Industrial Chemistry & Materials最新文献

Hydrogen holds the advantages of high gravimetric energy density and zero emission. Effective storage and transportation of hydrogen constitute a critical and intermediate link for the advent of widespread applications of hydrogen energy. Magnesium hydride (MgH₂) has been considered as one of the most promising hydrogen storage materials because of its high hydrogen storage capacity, excellent reversibility, sufficient magnesium reserves, and low cost. However, great barriers both in the thermodynamic and the kinetic properties of MgH₂ limit its practical application. Doping catalysts and nanostructuring are two facile but efficient methods to prepare high-performance magnesium (Mg)-based hydrogen storage materials. Core–shell nanostructured Mg-based hydrogen storage materials synergize the strengths of the above two modification methods. This review summarizes the preparation methods and expounds the thermodynamic and kinetic properties, microstructure and phase changes during hydrogen absorption and desorption processes of core–shell nanostructured Mg-based hydrogen storage materials. We also elaborate the mechanistic effects of core–shell nanostructures on the hydrogen storage performance of Mg-based hydrogen storage materials. The goal of this review is to point out the design principles and future research trends of Mg-based hydrogen storage materials for industrial applications.

Keywords: Hydrogen storage; Mg/MgH₂; Core–shell nanostructure; Thermodynamics and kinetics.

At present, the catalysts commercially used for the oxygen reduction reaction of the cathode of proton exchange membrane fuel cells (PEMFCs) are carbon-supported platinum-based catalysts. However, the carbon supports are susceptible to corrosion under harsh working conditions, which greatly shortens the life of the catalysts. Highly stable carbon supports are urgently required for high-performance PEMFCs. In this work, we developed structure-stable and highly graphitized three-dimensional network carbon nanofibers (CNF) derived from polyaniline by heat treatment at 1200 °C. The CNF-1200-based catalyst (PtNi/CNF-1200) loaded with PtNi nanoparticles showed excellent stability. After 5000 cycles from 1.0 to 1.5 V in oxygen saturated 0.1 M HClO₄ electrolyte, the losses in the half-wave potential and mass activity were only 5 mV and 15%, respectively, far lower than those of commercial Pt/C. The high graphitization degree of CNF-1200 promotes the corrosion resistance of the catalyst. In addition, nitrogen doping effectively facilitates the catalyst–support interaction, stabilizes the highly dispersed PtNi nanoparticles, and improves the stability and activity of PtNi/CNF-1200.

Keywords: Support stability; Graphitization degree; Nitrogen doping; Oxygen reduction reaction.

Two-dimensional metal–organic-framework (2D MOF) nanosheets with a modular nature and tunable structures exhibit a bright future for sensors, separation, and catalysis. Developing ultrathin 2D MOF nanosheets with unique physical and chemical properties is urgently required but very challenging. Although the chemical exfoliation strategy has been regarded as a promising way to exfoliate large amounts of three-dimensional (3D) pillar-layered MOFs, this method still faces many problems and remains insufficient. In this study, a novel chemical exfoliation method is developed for the target preparation of 2D MOF monolayers from the 3D pillar-layered MOFs. The Co/Zn/Cu-MOFs with a pillar ligand of trans-1,2-bis(4-pyridyl)ethylene (bipyen) are subjected to be broken by the cleavage of CC bonds in the bipyen ligands via an ozone oxidation reaction. As chemical exfoliation is processed via the oxidation of the pillar ligand by ozone, the thickness of the 2D MOFs can be tuned by the control of oxidation time and the obtained 2D Co/Zn/Cu-MOF monolayers are functionalized with a –COOH group. This study provides an effective and general chemical exfoliation method to prepare monolayer MOFs from the 3D pillar-layered MOFs with bipyen as the pillar ligand.

Keywords: 3D pillar-layered MOFs; Ultrathin 2D MOF monolayers; Top-down strategy; Chemical exfoliation; Ozonolysis–oxidation.

Fluorescence microscopy has evolved from a purely biological tool to a powerful chemical instrument for imaging and kinetics research into nanocatalysis. And the demand for high signal-to-noise ratio and temporal–spatial resolution detection has encouraged rapid growth in total internal reflection fluorescence microscopy (TIRFM). By producing an evanescent wave on the glass–water interface, excitation can be limited to a thin plane to ensure the measured accuracy of kinetics and image contrast of TIRFM. Thus, this unique physical principle of TIRFM makes it suitable for chemical research. This review outlines applications of TIRFM in the field of chemistry, including imaging and kinetics research. Hence, this review could provide guidance for beginners employing TIRFM to solve current challenges creatively in chemistry.

Keywords: Total internal reflection fluorescence microscopy; Nanocatalysis; Imaging; Kinetics analysis.

Driven by the growing need to decarbonize, hydrogen energy is considered a potential alternative to fossil fuels. However, due to the problems associated with energy storage and transportation for portable applications, the scalable utilization of hydrogen is not fully developed. In this perspective, the potential of utilizing ammonia as a hydrogen carrier for on-site power generation via ammonia decomposition is systematically discussed. Firstly, an analysis of the chemical properties of ammonia and the limitations of this product for hydrogen production are presented. Secondly, some existing worldwide industrial projects that present the current development status are summarized. Then, recent advances in target engineering of efficient catalysts via various strategies are provided. Finally, different types of structured reactors to date for ammonia decomposition are explored. This perspective aims to shed light on the potential of ammonia as a promising alternative to traditional hydrogen storage methods and highlights the challenges and opportunities that lie ahead in this exciting field of research.

Keywords: Ammonia decomposition; Hydrogen carrier; On-site generation; Heterogeneous catalysts; Reactor.

Acetalization represents an appealing approach for the valorization of biobased platform molecules into valuable chemicals and fuels. Typically, it serves as both a synthesis tool for renewable cyclic acetals and a protection strategy to improve selectivity in biomass conversion. This contribution provides an overview on the application of the acetalization strategy in biomass valorization including synthesis of cyclic acetal fuel additives from the acetalization of biobased furanic compounds with biogenic ethylene glycol/glycerol and acetalization as a protection approach to improve product selectivity in biomass valorization. The latest progresses in the development of catalytic systems for the acetalization of biobased furanic compounds and biogenic ethylene glycol/glycerol are systematically summarized and discussed, with an emphasis on the reaction pathway, relationship between catalyst structures and their performance, and relevant catalytic mechanism. Moreover, the application of the acetalization strategy for protecting carbonyl groups/diol structure functionalities to improve the target products' selectivity in lignin depolymerization, 5-hydroxymethylfurfural oxidation, sorbitol dehydration, and xylose hydrogenation is also highlighted. Eventually, the prospects and challenges in the synthesis of cyclic acetal fuel additives as well as applying acetalization as a protection strategy in biomass valorization are outlined.

Keywords: Oxygenated fuel additives; Furanic compounds; Bioalcohols; Acetalization; Chemocatalysis.

Sustainable and efficient water treatment techniques to improve the quality of water for various applications include advanced oxidation processes (AOP), mainly focusing on heterogeneous photocatalysis. Materials science and nanotechnology have contributed to tailoring the properties of photocatalytic materials to significantly enhance their photoactivity and stability. Here we report the development of a well-organized nanoporous TiO₂-based photocatalytic reactor for water treatment. Nanoporous TiO₂ materials were directly grown using a two-step electrochemical anodization process in ethylene glycol + 0.3 wt% NH₄F + 2 wt% H₂O. The prepared nanomaterials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDX). To enhance the photocatalytic activity of the system, water scrubbing was incorporated to boost the presence of oxygen in the water, enhancing the electron uptake at the conduction band thus significantly reducing the electron–hole recombination and increasing the photocatalytic activity. To further enhance the efficiency and reduce the negative environmental impact of the technology, a UVA-LED assembly was used instead of the typical mercury-based UV lamps for photocatalysis. The nanoporous TiO₂ was tested as a catalyst for the photochemical oxidation of various categories of pollutants; dye (methylene blue), and the removal of microbes such as E. coli. The photoreactor developed in this research work was also successfully applied and tested in real-world applications such as keeping heavily used hot-tub water clean without using harmful chemicals (chlorine, bromine, ozone, etc.) or expensive equipment. The simplicity and efficacy of the new approach described in this study make possible the integration of nanoporous TiO₂ in the design of high-performance air and water purification technologies.

Keywords: TiO₂ photocatalyst; UVA-LEDs; Nanostructured materials; Photochemical oxidation; Wastewater treatment; Water scrubbing.

Anti-scaling technology for pipelines has always been a focus of oilfield industrial production. Compared with traditional metal pipes, polyethylene (PE) pipes have unique advantages in terms of corrosion resistance, surface friction resistance, and service life. In this paper, aiming at an enhancement of anti-scaling and corrosion-resistant properties, as well as increased mechanical properties, PE nanocomposites have been prepared by the introduction of modified carbon nanotubes (m-CNTs) into the PE matrix. To improve the interface compatibility of the composites, the CNTs were treated with reactive tetrabutyl titanate after nitric acid oxidation, which brings about uniform dispersion of the CNTs and intimate interface interaction. As the m-CNT fraction increases, the PE crystallinity displays a slight increase. Polarized microscopy shows that the scaling on the surface of the composite material is obviously reduced compared with pure PE, because the surface free energy of the composite material decreases. Moreover, due to the good dispersion, the composites show enhanced mechanical properties. That is, by adding 1.10 wt% CNTs, the tensile stress and impact toughness of the composites are 20.76 MPa and 37.89 kJ m⁻², respectively, increases of 15.0% and 11.9% compared with pure PE. This paper supports the idea that the crystallinity of the PE matrix can be improved by adding CNTs, thereby increasing the corrosion resistance and anti-scaling properties. This work can provide inspiration for using the methods of scale inhibition and corrosion resistance in polymer nanocomposites.

Keywords: Carbon nanotube; Nanocomposite; Polyethylene; Anti-scaling; Corrosion-resistant.

Correction for ‘Lithium-mediated electrochemical dinitrogen reduction reaction’ by Muhammad Saqlain Iqbal et al., Ind. Chem. Mater., 2023, DOI: https://doi.org/10.1039/D3IM00006K.