Continuous synthesis of TiO2-supported noble metal nanoparticles and their application in ammonia borane hydrolysis

Continuous and Scalable Synthesis of Prussian Blue Analogues with Tunable Structure and Composition in Surfactant-Free Microreactor for Stable Zinc-Ion Storage

We represent a segmented flow surfactant-free microfluidic strategy for continuous synthesis of Prussian blue analogues (PBAs) with high dispersity and high crystallization. Representative zinc hexacyanoferrate (ZnHCF) nanocubes were successfully synthesized in a microfluidic reactor within a few minutes via the cooperation method and possessed lower contents of crystal water and Fe(CN)6 3- vacancies than that of synthesis in bulk solution. The nucleation and particle growth process can be precisely controlled by the exploration of different flow rates and reaction temperatures during the formation of ZnHCF nanocubes in segmented flow microfluidic reactors. High crystallinity, low crystal water and vacancies in the ZnHCF structure were presented at relatively high temperatures for the crystal growth process. High-quality ZnHCF with a low content of crystal water showed excellent electrochemical activity and stability towards zinc-ion storage. The continuous and scalable synthesis approach can be extended to the fabrication of other PBAs such as NiHCF, CoHCF, MnHCF, and CuHCF with high dispersity without using any surfactants. The controllable construction of PBAs with tunable properties in microfluidic reactors provides a promising direction to minimize the gap between commercial reality and laboratory research.

Microreactor-based micro/nanomaterials: fabrication, advances, and outlook

Micro/nanomaterials are widely used in optoelectronics, environmental materials, bioimaging, agricultural industries, and drug delivery owing to their marvelous features, such as quantum tunneling, size, surface and boundary, and Coulomb blockade effects. Recently, microreactor technology has opened up broad prospects for green and sustainable chemical synthesis as a powerful tool for process intensification and microscale manipulation. This review focuses on recent progress in the microreactor synthesis of micro/nanomaterials. First, the fabrication and design principles of existing microreactors for producing micro/nanomaterials are summarized and classified. Afterwards, typical examples are shown to demonstrate the fabrication of micro/nanomaterials, including metal nanoparticles, inorganic nonmetallic nanoparticles, organic nanoparticles, Janus particles, and MOFs. Finally, the future research prospects and key issues of microreactor-based micro/nanomaterials are discussed. In short, microreactors provide new ideas and methods for the synthesis of micro/nanomaterials, which have huge potential and inestimable possibilities in large-scale production and scientific research.

Recent Advances and Perspectives on Supported Catalysts for Heterogeneous Hydrogen Production from Ammonia Borane

Ammonia borane (AB), a liquid hydrogen storage material, has attracted increasing attention for hydrogen utilization because of its high hydrogen content. However, the slow kinetics of AB hydrolysis and the indefinite catalytic mechanism remain significant problems for its large-scale practical application. Thus, the development of efficient AB hydrolysis catalysts and the determination of their catalytic mechanisms are significant and urgent. A summary of the preparation process and structural characteristics of various supported catalysts is presented in this paper, including graphite, metal-organic frameworks (MOFs), metal oxides, carbon nitride (CN), molybdenum carbide (MoC), carbon nanotubes (CNTs), boron nitride (h-BN), zeolites, carbon dots (CDs), and metal carbide and nitride (MXene). In addition, the relationship between the electronic structure and catalytic performance is discussed to ascertain the actual active sites in the catalytic process. The mechanism of AB hydrolysis catalysis is systematically discussed, and possible catalytic paths are summarized to provide theoretical considerations for the designing of efficient AB hydrolysis catalysts. Furthermore, three methods for stimulating AB from dehydrogenation by-products and the design of possible hydrogen product-regeneration systems are summarized. Finally, the remaining challenges and future research directions for the effective development of AB catalysts are discussed.

Cornstalk biochar-TiO2 composites as alternative photocatalyst for degrading methyl orange

Dye wastewater is one of the most harmful wastewater types generated during industrial processes. Effectively treating dye wastewater is essential. This study used TiO₂ and cornstalk biochar to prepare biochar-TiO₂ composites in order to treat methyl orange (MO) in the water. It is found that composites prepared using biochar generated at 700 ℃ and TiO₂/biochar mass ratio values of 0.75/1 showed the best performance on decolorization efficiency and mineralization efficiency of MO while low pH, low initial MO concentration, and 1 g/L of composite amount added can enhance MO degradation efficiency. Additionally, it is also noted that biochar-TiO₂ composites were easier to separate from water compared to pure TiO₂. This benefits the recycling of biochar-TiO₂ composites after application. Furthermore, the study indicated that the biochar-TiO₂ composites degrade MO by a combination of adsorption and photocatalysis while photoelectron (e^-) and ·O₂^- are the key species participating in photocatalytic degradation of MO. These research outcomes suggest that cornstalk biochar and TiO₂ can be used to prepare composites, which can be seen as an alternative photocatalyst for dye wastewater treatment. However, further investigations related to their long-term applications and in real scale projects are recommended.

Synthesis of rGO supported Cu@FeCo catalyst and catalytic hydrolysis of ammonia borane

Highly dispersed Cu@FeCo/rGO catalysts have been prepared by two-step reduction method and used for hydrogen production from ammonia borane (NH₃BH₃, AB) hydrolysis at 298 K. The activity and reusability of synthesized composite catalyst were much more higher than Cu@FeCo for AB hydrolysis dehydrogenation at 298 K. Kinetic study manifested that AB hydrolysis dehydrogenation with Cu@FeCo/rGO catalysts was approaching to the first order at different catalyst concentrations. The hydrolysis reaction completed within four minutes, and its maximum hydrogen production rate reached to 7863.0 ml min^-1 g^-1 at 298 K.

Excellent Catalytic Performance of ISOBAM Stabilized Co/Fe Colloidal Catalysts toward KBH4 Hydrolysis

Recently, developing a cost-effective and high-performance catalyst is regarded as an urgent priority for hydrogen generation technology. In this work, ISOBAM-104 stabilized Co/Fe colloidal catalysts were prepared via a co-reduction method and used for the hydrogen generation from KBH₄ hydrolysis. The obtained ISOBAM-104 stabilized Co₁₀Fe₉₀ colloidal catalysts exhibit an outstanding catalytic activity of 37,900 mL-H₂ min^-1 g-Co^-1, which is far higher than that of Fe or Co monometallic nanoparticles (MNPs). The apparent activation energy (E_a) of the as-prepared Co₁₀Fe₉₀ colloidal catalysts is only 14.6 ± 0.7 kJ mol^-1, which is much lower than that of previous reported noble metal-based catalysts. The X-ray photoelectron spectroscopy results and density functional theory calculations demonstrate that the electron transfer between Fe and Co atoms is beneficial for the catalytic hydrolysis of KBH₄.

Research progress of photocatalysis for algae killing and inhibition: a review

The healthy development of biodiversity has been threatened frequent water eutrophication. In recent years, photocatalytic technology, which has attracted researchers' attention, not only showed increasing potential in the field of organic pollutant degradation, but also many kinds of photocatalysts were used in the field of red tide pollution control at present, which showed superior ability to inactivate harmful algae and degrade algal toxins. Researches have also explored the mechanisms of photocatalytic algae inhibition. In this study, the current research progress in the field of photocatalytic algae inhibition was systematically discussed from several aspects, such as common types of photocatalysts, modification methods of photocatalysts, types of tested algae for photocatalytic algae inhibition, and action mechanism of inactivated algae cells, so as to provide a certain theoretical basis for further application research of photocatalysts in the field of algae removal in the later period.