Complex oxide-noble metal conjugated nanoparticles

A Review on Pulsed Laser Fabrication of Nanomaterials in Liquids for (Photo)catalytic Degradation of Organic Pollutants in the Water System

The water pollution caused by the release of organic pollutants has attracted remarkable attention, and solutions for wastewater treatment are being developed. In particular, the photocatalytic removal of organic pollutants in water systems is a promising strategy to realize the self-cleaning of ecosystems under solar light irradiation. However, at present the semiconductor-based nanocatalysts can barely satisfy the industrial requirements because their wide bandgaps restrict the effective absorption of solar light, which needs an energy band modification to boost the visible light harvesting via surface engineering. As an innovative approach, pulsed laser heating in liquids has been utilized to fabricate the nanomaterials in catalysis; it demonstrates multi-controllable features, such as size, morphology, crystal structure, and even optical or electrical properties, with which photocatalytic performances can be precisely optimized. In this review, focusing on the powerful heating effect of pulsed laser irradiation in liquids, the functional nanomaterials fabricated by laser technology and their applications in the catalytic degradation of various organic pollutants are summarized. This review not only highlights the innovative works of pulsed laser-prepared nanomaterials for organic pollutant removal in water systems, such as the photocatalytic degradation of organic dyes and the catalytic reduction of toxic nitrophenol and nitrobenzene, it also critically discusses the specific challenges and outlooks of this field, including the weakness of the produced yields and the relevant automatic strategies for massive production.

Review on magnetic spinel ferrite (MFe2O4) nanoparticles: From synthesis to application

Magnetic spinel ferrite materials offer various applications in biomedical, water treatment, and industrial electronic devices, which has sparked a lot of attention. This review focuses on the synthesis, characterization, and applications of spinel ferrites in a variety of fields, particularly spinel ferrites with doping. Spinel ferrites nanoparticles doped with the elements have remarkable electrical and magnetic properties, allowing them to be used in a wide range of applications such as magnetic fields, microwave absorbers, and biomedicine. Furthermore, the physical properties of spinel ferrites can be modified by substituting metallic atoms, resulting in improved performance. The most recent and noteworthy applications of magnetic ferrite nanoparticles are reviewed and discussed in this review. This review goes over the synthesis, doping and applications of different types of metal ferrite nanoparticles, as well as views on how to choose the appropriate magnetic ferrites based on the intended application.

A Review on Pulsed Laser Preparation of Nanocomposites in Liquids and Their Applications in Photocatalysis

The purpose of photocatalysis is to realize the conversion between solar energy and chemical energy, and it is essential to develop a high-performance photocatalyst under visible-light irradiation. The conventional methods for photocatalyst preparation are mainly wet chemical routes, and abundant yields can be obtained. However, the products are not neat and accompanied by chemical groups and impurities, which are not beneficial for the enhancement of photocatalytic performance. In recent years, as a powerful tool for nanomaterial fabrication, pulsed laser heating in a liquid medium has been utilized to prepare a variety of nanocomposites. Products with synergistic effects and high crystallinity can be rapidly prepared under pulsed laser selective heating, which is beneficial for obtaining more effective photocatalytic performance. In this review, the typical characteristics of pulsed laser heating in liquids and their prepared nanocomposites for photocatalytic applications are summarized. This review not only highlights the innovative works of pulsed-laser-prepared nanocomposites in liquids for photocatalysis but also briefly introduces the specific challenges and prospects of this field.

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.

Accelerated Digital Biodetection Using Magneto-plasmonic Nanoparticle-Coupled Photonic Resonator Absorption Microscopy

Rapid, ultrasensitive, and selective quantification of circulating microRNA (miRNA) biomarkers in body fluids is increasingly deployed in early cancer diagnosis, prognosis, and therapy monitoring. While nanoparticle tags enable detection of nucleic acid or protein biomarkers with digital resolution and subfemtomolar detection limits without enzymatic amplification, the response time of these assays is typically dominated by diffusion-limited transport of the analytes or nanotags to the biosensor surface. Here, we present a magnetic activate capture and digital counting (mAC+DC) approach that utilizes magneto-plasmonic nanoparticles (MPNPs) to accelerate single-molecule sensing, demonstrated by miRNA detection via toehold-mediated strand displacement. Spiky Fe₃O₄@Au MPNPs with immobilized target-specific probes are "activated" by binding with miRNA targets, followed by magnetically driven transport through the bulk fluid toward nanoparticle capture probes on a photonic crystal (PC). By spectrally matching the localized surface plasmon resonance of the MPNPs to the PC-guided resonance, each captured MPNP locally quenches the PC reflection efficiency, thus enabling captured MPNPs to be individually visualized with high contrast for counting. We demonstrate quantification of the miR-375 cancer biomarker directly from unprocessed human serum with a 1 min response time, a detection limit of 61.9 aM, a broad dynamic range (100 aM to 10 pM), and a single-base mismatch selectivity. The approach is well-suited for minimally invasive biomarker quantification, enabling potential applications in point-of-care testing with short sample-to-answer time.

Pulsed Laser in Liquids Made Nanomaterials for Catalysis

Catalysis is essential to modern life and has a huge economic impact. The development of new catalysts critically depends on synthetic methods that enable the preparation of tailored nanomaterials. Pulsed laser in liquids synthesis can produce uniform, multicomponent, nonequilibrium nanomaterials with independently and precisely controlled properties, such as size, composition, morphology, defect density, and atomistic structure within the nanoparticle and at its surface. We cover the fundamentals, unique advantages, challenges, and experimental solutions of this powerful technique and review the state-of-the-art of laser-made electrocatalysts for water oxidation, oxygen reduction, hydrogen evolution, nitrogen reduction, carbon dioxide reduction, and organic oxidations, followed by laser-made nanomaterials for light-driven catalytic processes and heterogeneous catalysis of thermochemical processes. We also highlight laser-synthesized nanomaterials for which proposed catalytic applications exist. This review provides a practical guide to how the catalysis community can capitalize on pulsed laser in liquids synthesis to advance catalyst development, by leveraging the synergies of two fields of intensive research.

AgCl-ZnAl Layered Double Hydroxides as Catalysts with Enhanced Photodegradation and Antibacterial Activities

Surface-modified ZnAl layered double hydroxides (LDHs) were prepared by reaction of AgNO3, with both ZnAlCl (LDH1) and ZnAlCO3 exchanged on the surface with chloride anions (LDH3). In this way, AgCl nanoparticles with crystalline domains ranging from 40 to 100 nm were grown on the LDH surface. An additional sample was prepared by partial reduction of silver to obtain Ag@AgCl-LDH (LDH2). The composites were tested as catalysts in Rhodamine B (RhB) degradation, wherein LDH2 showed complete cleavage of RhB after 45 min of irradiation versus 70 min needed in the presence of AgCl. This time decreased to 35 min for LDH1 and 15 min for LDH3, underlining the role of the AgCl dimensions and anion in the interlayer region. Studies on the reactive species involved in the degradation process revealed that, for all catalysts, O2·− was the main active species, while, to some extent, holes contribute to the activity of the LDH3. Finally, the composites showed high bactericidal activity, under irradiation, against Escherichia coli, comparable with that of Gentamicin, the positive control. A synergic effect of silver released from the composites and the production of reactive oxygen species was considered.

Atomic layer deposition with rotary reactor for uniform hetero-junction photocatalyst, g-C3N4@TiO2 core–shell structures

A heterojunction of TiO₂ grown on g-C₃N₄ particles is demonstrated using atomic layer deposition (ALD), equipped with a specifically designed rotary reactor for maintaining stable mechanical dispersion of g-C₃N₄ particles during ALD. The photocatalytic activity of the g-C₃N₄@ALD-TiO₂ core–shell composites was examined using the degradation of rhodamine B dye under visible light irradiation. The optimal composite with 5 ALD cycles of TiO₂ exhibited the highest photocatalytic reaction rate constant among the composites with a range of ALD cycles from 2 to 200 cycles, which was observed to be 3 times higher than that of pristine g-C₃N₄ and 2 times higher than that of g-C₃N₄@TiO₂ composite prepared using a simple impregnation method. The ALD-TiO₂ were well-dispersed on the g-C₃N₄ surface, while TiO₂ nanoparticles were agglomerated onto the g-C₃N₄ in the g-C₃N₄@TiO₂ composite prepared by the impregnation method. This created uniform and stable heterojunctions between the g-C₃N₄ and TiO₂, thus, enhancing the photocatalytic activity.

A heterojunction of TiO₂ grown on g-C₃N₄ particles is demonstrated using atomic layer deposition (ALD), equipped with a specifically designed rotary reactor for maintaining stable mechanical dispersion of g-C₃N₄ particles during ALD.

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

Driven by functionality and purity demand for applications of inorganic nanoparticle colloids in optics, biology, and energy, their surface chemistry has become a topic of intensive research interest. Consequently, ligand-free colloids are ideal reference materials for evaluating the effects of surface adsorbates from the initial state for application-oriented nanointegration purposes. After two decades of development, laser synthesis and processing of colloids (LSPC) has emerged as a convenient and scalable technique for the synthesis of ligand-free nanomaterials in sealed environments. In addition to the high-purity surface of LSPC-generated nanoparticles, other strengths of LSPC include its high throughput, convenience for preparing alloys or series of doped nanomaterials, and its continuous operation mode, suitable for downstream processing. Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials, thereby enabling the fabrication of bioconjugates and heterogeneous catalysts. Accurate size control of LSPC-synthesized materials ranging from quantum dots to submicrometer spheres and recent upscaling advancement toward the multiple-gram scale are helpful for extending the applicability of LSPC-synthesized nanomaterials to various fields. By discussing key reports on both the fundamentals and the applications related to laser ablation, fragmentation, and melting in liquids, this Article presents a timely and critical review of this emerging topic.

Scalable synthesis of cubic Cu1.4S nanoparticles with long-term stability by laser ablation of salt powder

An intensive laser was employed to irradiate a salt target, and the fierce synthetic conditions result in a large amount of Cu_1.4S nanoparticles with exceptional long-term stability.

Enhanced microwave absorption property of reduced graphene oxide (RGO)-MnFe2O4 nanocomposites and polyvinylidene fluoride

MnFe2O4 nanoparticles have been synthesized on a large scale by a simple hydrothermal process in a wild condition, and the RGO/MnFe2O4 nanocomposites were also prepared under ultrasonic treatment based on the synthesized nanoparticles. The absorption properties of MnFe2O4/wax, RGO/MnFe2O4/wax and the RGO/MnFe2O4/PVDF (polyvinylidene fluoride) composites were studied; the results indicated that the RGO/MnFe2O4/PVDF composites show the most excellent wave absorption properties. The minimum reflection loss of RGO/MnFe2O4/PVDF composites with filler content of 5 wt % can reach -29.0 dB at 9.2 GHz, and the bandwidth of frequency less than -10 dB is from 8.00 to 12.88 GHz. The wave absorbing mechanism can be attributed to the dielectric loss, magnetic loss and the synergetic effect between RGO+MnFe2O4, RGO+PVDF and MnFe2O4+PVDF.

Characterization of 3D interconnected microstructural network in mixed ionic and electronic conducting ceramic composites

The microstructure and connectivity of the ionic and electronic conductive phases in composite ceramic membranes are directly related to device performance. Transmission electron microscopy (TEM) including chemical mapping combined with X-ray nanotomography (XNT) have been used to characterize the composition and 3-D microstructure of a MIEC composite model system consisting of a Ce0.8Gd0.2O2 (GDC) oxygen ion conductive phase and a CoFe2O4 (CFO) electronic conductive phase. The microstructural data is discussed, including the composition and distribution of an emergent phase which takes the form of isolated and distinct regions. Performance implications are considered with regards to the design of new material systems which evolve under non-equilibrium operating conditions.