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1. Two-dimensional transition metal carbides as supports for tuning the chemistry of catalytic nanoparticles

   https://doi.org/10.1038/s41467-018-07502-5  

   Li, Zhe; Yu, Liang; Milligan, Cory; Ma, Tao; Zhou, Lin; Cui, Yanran; Qi, Zhiyuan; Libretto, Nicole; Xu, Biao; Luo, Junwei; et al (December 2018, Nature Communications)

   Abstract Supported nanoparticles are broadly employed in industrial catalytic processes, where the active sites can be tuned by metal-support interactions (MSIs). Although it is well accepted that supports can modify the chemistry of metal nanoparticles, systematic utilization of MSIs for achieving desired catalytic performance is still challenging. The developments of supports with appropriate chemical properties and identification of the resulting active sites are the main barriers. Here, we develop two-dimensional transition metal carbides (MXenes) supported platinum as efficient catalysts for light alkane dehydrogenations. Ordered Pt 3 Ti and surface Pt 3 Nb intermetallic compound nanoparticles are formed via reactive metal-support interactions on Pt/Ti 3 C 2 T x and Pt/Nb 2 CT x catalysts, respectively. MXene supports modulate the nature of the active sites, making them highly selective toward C–H activation. Such exploitation of the MSIs makes MXenes promising platforms with versatile chemical reactivity and tunability for facile design of supported intermetallic nanoparticles over a wide range of compositions and structures. 

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2. Controlling morphology in electrosprayed methylcellulose nanowires via nanoparticle addition: coarse-grained modeling and experiments

   https://doi.org/10.1039/D2NR04177D  

   Blisko, Jonathan M.; Grzenda, Michael J.; Vladimirsky, Rachel M.; Shuck, Christopher E.; Singer, Jonathan P.; Yong, Xin (December 2022, Nanoscale)

   Electrospray deposition (ESD) has shown great promise for manufacturing micro- and nanostructured coatings at scale on versatile substrates with complex geometries. ESD exhibits a broad spectrum of morphologies depending upon the properties of spray fluids. Among them are nanowire forests or foams obtained via the in-air gelation of electrospray droplets formed from methylcellulose (MC) solutions. In this study, we explored MC ESD loaded with nanoparticles of various shapes and uncovered the effects of particle fillers on morphology evolution using coarse-grained simulations and physical experiments. Utilizing electrostatic dissipative particle dynamics, we modeled the electrohydrodynamic deformation of particle-laden MC droplets undergoing in-flight evaporation. The simulations quantitatively predict the suppression of droplet deformation as the size or concentration of spherical nanoparticles increases. While small particles can be readily encapsulated into the nanowire body, large particles can arrest nanowire formation. The model was extended to nanoparticles with complex topologies, showing MC nanowires emerging from particle edges and vertices due to curvature-enhanced electric stress. In all cases, strong agreements were found between simulation and experimental results. These results demonstrate the efficacy of the coarse-grained model in predicting the morphology evolution of electrosprayed droplets and lay the groundwork for employing MC nanowires for developing nanostructured composites. 

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3. Effects of oxygen concentration on nanoparticle formation during combustion of iron powders

   https://doi.org/10.1016/j.fuel.2025.135366  

   Chang, Di; Thijs, Leon C; Panahi, Aidin; Mi, Xiaocheng; Bergthorson, Jeffrey M; Levendis, Yiannis A (October 2025, Fuel)

   Egolfopoulos, Fokion (Ed.)

   Powdered iron is being investigated for its potential use as a carbon-free fuel due to its ability to burn heterogeneously and produce oxide particles, which can be collected, reduced back to iron and burned again. However, high temperature oxidation of iron particles can induce partial vaporization/decomposition and evolution of nanometric iron oxide particles. To investigate the formation process of nanoparticles in iron combustion, iron powders (consisting of spheroidal 45–53 μm particles) were injected in an electrically-heated drop tube furnace, operated at a maximum gas temperature of 1375 K, where they experienced high heating rates (104 K/s). The particles reacted with oxygen at concentrations of 15, 21, 35, 50 and 100 % by volume in nitrogen diluent gas. Particles ignited and burned brightly, with peak temperatures reaching 2344–2884 K, depending on the oxygen concentration. The observed distribution of the combustion products of iron was bimodal in size and composition, containing (a) dark gray spherical micrometric particles bigger than their iron particle precursors composed of both magnetite and hematite, and (b) highly agglomerated orange-reddish nanometric particles composed of hematite. The mass fraction of nanometric particles accounted for up to 1.7–7.4 % of the collected products, increasing with the oxygen partial pressure. The nanometric particles were spherules, 30–100 nm in diameter. However, they were highly agglomerated with aggregate aerodynamic diameters peaking at 180–560 nm. The yield of nanoparticles increased with increasing oxygen concentration in the furnace. A heuristic model was used to investigate the impact and sensitivity of various strategies for modeling evaporation, aiming to identify key mechanisms that limit the evaporation rate. This study highlights that understanding the type of liquid at the particle surface is crucial, as evaporation can increase significantly with a homogeneous liquid Fe-O particle compared to a core–shell morphology. Additionally, the analysis suggests that evaporation likely occurs in an intermediate regime where gaseous Fe-containing species oxidize in the boundary layer. Understanding these boundary layer processes is essential for accurately modeling the evaporation rate while maintaining computational efficiency. 1. 

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4. Modeling Solution Drying by Moving a Liquid-Vapor Interface: Method and Applications

   https://doi.org/10.3390/polym14193996  

   Tang, Yanfei; McLaughlan, John E.; Grest, Gary S.; Cheng, Shengfeng (October 2022, Polymers)

   A method of simulating the drying process of a soft matter solution with an implicit solvent model by moving the liquid-vapor interface is applied to various solution films and droplets. For a solution of a polymer and nanoparticles, we observe “polymer-on-top” stratification, similar to that found previously with an explicit solvent model. Furthermore, “polymer-on-top” is found even when the nanoparticle size is smaller than the radius of gyration of the polymer chains. For a suspension droplet of a bidisperse mixture of nanoparticles, we show that core-shell clusters of nanoparticles can be obtained via the “small-on-outside” stratification mechanism at fast evaporation rates. “Large-on-outside” stratification and uniform particle distribution are also observed when the evaporation rate is reduced. Polymeric particles with various morphologies, including Janus spheres, core-shell particles, and patchy particles, are produced from drying droplets of polymer solutions by combining fast evaporation with a controlled interaction between the polymers and the liquid-vapor interface. Our results validate the applicability of the moving interface method to a wide range of drying systems. The limitations of the method are pointed out and cautions are provided to potential practitioners on cases where the method might fail. 

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5. Remote controlled optical manipulation of bimetallic nanoparticle catalysts using peptides

   https://doi.org/10.1039/D1CY00189B  

   Lawrence, Randy L.; Olagunju, Mary O.; Liu, Yang; Mahalingam, Krishnamurthy; Slocik, Joseph M.; Naik, Rajesh R.; Frenkel, Anatoly I.; Knecht, Marc R. (April 2021, Catalysis Science & Technology)

   null (Ed.)

   Bimetallic nanoparticles remain a promising avenue to achieve highly reactive catalysts. In this contribution, we demonstrate the use of a photoswitchable peptide for the production of PdAu bimetallic nanoparticles at a variety of Pd : Au ratios. Using this peptide, the biomolecular overlayer structure can be switched between two different conformations ( cis vs. trans ) via light irradiation, thus accessing two different surface structures. The composition and arrangement of the materials was fully characterized, including atomic-level analyses, after which the reactivity of the bimetallic materials was explored using the reduction of 4-nitrophenol as a model system. Using these materials, it was demonstrated that the reactivity was maximized for the particles prepared at a Pd : Au ratio of 1 : 3 and with the peptide in the cis conformation. Such results present routes to a new generation of catalysts that could be remotely activated for on/off reactivity as a function of the ligand overlayer conformation. 

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