of the MB molecules, forming an unusual J-aggregation. Theoretical DFT calculations revealed that MB underwent typical H-aggregation and J-aggregation in the different solvent environments, and their orientations well matched the spectroscopic data.

Formation of the C4Hn+ (n = 2-5) ions upon ionization of acetylene clusters in helium droplets

Infrared (IR) spectroscopy using ultracold helium nanodroplet matrices has proven to be a powerful method to interrogate encapsulated ions, molecules, and clusters. Due to the helium droplets' high ionization potential, optical transparency, and ability to pick up dopant molecules, the droplets offer a unique modality to probe transient chemical species produced via photo- or electron impact ionization. In this work, helium droplets were doped with acetylene molecules and ionized via electron impact. Ion-molecule reactions within the droplet volume yield larger carbo-cations that were studied via IR laser spectroscopy. This work is focused on cations containing four carbon atoms. The spectra of C4H2+, C4H3+, and C4H5+ are dominated by diacetylene, vinylacetylene, and methylcyclopropene cations, respectively, which are the lowest energy isomers. On the other hand, the spectrum of C4H4+ ions hints at the presence of several co-existing isomers, the identity of which remains to be elucidated.

Current trends and prospects in catalytic upgrading of lignocellulosic biomass feedstock into ultrapure biofuels

Eco-friendly renewable energy sources have recommended as fossil fuel alternatives in recent years to reduce environmental pollution and meet future energy demands in various sectors. As the largest source of renewable energy in the world, lignocellulosic biomass has received considerable interest from the scientific community to advance the fabrication of biofuels and ultrafine value-added chemicals. For example, biomass obtained from agricultural wastes could catalytically convert into furan derivatives. Among furan derivatives, 5-hydroxymethylfurfural (HMF) and 2, 5-dimethylfuran (DMF) are considered the most useful molecules that can be transformed into desirable products such as fuels and fine chemicals. Because of its exceptional properties, e.g., water insolubility and high boiling point, DMF has studied as the ideal fuel in recent decades. Interestingly, HMF, a feedstock upgraded from biomass sources can easily hydrogenate to produce DMF. In the present review, the current state of the art and studies on the transformation of HMF into DMF using noble metals, non-noble metals, bimetallic catalysts, and their composites have discussed elaborately. In addition, comprehensive insights into the operating reaction conditions and the influence of employed support over the hydrogenation process have demonstrated.

Moving beyond Ti2C3Tx MXene to Pt-Decorated TiO2@TiC Core-Shell via Pulsed Laser in Reshaping Modification for Accelerating Hydrogen Evolution Kinetics

Phase engineering of nanocatalysts on specific facets is critical not only for enhancing catalytic activity but also for intensely understanding the impact of facet-based phase engineering on electrocatalytic reactions. In this study, we successfully reshaped a two-dimensional (2D) MXene (Ti₃C₂T_x) obtained by etching Ti₃AlC₂ MAX via a pulsed laser irradiation in liquid (PLIL) process. We produced a TiO₂@TiC core-shell structure in spheres with sizes of 200-350 nm, and then ∼2 nm ultrasmall Pt NPs were decorated on the surface of the TiO₂@TiC core-shell using the single-step PLIL method. These advances allow for a significant increase in electrocatalytic hydrogen evolution reaction (HER) activity under visible light illumination. The effect of optimal Pt loading on PLIL time was identified, and the resulting Pt/TiO₂@TiC/Pt-5 min sample demonstrated outstanding electrochemical and photoelectrochemical performance. The photoelectrochemical HER activity over Pt/TiO₂@TiC/Pt-5 min catalyst exhibits a low overpotential of 48 mV at 10 mA/cm² and an ultralow Tafel slope of 54.03 mV/dec with excellent stability of over 50 h, which is hydrogen production activity even superior to that of the commercial Pt/C catalysts (55 mV, 62.45 mV/dec). This investigation not only serves as a potential for laser-dependent phase engineering but also provides a reliable strategy for the rational design and fabrication of highly effective nanocatalysts.

Electrochemical detection of arsenic (III) hazardous chemicals using cubic CsPbBr3 single crystals: Structural insights from DFT study

Long-term exposure to the highly toxic heavy metal arsenic can harm ecological systems and pose serious health risks to humans. Arsenic pollutant in water and the food chain must be addressed, and active prompt detection of As(III) is essential. The development of an effective detection method for As(III) ions is urgently needed to slow the alarming growth of arsenic pollution in the environment and safeguard the well-being of future generations. This study presents the results of our exhaustive investigation into cubic CsPbBr₃ single crystals, the glassy carbon (GC) electrode modification with CsPbBr₃ single crystals prepared by direct solvent evaporation, as well as our observations of the material's remarkable electrocatalytic properties and exceptional anti-interference sensing of As(III) ions in neutral pH media. The developed CsPbBr₃/GC is exceptionally useful for the ultra-sensitive and specific identification of arsenic in water, exhibiting a detection limit of 0.381 μmol/L, a rapid response across a defined range of 0.1-25 μmol/L, and an ultra-sensitivity of 0.296 μA/μmolL^-1. CsPbBr₃/GCE (prepared without a specific reagent) is superior to other modified electrodes used as sensors in electrocatalytic activity, detection limit, analytical sensitivity, and stability response.

In-person versus virtual administration of the American College of Radiology gold standard cognitive battery in systemic lupus erythematosus: Are they interchangeable?

OBJECTIVE

During the COVID-19 pandemic, many research studies were adapted, including our longitudinal study examining cognitive impairment (CI) in systemic lupus erythematosus (SLE). Cognitive testing was switched from in-person to virtual. This analysis aimed to determine if the administration method (in-person vs. virtual) of the ACR-neuropsychological battery (ACR-NB) affected participant cognitive performance and classification.

METHODS

Data from our multi-visit, SLE CI study included demographic, clinical, and psychiatric characteristics, and the modified ACR-NB. Three analyses were undertaken for cognitive performance: (1) all visits, (2) non-CI group visits only and (3) intra-individual comparisons. A retrospective preferences questionnaire was given to participants who completed the ACR-NB both in-person and virtually.

RESULTS

We analysed 328 SLE participants who had 801 visits (696 in-person and 105 virtual). Demographic, clinical, and psychiatric characteristics were comparable except for ethnicity, anxiety and disease-related damage. Across all three comparisons, six tests were consistently statistically significantly different. CI classification changed in 11/71 (15%) participants. 45% of participants preferred the virtual administration method and 33% preferred in-person.

CONCLUSIONS

Of the 19 tests in the ACR-NB, we identified one or more problems with eight (42%) tests when moving from in-person to virtual administration. As the use of virtual cognitive testing will likely increase, these issues need to be addressed - potentially by validating a virtual version of the ACR-NB. Until then, caution must be taken when directly comparing virtual to in-person test results. If future studies use a mixed administration approach, this should be accounted for during analysis.

Architecting the High-Entropy Oxides on 2D MXene Nanosheets by Rapid Microwave-Heating Strategy with Robust Photoelectrochemical Oxygen Evolution Performance

High-entropy oxides (HEO) have recently concerned interest as the most promising electrocatalytic materials for oxygen evolution reactions (OER). In this work, a new strategy to the synthesis of HEO nanostructures on Ti₃ C₂ T_x MXene via rapid microwave heating and subsequent calcination at a low temperature is reported. Furthermore, the influence of HEO loading on Ti₃ C₂ T_x MXene is investigated toward OER performance with and without visible-light illumination in an alkaline medium. The obtained HEO/Ti₃ C₂ T_x -0.5 hybrid exhibited an outstanding photoelectrochemical OER ability with a low overpotential of 331 mV at 10 mA cm^-2 and a small Tafel slope of 71 mV dec^-1 , which exceeded that of a commercial IrO₂ catalyst (340 mV at 10 mA cm^-2 ). In particular, the fabricated water electrolyzer with the HEO/Ti₃ C₂ T_x -0.5 hybrid as anode required a less potential of 1.62 V at 10 mA cm^-2 under visible-light illumination. Owing to the strong synergistic interaction between the HEO and Ti₃ C₂ T_x MXene, the HEO/Ti₃ C₂ T_x hybrid has a great electrochemical surface area, many metal active sites, high conductivity, and fast reaction kinetics, resulting in an excellent OER performance. This study offers an efficient strategy for synthesizing HEO-based materials with high OER performance to produce high-value hydrogen fuel.

Correction: Tailoring the MOF structure via ligand optimization afforded a dandelion flower like CoS/Co-Nx/CoNi/NiS catalyst to enhance the ORR/OER in zinc-air batteries

Correction for 'Tailoring the MOF structure via ligand optimization afforded a dandelion flower like CoS/Co-N_x/CoNi/NiS catalyst to enhance the ORR/OER in zinc-air batteries' by Mohan Gopalakrishnan et al., Nanoscale, 2022, 14, 17908-17920, https://doi.org/10.1039/D2NR04933C.

Atomic layer encapsulation of ferrocene into zeolitic imidazolate framework-67 for efficient arsenic removal from aqueous solutions

Arsenic (As(V))-contaminated water is a major global threat to human health and the ecosystem because of its enormous toxicity, carcinogenicity, and high distribution in water streams. Thus, As(V) removal in the environmental samples has received considerable attention. Till now, numerous metal-organic framework materials have been used for the As(V) removal from the aqueous medium, but low As(V) removal and instability of the adsorbents have severely cut off their practical applications. In this study, a ferrocene-encapsulated zeolitic imidazolate framework-67 (Fc-ZIF-67) material was synthesized for As(V) removal from an aqueous solution at neutral pH using a simple solution mixing process. The ferrocene encapsulation provides water-stable and structural defects to ZIF-67. Furthermore, the ferrocene molecule and imidazole linker can enhance As(V) adsorption via both chemisorption and physisorption. The novel Fc-ZIF-67 adsorbent exhibited superior As(V) adsorption performance with an adsorption capacity of 63.29 mg/g at neutral pH. The Langmuir and Freundlich isotherm models were also used to analyze adsorption behavior.

Modulating the Combinatorial Target Power of MgSnN2 via RF Magnetron Sputtering for Enhanced Optoelectronic Performance: Mechanistic Insights from DFT Studies

The unique structural features of many ternary nitride materials with strong chemical bonding and band gaps above 2.0 eV are limited and are experimentally unexplored. It is important to identify candidate materials for optoelectronic devices, particularly for light-emitting diodes (LEDs) and absorbers in tandem photovoltaics. Here, we fabricated MgSnN₂ thin films, as promising II-IV-N₂ semiconductors, on stainless-steel, glass, and silicon substrates via combinatorial radio-frequency magnetron sputtering. The structural defects of the MgSnN₂ films were studied as a function of the Sn power density, while the Mg and Sn atomic ratios remained constant. Polycrystalline orthorhombic MgSnN₂ was grown on the (120) orientation within a wide optical band gap range of ∼2.20-2.17 eV. The carrier densities of 2.18× 10²⁰ to 1.02 × 10²¹ cm^-3, mobilities between 3.75 and 2.24 cm²/Vs, and a decrease in resistivity from 7.64 to 2.73 × 10^-3 Ω cm were confirmed by Hall-effect measurements. These high carrier concentrations suggested that the optical band gap measurements were affected by a Burstein-Moss shift. Furthermore, the electrochemical capacitance properties of the optimal MgSnN₂ film exhibited an areal capacitance of 152.5 mF/cm² at 10 mV/s with high retention stability. The experimental and theoretical results showed that MgSnN₂ films were effective semiconductor nitrides toward the progression of solar absorbers and LEDs.

In situ studies on free-standing synthesis of nanocatalysts via acoustic levitation coupled with pulsed laser irradiation

Acoustic levitation is a distinctive and versatile tool for levitating and processing free-standing single droplets and particles. Liquid droplets suspended in an acoustic standing wave provide container-free environments for understanding chemical reactions by avoiding boundary effects and solid surfaces. We attempted to use this strategy for the production of well-dispersed uniform catalytic nanomaterials in an ultraclean confined area without the addition of external reducing agents or surfactants. In this study, we report on the synthesis of gold and silver nanoparticles (NPs) via acoustic levitation coupled with pulsed laser irradiation (PLI). In situ UV-Visible and Raman spectroscopic techniques were performed to monitor the formation and growth of gold and silver NPs. The PLI was used for the photoreduction of targeted metal ions present in the levitated droplets to generate metal NPs. Additionally, the cavitation effect and bubble movement accelerate the nucleation and decrease the size of NPs. The synthesized Au NPs with ∼ 5 nm size showed excellent catalytic behavior towards the conversion of 4-nitrophenol to 4-aminophenol. This study may open a new door for synthesizing various functional nanocatalysts and for achieving new chemical reactions in suspended droplets.

Construction of direct FeMoO4/g-C3N4-2D/2D Z-scheme heterojunction with enhanced photocatalytic treatment of textile wastewater to eliminate the toxic effect in marine environment

A novel FeMoO₄/g-C₃N₄-2D/2D Z-scheme heterojunction photocatalyst was prepared via wet chemical method. The observed structural morphology of FeMoO₄/g-C₃N₄ reveals the 2D-iron molybdate (FeMoO₄) nanoplates compiled with the 2D-graphitic carbon nitride (g-C₃N₄) nanosheets like structure. The photocatalytic activity of the g-C₃N₄, FeMoO₄, and FeMoO₄/g-C₃N₄ composites were studied via the degradation of Rhodamine B (RhB) as targeted textile dye under visible light irradiation (VLI). The optimal FeMoO₄/g-C₃N₄ (1:3 ratio of g-C₃N₄ and FeMoO₄) composite show an enhanced degradation performance with rate constant value of 0.02226 min^-1 and good stability even after three cycles. Thus, the h+ and O₂^•－are the key radicals in the degradation of RhB under VLI. It is proposed that the FeMoO₄/g-C₃N₄ Z-scheme heterojunction effectively enhances the transfer and separation ability of e^-/h⁺ pairs, by the way increasing the photocatalytic efficiency towards the RhB degradation. Thus, the newly constructed Z-scheme FeMoO₄/g-C₃N₄ heterojunction photocatalyst is a promising material for the remediation of wastewater relevant to elimination of toxic effect in marine environment.

Tailoring the MOF structure via ligand optimization afforded a dandelion flower like CoS/Co-Nx/CoNi/NiS catalyst to enhance the ORR/OER in zinc-air batteries

Due to their affordability and good catalytic activity for oxygen reactions, MOF-derived carbon composites containing metal alloys have piqued interest. However, during synthesis, MOFs have the disadvantage of causing significant carbon evaporation, resulting in a reduction of active sites and durability. This study proposes tailoring the molecular structure of MOFs by optimizing bipyridine and flexible 4-aminodiacetic terephthalic acid ligands, which have numerous coordination modes and framework structures, resulting in fascinating architectures. MOF frameworks having optimized N and O units are coordinated with Co and Ni ions to provide MOF precursors that are annealed at 700 °C in argon. The MOF-derived Co₉S₈/Co-N_x/CoNi/Ni₃S₂@CNS-4 catalyst exhibits excellent catalytic activity, revealing an ORR half-wave potential of 0.86 V and an overpotential (OER) of 196 mV at 10 mA cm^-2, a potential gap of 0.72 V and a Tafel slope of 79 mV dec^-1. The proposed strategy allows for the rational design of N-coordinated Co and CoNi alloys attached to ultrathin N, S co-doped graphitic carbon sheets to enhance bifunctional activity and sufficient active sites. Consequently, the zinc-air battery using the synthesized catalyst shows a high peak power density of 206.9 mW cm^-2 (Pt/C + RuO₂ 116.1 mW cm^-2), a small polarization voltage of 0.96 V after 370 h at 10 mA cm^-2, and an outstanding durability of over 2400 cycles (400 h). The key contributions to the superior performance are the synergetic effects of the CoNi alloys plus the N,S-incorporated carbon skeleton, due to the small charge transfer resistances and enhanced active sites of CoNi, metal-S, and pyridinic N.

Sustainable removal of nitrite waste to value-added ammonia on Cu@Cu2O core-shell nanostructures by pulsed laser technique

The biochemical reduction of nitrite (NO₂^-) ions to ammonia (NH₃) requires six electrons and is catalyzed by the cytochrome c NO₂^- reductase enzyme. This biological reaction inspired scientists to explore the reduction of nitrogen oxyanions, such as nitrate (NO₃^-) and NO₂^- in wastewater, to produce the more valuable NH₃ product. It is widely known that copper (Cu)-based nanoparticles (NPs) are selective for the NO₃^- reduction reaction (NO₃^-RR), but the NO₂^-RR has not been well explored. Therefore, we attempted to address the electrocatalytic conversion of NO₂^- to NH₃ using Cu@Cu₂O core-shell NPs to simultaneously treat wastewater by removing NO₂^- and producing valuable NH₃. The Cu@Cu₂O core-shell NPs were constructed using the pulsed laser ablation of Cu sheet metal in water. The core-shell nanostructure of these particles was confirmed by various characterization techniques. Subsequently, the removal of NO₂^- and the ammonium (NH₄⁺)-N yield rate were estimated using the Griess and indophenol blue methods, respectively. Impressively, the Cu@Cu₂O core-shell NPs exhibited outstanding NO₂^-RR activity, demonstrating a maximum NO₂^- removal efficiency of approximately 94% and a high NH₄⁺-N yield rate of approximately 0.03 mmol h^-1.cm^-2 at -1.6 V vs. a silver/silver chloride reference electrode under optimal conditions. The proposed NO₂^-RR mechanism revealed that the (111) facet of Cu favors the selective conversion of NO₂^- to NH₃ via a six-electron transfer. This investigation may offer a new insight for the rational design and detailed mechanistic understanding of electrocatalyst architecture for the effective conversion of NO₂^- to NH₄⁺.

Architecture of visible-light induced Z-scheme MoS2/g-C3N4/ZnO ternary photocatalysts for malachite green dye degradation

The synthesis of bilayer heterojunctions has received considerable attention recently. Fabrication of novel bilayer composites is of significant interest to improve their photocatalytic efficiency. In this study, molybdenum disulfide (MoS₂), a layered dichalcogenide material exhibiting unique properties, in combination with graphitic carbon nitride (g-C₃N₄), a carbon-based layered material, was fabricated with small amounts of zinc oxide (ZnO). Three composites, MoS₂/g-C₃N₄, MoS₂/ZnO, and MoS₂/g-C₃N₄/ZnO were prepared via a simple exfoliation method and characterized by various physicochemical methods. The Z-scheme charge transfer mechanism in the prepared ternary composite improves efficiency by inhibiting the recombination rate of electron-hole pairs. It has shown excellent performance in degrading a major water contaminant, malachite green (MG) dye, under visible light irradiation.

Unraveling the Synergy of Anion Modulation on Co Electrocatalysts by Pulsed Laser for Water Splitting: Intermediate Capturing by In Situ/Operando Raman Studies

Herein, the authors produce Co-based (Co₃ (PO₄ )₂ , Co₃ O₄ , and Co₉ S₈ ) electrocatalysts via pulsed laser ablation in liquid (PLAL) to explore the synergy of anion modulation on phase-selective active sites in the electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Co₃ (PO₄ )₂ displays an ultralow overpotential of 230 mV at 10 mA cm^-2 with 48.5 mV dec^-1 Tafel slope that outperforms the state-of-the-art Ir/C in OER due to its high intrinsic activity. Meanwhile, Co₉ S₈ exhibits the highest HER performance known to the authors among the synthesized Co-based catalysts, showing the lowest overpotential of 361 mV at 10 mA cm^-2 with 95.8 mV dec^-1 Tafel slope in the alkaline medium and producing H₂ gas with ≈500 mmol g^-1 h^-1 yield rate under -0.45 V versus RHE. The identified surface reactive intermediates over in situ electrochemical-Raman spectroscopy reveal that cobalt(hydr)oxides with higher oxidation states of Co-cation forming under oxidizing potentials on the electrode-electrolyte surface of Co₃ (PO₄ )₂ facilitate the OER, while Co(OH)₂ facilitate the HER. Notably, the fabricated two-electrode electrolyzers using Co₃ (PO₄ )₂ , Co₃ O₄ , and Co₉ S₈ electrocatalysts deliver the cell potentials ≈2.01, 2.11, and 1.89 V, respectively, at 10 mA cm^-2 . This work not only shows PLAL-synthesized electrocatalysts as promising candidates for water splitting, but also provides an underlying principle for advanced energy-conversion catalysts and beyond.

Unveiling the effect of gas treatment on the electronic structure of carbon nanotube-supported Pd catalysts for electroreduction of H2O2 and Heck reaction

This study explored the impact of gas treatments on the structures of multi-walled carbon nanotubes supported Pd (CNT-Pd) catalysts used for electrocatalytic H₂O₂ reduction and the Heck cross-coupling reaction. The CNT-Pd catalyst was prepared by anchoring Pd nanoparticles on thiolated CNTs. XPS was conducted to examine the surface composition and electronic structure changes of the CNT-Pd catalyst before and after gas treatment. The XPS results revealed that as-prepared CNT-Pd contains at least two different oxidation states on the surface, whereon their proportions depend on the gas used for treatment. Treatment with H₂ leads to Pd(0) enrichment near the surface, while O₂ treatment causes Pd(Ⅱ) enrichment of CNT-Pd. All catalysts containing both Pd(0) and Pd(Ⅱ) were active toward H₂O₂ reduction, and the Heck cross-coupling reaction of n-butyl acrylate and 4-iodotoluene; increased proportion of metallic Pd(0) boosted the catalytic reaction. However, the catalyst stability increased as the amount of Pd(II) increased.

Fundamentals and comprehensive insights on pulsed laser synthesis of advanced materials for diverse photo- and electrocatalytic applications

The global energy crisis is increasing the demand for innovative materials with high purity and functionality for the development of clean energy production and storage. The development of novel photo- and electrocatalysts significantly depends on synthetic techniques that facilitate the production of tailored advanced nanomaterials. The emerging use of pulsed laser in liquid synthesis has attracted immense interest as an effective synthetic technology with several advantages over conventional chemical and physical synthetic routes, including the fine-tuning of size, composition, surface, and crystalline structures, and defect densities and is associated with the catalytic, electronic, thermal, optical, and mechanical properties of the produced nanomaterials. Herein, we present an overview of the fundamental understanding and importance of the pulsed laser process, namely various roles and mechanisms involved in the production of various types of nanomaterials, such as metal nanoparticles, oxides, non-oxides, and carbon-based materials. We mainly cover the advancement of photo- and electrocatalytic nanomaterials via pulsed laser-assisted technologies with detailed mechanistic insights and structural optimization along with effective catalytic performances in various energy and environmental remediation processes. Finally, the future directions and challenges of pulsed laser techniques are briefly underlined. This review can exert practical guidance for the future design and fabrication of innovative pulsed laser-induced nanomaterials with fascinating properties for advanced catalysis applications.

Fabrication of Ru-CoFe2O4/RGO hierarchical nanostructures for high-performance photoelectrodes to reduce hazards Cr(VI) into Cr(III) coupled with anodic oxidation of phenols

Dual-functional photo (electro)catalysis (PEC) is a key strategy for removing coexisting heavy metals and phenolic compounds from wastewater treatment systems. To design a PEC cell, it is crucial to use chemically stable and cost-effective bifunctional photocatalysts. The present study shows that ruthenium metallic nanoparticles decorated with CoFe₂O₄/RGO (Ru-CoFe₂O₄/RGO) are effective bifunctional photoelectrodes for the reduction of Cr(VI) ions. Ru-CoFe₂O₄/RGO achieves a maximum Cr(VI) reduction rate of 99% at 30 min under visible light irradiation, which is much higher than previously reported catalysts. Moreover, PEC Cr(VI) reduction rate is also tuned by adding varying concentration of phenol. A mechanism for the concurrent removal of Cr(VI) and phenol has been revealed over a bifunctional Ru-CoFe₂O₄/RGO catalyst. A number of key conclusions emerged from this study, demonstrating the dual role of phenol during Cr(VI) reduction by PEC. Anodic oxidation of phenol produces the enormous H⁺ ion, which appears to be a key component of Cr(VI) reduction. Additionally, phenolic molecules serve as hole (h⁺) scavengers that reduce e^-/h⁺ recombination, thus enhancing the reduction rate of Cr(VI). Therefore, the Ru-CoFe₂O₄/RGO photoelectrode exhibits a promising capability of reducing both heavy metals and phenolic compounds simultaneously in wastewater.

Infrared spectroscopy of ions and ionic clusters upon ionization of ethane in helium droplets

Helium droplets are unique hosts for isolating diverse molecular ions for infrared spectroscopic experiments. Recently, it was found that electron impact ionization of ethylene clusters embedded in helium droplets produces diverse carbocations containing three and four carbon atoms, indicating effective ion–molecule reactions. In this work, similar experiments are reported but with the saturated hydrocarbon precursor of ethane. In distinction to ethylene, no characteristic bands of larger covalently bound carbocations were found, indicating inefficient ion–molecule reactions. Instead, the ionization in helium droplets leads to formation of weaker bound dimers, such as (C2H6)(C2H4)+, (C2H6)(C2H5)+, and (C2H6)(C2H6)+, as well as larger clusters containing several ethane molecules attached to C2H4+, C2H5+, and C2H6+ ionic cores. The spectra of larger clusters resemble those for neutral, neat ethane clusters. This work shows the utility of the helium droplets to study small ionic clusters at ultra-low temperatures.

Fabrication of nonenzymatic electrochemical sensor based on Zn@ZnO core-shell structures obtained via pulsed laser ablation for selective determination of hydroquinone

Herein, we fabricated a more sensitive nonenzymatic electrochemical sensor for the selective determination of hydroquinone as a targeted pollutant at zinc@zinc oxide (Zn@ZnO) core-shell nanostructures. The nanostructured Zn@ZnO materials were produced using pulsed laser ablation in an aqueous medium without the use of any reducing agents or surfactants. The detailed structural, morphological, elemental composition, and electrochemical voltammetric analyses revealed a significant improvement in Zn@ZnO performance for selective hydroquinone detection. A broad linear calibration response was obtained as 10-90 μM with high sensitivity of 0.5673 μA μM^-1 cm^-2 and the low detection limit was 0.10443 μM for detection of hydroquinone. The modified Zn@ZnO electrode's excellent electrochemical sensing performance was attributed to the accessibility of a high electrochemically active surface area (EASA = 0.00345 μF/cm²) and an improved electron transfer rate. Stability and antiinterference tests were also carried out. A 100 fold increase in the concentration of common cations and anions (Na⁺, Mg²⁺, Cl^-, SO₄^2-, and NO₃^-) did not affect the selective determination of HQ. As a result, the fabricated electrochemical sensor has a wide range of potential applications in environmental and biomedical science.

Improved visible light photocatalytic degradation of yttrium doped NiMgAl layered triple hydroxides for the effective removal of methylene blue dye

Fabrication of layered triple hydroxides (LTH) is a typical and remarkable approach to produce new functionalities passionately investigated for photocatalytic removal of organic pollutants from industrial wastewater. The hydrothermal method was used to prepare different weight percentages of yttrium (Y) doped NiMgAl LTH. The structural, functional, optical, and morphological properties of the prepared samples were investigated using X-ray diffraction, Fourier transformed-infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, and scanning electron microscopy. The photocatalytic degradation of the different percentages of Y-doped LTH samples were assessed through the photocatalytic degradation of methylene blue dye under the visible light irradiation. When compared to other lower concentrations of Y doping, the photocatalytic degradation efficiency of 1 wt.% Y-doped LTH was higher. Thus, the optimized LTH's improved photocatalytic performance was attributed to increased visible light absorption with low transmission and improved electron-hole separation.

Surface tuned polyethersulfone membrane using an iron oxide functionalized halloysite nanocomposite for enhanced humic acid removal

Nanomodification of ultrafiltration (UF) membranes has been shown to be a simple and efficient technique for the preparation of high-performance membranes. In this work, an iron oxide functionalized halloysite nanoclay (Fe-HNC) nanocomposite was prepared and used as a nanofiller for polyethersulfone (PES) membranes. The effect of Fe-HNC concentration on the filtration performance of the membrane was investigated by varying the nanocomposite dosage (0-0.5 wt %) in the casting dope. Various characterization studies showed that the incorporation of Fe-HNC nanocomposites improved the membrane morphology and enhanced the surface properties, thermal stability, mechanical strength, hydrophilicity, and porosity. The permeability to pure water and filtration of humic acid (HA) were significantly improved by incorporating Fe-HNC into the PES membranes. The membrane with Fe-HNC loading of 0.1 wt % exhibited the highest pure water permeability (174.3 L/(m² h bar)) and removal of HA (90.1 %), which were 1.8 times and 29 % higher, respectively than the pristine PES membrane. Moreover, fouling studies showed the enhanced antifouling ability of the Fe-HNC nanocomposites modified PES membranes, especially against irreversible fouling. Continuous membrane regeneration-based fouling removal studies from HA showed that the PES/0.1 wt % Fe-HNC membrane exhibited a high fouling recovery of 70.4 % with very low reversible and irreversible fouling resistance of 9.61 % and 14.78 %, respectively, compared to the pristine PES membrane (fouling recovery: 40.4 %; reversible fouling: 21.7 %; irreversible fouling: 20.1 %). Overall, the Fe-HNC nanocomposite proved to be an effective nanomodifier for improving the permeability of PES membranes and the antifouling ability to treat HA polluted aqueous streams.

Silane-treated BaTiO3 ceramic powders for multilayer ceramic capacitor with enhanced dielectric properties

Silane/ceramic combination provides the composites with several advantages from the advancements of new ceramic composite materials with good thermal conductivity, high mechanical and dielectric properties have wide significant applications in electrical and electronic industries. In this study, to enhance the dispersibility of dielectric barium titanate (BaTiO₃) ceramic powder and additives for the fabrication of multilayer ceramic capacitors (MLCCs), surface treatment of the precursor of ceramic powder was performed using silane coupling agents. Dielectric ceramic sheets fabricated from ceramic powders that had been surface-treated with different amounts of N-[3-(trimethoxysilyl)propyl]aniline (TMSPA) which increased the surface gloss. In particular, the dielectric properties of the multilayer ceramic sheet fabricated by stacking sheets from the TMSPA-treated ceramic powder sintering at 1200 °C, it was confirmed that the dielectric constant increased from 881 to 2382 and the dielectric loss dropped from 1.96 to 1.34% with utilization of the TMSPA treatment. The physical and dielectric properties of the TMSPA-treated multilayer ceramic sheet were also determined by Fourier-transform infrared spectroscopy, X-ray diffraction, field-emission scanning electron microscopy, glossmetry, and electrochemical impedance analysis. The results revealed that the TMSPA-modified BaTiO₃ surfaces considerably increased the dielectric property of the fabricated nanocomposite.

Method development and mechanistic study on direct pulsed laser irradiation process for highly effective dechlorination of persistent organic pollutants

Chlorine-based compounds are typical persistent organic pollutants (POPs) that are widely generated in industrial production. This paper reports an effective and rapid pulsed laser irradiation technique for the dechlorination of hexachlorobenzene (HCB), a model pollutant, without additional catalysts or supports. The effects of the laser parameters, including the laser wavelength and power, on the dechlorination efficiency, were also investigated. The optimized results showed that a lower laser wavelength of 266 nm with 10 mJ/pulse power exhibited the highest dechlorination efficiency with 95% within 15 min. In addition, the laser beam effect was examined by designing the direct-pulsed laser single and multipath irradiation system. The results showed that improving the laser beam profile resulted in more than 95% dechlorination efficiency within 5 min. Thus, the dechlorination reaction proceeded much faster as the surface area that the laser beam came in contact with increased due to the multipath system than the single pathway. Gas chromatography identified benzene as the final product of HCB with pentachlorobenzene (PCB), tetrachlorobenzene (TeCB), trichlorobenzene (TCB), dichlorobenzene (DCB), and chlorobenzene (CB) as intermediate products. The mechanism of HCB dechlorination was explained by a comparison of theoretical calculations with the experimental results. The present study reports an advanced technique for the complete dechlorination of chlorobenzenes, which holds great application potential in environmental remediation.

Nanogap-tailored Au nanoparticles fabricated by pulsed laser ablation for surface-enhanced Raman scattering

Herein, gold nanoparticles (Au NPs) were synthesized by pulsed laser ablation (PLA) in a mixed-phase solvent of acetonitrile and water. The size of Au NPs and the number of graphitic carbon (GC) layers were controlled by varying the ratio of the solvent mixture. The surface-enhanced Raman scattering (SERS) of the Au NPs was investigated using 10^-3 M 4-aminobenzenethiol and 10^-4 M 4-nitrobenzenethiol as probe molecules. The SERS activity strongly depended on the nanogaps between particles owing to the formation of hot spots. In the present work, the nanogaps were controlled by changing the amount of GC layers. No GC layers were produced in water, resulting low SERS intensity. In contrast, Au NPs prepared in 30 vol% of acetonitrile showed significant SERS enhancement, which was attributed to the optimal size of the GC-coated NPs and a reasonable gap between them. The obtained results revealed that Au NPs produced by PLA in liquid could be applied in SERS-based microsensors.

Effects of particle size and polymorph type of TiO2 on the properties of BaTiO3 nanopowder prepared by solid-state reaction

Barium titanate (BaTiO₃) has attracted considerable attention as a perovskite ferroelectric ceramic material for electronic multilayer ceramic capacitors (MLCCs). Fine BaTiO₃ nanopowders with a considerably high tetragonality directly influence the typical properties of nanopowders; however, their synthesis has remained challenging. In this study, we analyzed the effect of two different TiO₂ powders with anatase and rutile phases in a solid-state reaction with barium carbonate (BaCO₃). The effect of the particle size ratio (TiO₂/BaCO₃) of the raw materials on the tetragonality and particle size of the as-synthesized BaTiO₃ powders was also determined through extensive characterization of the powders by X-ray diffraction, field-emission scanning electron microscopy, and Raman spectroscopy. The present investigation reveals that the design BaTiO₃ structure is expected to advance the development of efficient catalytic and sensor materials for sustainable environmental applications.

In-situ thermal phase transition and structural investigation of ferroelectric tetragonal barium titanate nanopowders with pseudo-cubic phase

Optimization and miniaturization of existing electronic devices require the development of advanced nanostructured materials with high phase and structural purity. Over the past decade, barium titanate (BaTiO₃) has attracted considerable attention due to its outstanding ferroelectric and dielectric properties. The present study involved the investigation of the phase transition and structural stability of tetragonal BaTiO₃ nanopowders with pseudo-cubic phase using an in-situ high resolution and high temperature X-ray diffraction method. Under ambient conditions, the coexistence the tetragonal and cubic phases with weight fractions of 75.7% and 24.3%, respectively, was determined in BaTiO₃. In the temperature range of 25 °C-300 °C, phase boundaries of BaTiO₃ (180 nm in size) exhibiting several phases were detected. The phase transformation behavior, relative crystal phase content, lattice parameters, crystallite size, and tetragonality of the BaTiO₃ nanopowders were established by the Rietveld refinement method at the onset temperature from 25 °C to 300 °C. Up to 150 °C, the nanopowders exhibited a complete transition of the cubic phase. Additionally, a complete tetragonal to cubic transformation was accomplished by a decrease of tetragonality at 125 °C and an increase in the crystallite size at 300 °C.

Fabrication strategies and surface tuning of hierarchical gold nanostructures for electrochemical detection and removal of toxic pollutants

The intensive research on the synthesis and characterization of gold (Au) nanostructures has been extensively documented over the last decades. These investigations allow the researchers to understand the relationships between the intrinsic properties of Au nanostructures such as particle size, shape, morphology, and composition to synthesize the Au nano/hybrid nanostructures with novel physicochemical properties. By tuning the properties above, these nanostructures are extensively employed to detect and remove trace amounts of toxic pollutants from the environment. This review attempts to document the achievements and current progress in Au-based nanostructures, general synthetic and fabrication strategies and their utilization in electrochemical sensing and environmental remediation applications. Additionally, the applications of Au nanostructures (e.g., as adsorbents, sensing platforms, catalysts, and electrodes) and advancements in the field of electrochemical sensing of different target analytes (e.g., proteins, nucleic acids, heavy metals, small molecules, and antigens) are summarized. The literature survey concludes the existing methods for the detection of toxic contaminants at various concentration levels. Finally, the existing challenges and future research directions on electrochemical sensing and degradation of toxic contaminants using Au nanostructures are defined.

Lignin-mediated green synthesis of functionalized gold nanoparticles via pulsed laser technique for selective colorimetric detection of lead ions in aqueous media

A versatile green synthesis technique of pulsed laser irradiation and the sonochemical process was used for the production of functionalized gold nanoparticles (Au NPs) in the presence of lignin matrixes. In this study, the futuristic advantages of the lignin biopolymer were explored for the preparation of zero-valent Au NPs in the absence of any other reducing agents. The resulting lignin functionalized Au NPs (L-Au_f NPs) were characterized via high-resolution transmission electron microscopy, X-ray diffraction, UV-vis spectroscopy, and Fourier-transform infrared spectroscopy. The optimum lignin concentration can generate uniformly dispersed crystalline L-Au_f NPs. The optimized L-Au_f (1-5) NPs permit the selective colorimetric detection of heavy metal ions; thus, the L-Au_f (1-5) NPs demonstrated a highly selective colorimetric sensing tendency toward Pb²⁺ ions within a short time interval among the various metal ions (Pb²⁺, Fe³⁺, Cu²⁺, Cr⁶⁺, Co²⁺, Ag²⁺, Ca²⁺, Cd²⁺, Ba²⁺, and Hg²⁺). The prominent color change of L-Au_f NPs from red wine to purple indicates the detection of Pb²⁺ ions. This robust characteristic nature of L-Au_f (1-5) NPs can also detect very low concentrations of 1.8 μM in the linear range of 0.1-1 mM. Hence, the outcome of this study coincides with existing studies and indicates that L-Au_f (1-5) NPs can also be used as effective sensors for the rapid and selective detection of Pb²⁺ ions via the colorimetric analysis using the real environmental samples.

Rapid and highly selective electrochemical sensor based on ZnS/Au-decorated f-multi-walled carbon nanotube nanocomposites produced via pulsed laser technique for detection of toxic nitro compounds

Novel ZnS/Au/f-multi-walled carbon nanotube (MWCNT) nanostructures were produced via a pulsed laser-assisted technique followed by a wet chemical process. ZnS nanospheres were synthesized via pulsed laser ablation of a Zn target in DMSO, which was used as a solvent and sulfur source. Notably, no additional sulfur sources, surfactants, or reducing agents were used during the synthesis. The structure and morphology of the prepared materials were characterized by X-ray diffraction, micro-Raman spectroscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The fabricated electrochemical sensor based on ZnS/Au/f-MWCNT nanocomposites exhibited rapid and highly selective detection of a toxic pollutant, namely 4-nitrophenol (4-NP). Linear sweep voltammetry analysis revealed that the optimized ZnS/Au10/f-MWCNT3 nanocomposite displayed a wide linear dynamic response (10-150 μM) with high sensitivity (0.8084μAμM^-1cm^-2) and low limit of detection (30 nM). The excellent 4-NP sensing performance of the modified electrode was attributed to the availability of numerous active sites (electrochemical surface area=0.00369μFcm^-2) and an enhanced electron transfer rate. Interference and stability studies were also conducted. A 100-fold excess of competing ions (Na⁺, K⁺, Mg²⁺, Cl^-, NO₃^-, 4-AP, AA, and 2-NP) did not interfere with the selective detection of 4-NP. The newly fabricated ZnS/Au10/f-MWCNT3 nanocomposite could be an effective sensor for the selective and sensitive detection of toxic organic nitro compounds.

Synthesis of TiO2/RGO with plasmonic Ag nanoparticles for highly efficient photoelectrocatalytic reduction of CO2 to methanol toward the removal of an organic pollutant from the atmosphere

The synergistic photoelectrochemical (PEC) technology is a robust process for the conversion of CO₂ into fuels. However, designing a highly efficient UV-visible driven photoelectrocatalyst is still challenging. Herein, a plasmonic Ag NPs modified TiO₂/RGO photoelectrocatalyst (Ag-TiO₂/RGO) has been designed for the PEC CO₂ reduction into selective production of CH₃OH. HR-TEM analysis revealed that Ag and TiO₂ NPs with average sizes of 4 and 7 nm, respectively, were densely grown on the few-micron-sized 2D RGO nanosheets. The physicochemical analysis was used to determine the optical and textural properties of the Ag-TiO₂/RGO nanohybrids. Under VU-Vis light illumination, Ag-TiO₂/RGO photocathode possessed a current density of 23.5 mA cm^-2 and a lower electrode resistance value of 125 Ω in CO₂-saturated 1.0 M KOH-aqueous electrolyte solution. Catalytic studies showed that the Ag-TiO₂/RGO photocathode possessed a remarkable PEC CO₂ reduction activity and selective production of CH₃OH with a yield of 85 μmol L^-1 cm^-2, the quantum efficiency of 20% and Faradic efficiency of 60.5% at onset potential of -0.7 V. A plausible PEC CO₂ reduction mechanism over Ag-TiO₂/RGO photocathode is schematically demonstrated. The present work gives a new avenue to develop high-performance and stable photoelectrocatalyst for PEC CO₂ reduction towards sustainable liquid fuels production.

Pulsed laser-assisted synthesis of metal and nonmetal-codoped ZnO for efficient photocatalytic degradation of Rhodamine B under solar light irradiation

Solar light-active silver nanoparticle (Ag NP) and nonmetal nitrogen (N)-codoped zinc oxide (ZnO:N/Ag) nanocomposites were fabricated by a pulsed laser-assisted method. N was considered as a promising candidate for tailoring the bandgap of ZnO due to the similar atomic radius as well as lower ionization energy and electronegativity compared to oxygen, which resulted in the formation of a shallow acceptor level in ZnO. Moreover, Ag NPs could enhance the optical properties of the ZnO materials as a consequence of the surface plasmon resonance (SPR) effect. The synthesized ZnO:N/Ag composite materials were characterized by X-ray diffraction (XRD), micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDS), UV-vis diffuse reflectance spectroscopy (UV-DRS), and photoluminescence (PL) analysis. The photocatalytic activity of the ZnO:N/Ag materials was evaluated for the efficient degradation of Rhodamine B (Rh.B) under solar light irradiation. The optimized ZnO:N/Ag-2 nanocomposite exhibited six times higher Rh·B degradation rate than pure ZnO. This was attributed to the enhanced absorption behavior in the solar region as well as the formation of the Schottky junction between ZnO:N and Ag NPs, which resulted in effective charge separation. In addition, the scavenger study revealed that ^•O₂^- radicals facilitated the degradation of Rh.B. The reusability test of the ZnO:N/Ag nanocomposite confirmed high photostability and efficiency of the material in each successive cycle. The present investigation illustrates a rational design of metal and nonmetal-codoped ZnO nanostructures employing a pulsed laser-assisted technique for effective application in photocatalytic remediation of wastewater.

Application of advanced materials in sonophotocatalytic processes for the remediation of environmental pollutants

Significant advances in various industrial processes have resulted in the discharge of toxic pollutants into the environment. Consequently, it is essential to develop efficient wastewater treatment processes to reduce water contamination and increase recycling/reuse. Photocatalytic degradation is considered as an efficient method for the degradation of toxic pollutants in industrial wastewater. However, the use of photocatalytic approaches is associated with numerous limitations, such as lengthy procedures and the necessity for large amounts of catalysts. Hence, it has been proposed that photocatalysis could be combined with other techniques, including sonolysis, electrochemical, photothermal, microwave, ultrafiltration, and biological reactor. The integration of photocatalysis with sonolysis could be remarkably beneficial for environmental remediation. The combination of these processes has the advantages of using uniformly dispersed catalysts, regeneration of the catalyst surface, improved mass transfer, enhanced surface area due to smaller catalyst particles, and production of more active radicals for the degradation of organic pollutants. In this review, an overview on employing sonophotocatalysis for the removal of toxic organic contaminants from aqueous environments is provided. Additionally, the limitations of photocatalysis alone and the fundamental sonophotocatalytic mechanistic pathways are discussed. The importance of utilizing advanced two-dimensional (2D) semiconductor materials in sonophotocatalysis and the common synthetic approaches for the preparation of 2D materials are also highlighted. Lastly, the review provides comprehensive insights into different materials based on metal oxides, chalcogenides, graphene, and metal organic frameworks (MOFs), which are involved in sonophotocatalytic processes employed for the remediation of environmental pollutants.

Solvent-mediated synthesis of BiOI with a tunable surface structure for effective visible light active photocatalytic removal of Cr(VI) from wastewater

The present study investigated the effect of various solvents on the tunable surface morphology and photocatalytic activity (PCA) of bismuth oxyiodide (BiOI), which could be used for the reduction of Cr(VI) under visible light irradiation (VLI). BiOI samples exhibiting different morphologies, i.e., two-dimensional square-like nanosheet and three-dimensional hierarchical flower-like morphology, were synthesized by a hydro/solvothermal process using different solvents, namely H₂O, MeOH, EtOH, and ethylene glycol (EG). The crystal structure, surface morphology, surface area, light-absorption capability, and recombination rate of the photogenerated charge carriers were examined by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller analysis, UV-vis diffuse reflectance spectroscopy, photoluminescence, and transient photocurrent analyses, respectively. The BiOI sample fabricated in EG showed excellent photocatalytic efficiency (~99%) for the reduction of Cr(VI) after 90 min under VLI. The enhanced PCA demonstrated that the high surface area and well-structured surface characteristics of flower-like 3D BiOI microspheres played important roles in the photoreduction process. Moreover, a plausible mechanism for the reduction of Cr(VI) over the EG-BiOI photocatalyst was proposed. The results of the PCA evaluation and recycle test revealed that 3D EG-BiOI microspheres could serve as promising materials for the efficient removal of Cr(VI) from wastewater. Additionally, EG-BiOI could be utilized in other environmental remediation processes.

Crystal structure of 2,6-bis(2-(pyridin-3-yl)ethyl)pyrrolo[3,4-f]isoindole-1,3,5,7(2H,6H)-tetraone, C24H18N4O4

C24H18N4O4, monoclinic, P21/c (no. 14), a = 16.5930(5) Å, b = 5.7298(2) Å, c = 20.8714(6) Å, β = 99.8620(10)°, V = 1955.02(11) Å3, Z = 4, R gt (F) = 0.0415, wR ref (F 2) = 0.1115, T = 193 K.

Production of copper nanoparticles exhibiting various morphologies via pulsed laser ablation in different solvents and their catalytic activity for reduction of toxic nitroaromatic compounds

Comparative experiments were conducted to determine the effects of various solvents (i.e., deionized water, methanol, ethanol, 1-propanol, butanol, ethylene glycol, hexane, and acetonitrile) on the final compositions, morphologies, and catalytic activities of copper-based nanoparticles (NPs). The NPs were effectively synthesized by pulsed laser ablation (PLA) using a copper plate as the target. The obtained copper NPs were characterized utilizing various analytical techniques. It was established that the developed methodology allows for the production of NPs with different morphologies and compositions in a safe and simple manner. When laser ablation of a solid copper plate was performed in acetonitrile, the formation of copper(I) cyanide cubes was observed. On the other hand, in deionized water and methanol, spherical and rod-like particles of copper(I) and copper(II) oxide were detected, respectively. The catalytic activity of the prepared copper NPs in the reduction of aromatic nitro compounds, such as 4-nitrophenol and nitrobenzene, was also evaluated. A high k value was determined for the reduction over the copper(II) oxide NPs produced in methanol. Moreover, particles with graphitic carbon (GC) layers exhibited superior catalytic performance in the reduction of a hydrophobic substance, i.e., nitrobenzene, over the reduction of 4-nitrophenol. The enhanced catalytic activity of this catalyst may be due its unique surface morphology and the synergistic effects between the copper nanostructure and the GC layer. Lastly, a detailed reduction pathway mechanism for the catalytic reduction of 4-nitrophenol and nitrobenzene has been proposed.

Surface functionalized highly porous date seed derived activated carbon and MoS2 nanocomposites for hydrogenation of CO2 into formic acid

In recent years, substantial progress has been made towards developing effective catalysts for the hydrogenation of CO₂ into fuels. However, the quest for a robust catalyst with high activity and stability still remains challenging. In this study, we present a cost-effective catalyst composed of MoS₂ nanosheets and functionalized porous date seed-derived activated carbon (f-DSAC) for hydrogenation of CO₂ into formic acid (FA). As-fabricated MoS₂/f-DSAC catalysts were characterized by FE-SEM, XRD, Raman, FT-IR, BET, and CO₂-TPD analyses. At first, bicarbonate (HCO₃^-) was successfully converted into FA with a high yield of 88% at 200 °C for 180 min under 10 bar H₂ atmosphere. A possible reaction pathway for the conversion of HCO₃^- into FA is postulated. The catalyst has demonstrated high activity and long-term stability over five consecutive cycles. Additionally, MoS₂/f-DSAC catalyst was effectively used for the conversion of gaseous CO₂ into FA at 200 °C under 20 bar (CO₂/H₂ = 1:1) over 15 h. The catalyst exhibited a remarkable TOF of 510 h^-1 with very low activation energy of 12 kJ mol^-1, thus enhancing the catalytic conversion rate of CO₂ into FA. Thus, this work demonstrates the MoS₂/f-DSAC nanohybrid system as an efficient non-noble catalyst for converting CO₂ into fuels.

Anthracene-based fluorescent probe: Synthesis, characterization, aggregation-induced emission, mechanochromism, and sensing of nitroaromatics in aqueous media

The sensitive and selective detection of nitroexplosive molecules thorough a simple methodology has received a significant field of research affecting global security and public safety. In the present study, the synthesis of anthracene-based chalcone (S1) was conducted using a simple condensation method. S1 was found to exhibit unique properties, such as aggregation-induced emission in solution and mechanochromic behavior in solid state. A fluorescent aggregate was applied to sense electron-deficient picric acid (PA) and 2,4-dinitrophenol (2,4-DNP) in an aqueous solution. Notably, the developed test strip-based sensor (S1) could be used to effectively detect PA and 2,4-DNP, which were visualized by the naked eye. Photophysical analysis revealed the occurrence of an electron transfer from electron-rich S1 to the electron-deficient nitro compounds, which was confirmed using density functional theory and ¹H-nuclear magnetic resonance studies. In addition, the observed results confirmed the simple synthesis of S1 as a promising material for the development of test strip-based sensor devices for the detection of toxic and explosive aromatic nitro molecules.

Enhanced photocatalytic activity at multidimensional interface of 1D-Bi2S3@2D-GO/3D-BiOI ternary nanocomposites for tetracycline degradation under visible-light

Structural dimensionality and surface morphology are key properties that greatly affect the functionalities of materials. Herein, we report a synthesis of dimensionally coupled ternary nanocomposites from three-dimensional (3D) bismuth oxyiodide (BiOI), two-dimensional (2D) graphene oxide (GO), and one-dimensional (1D) bismuth sulfide (Bi₂S₃) nanomaterials for tetracycline degradation under visible-light irradiation. The 2%-Bi₂S₃@1%-GO/BiOI ternary nanocomposites show higher degradation efficiency than neat 3D-BiOI. The coupling of neat 1D-Bi₂S₃ with the 1%-GO/BiOI binary nanocomposite does not increase the specific surface area of the resulting 2%-Bi₂S₃@1%-GO/3D-BiOI ternary nanocomposite, but enhances notably its charge carrier separation and migration, according to the analysis of the higher photocurrent, smaller arc radius of the electrochemical impedance spectroscopy and lower photoluminescence intensity. The observed results suggest that the combination of dimensionally coupled composites provides a synergistic effect through an efficient charge transfer process. This work offers new insights into the design and construction of dimensionally coupled ternary nanocomposites for environmental remediation applications.