Many oxidation catalysts rely on ceria nanomaterials as efficient supports for platinum group metal nanoparticles, where morphology affects the catalytic performance. Rational exploitation of the chemical parameter space enables the tuning and control of these morphological features. This study presents a systematic investigation of conventional and microwave‐assisted hydrothermal syntheses of ceria nanorods and nanocubes. The specific role of Ce(III) counter‐ions in nanorod formation was systematically investigated, identifying chloride ions as essential for anisotropic growth. Microwave heating proved superior to conventional methods, yielding high‐aspect‐ratio rods in 10 min while preventing the surface area loss associated with thermal coarsening. For the nanocubes, an acid‐buffered route was developed to narrow the polydispersity. The reactor filling ratio in the microwave syntheses emerged as a key parameter to modulate solvent evaporation, allowing tuning of the nanocube size (from 14 to 26 nm) and truncation degree. Structural and morphological characterisation by X‐ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller specific surface area analysis (BET) confirmed the formation of highly crystalline and porous nanomaterials, providing a rational framework for the synthesis of ceria nanostructures with controlled morphology via microwave‐assisted heating. The effect of autogenous pressure was rationalised by numerical calculations using a Python script developed by the authors.

The single‐step syngas‐to‐dimethyl ether (STD) process offers both economic and technical advantages over the current two‐step industrial process that utilizes Cu/ZnO/Al2O3 catalysts. Here, we report a highly active bifunctional Pd/CeO2/γ‐Al2O3 catalyst, in which Pd colloids dispersed in a nanoscale CeO2 matrix serve as the key building block for the methanol‐active component, efficiently catalysing the STD reaction. For Pd/CeO2/γ‐Al2O3 with a high Pd‐CeO2 interface concentration, CO conversion and dimethyl ether yield are significantly increased compared to Pd supported on Al2O3. Systematic investigations using spectroscopic and microscopic techniques reveal the formation of highly dispersed palladium clusters/particles confined within the nanoparticulate CeO2 matrix. The superior catalytic performance in both activity and stability observed for the Pd/CeO2/γ‐Al2O3 in the STD reaction stems from the active cationic palladium interfacial species and the presence of adjacent O vacancies.

Atomically precise clusters such as [Pt17(CO)12(PPh3)8] x+ (x = 1,2) (PPh3 is triphenylphosphine) are known as precursors for making oxidation catalysts. However, the changes occurring to the cluster upon thermal activation during the formation of the active catalyst are poorly understood. We have used a combination of hybrid mass spectrometry and surface science to map the thermal decomposition of [Pt17(CO)12(PPh3)8](NO3)2. High-resolution mass and ion mobility spectrometry together with DFT-based modeling were used to probe the sequence of fragmentation reactions and fragment structures generated upon collisional excitation of [Pt17(CO)12(PPh3)8]2+. This was compared with thermal desorption spectroscopy of [Pt17(CO)12(PPh3)8](NO3)2 dropcast onto an inert graphite surface. In both cases, a characteristic sequence of CO and benzene desorption steps is observed followed at higher excitation energy by H2 loss. This behavior is indicative of Pt-catalyzed C-H activation of phenyl groups during partial stripping of the ligand shell while the Pt17P8 cluster core is retained.

Due to its peculiar properties and strong interaction with noble metals, ceria is widely used as a catalyst support for numerous applications. In this work, morphologically pure and highly crystalline ceria nanocubes and nanorods were prepared to systematically investigate both the impact of the support morphology and Pd-Pt interaction degree on the noble metal-support interplay during CO oxidation. By using a constant surface noble metal concentration, the same probability for cluster/nanoparticle formation or noble metal redispersion during catalyst pretreatment and under reaction conditions was ensured. This novel approach allows for highlighting the impact of the support morphology on the catalyst dynamics and reveals different activity trends compared to what was previously reported for monometallic Pd- or Pt-catalysts supported on CeO2. In particular, complementary ex situ and in situ/operando characterization tools combined with catalytic tests uncovered that by tuning the morphology and surface characteristics of ceria, the clustering and redispersion of the deposited noble metals in different atmospheres (e.g., oxidizing/reducing) can be controlled. The initial state and corresponding catalyst dynamics were thoroughly probed, showing that by depositing Pt and Pd on CeO2-nanocubes, a balanced noble metal-support interaction is obtained that promotes the formation and retention of small and active noble metal clusters, regardless of the initial Pd-Pt interaction. In contrast, a high number of surface defects, as evidenced by Raman spectroscopy for CeO2-nanorods, fosters the formation of highly dispersed species with a decreased low-temperature activity. Pd and Pt species with minimal mutual interaction performed better during CO oxidation, while the presence of alloyed particles on ceria prevented rapid noble metal redispersion and thus catalyst deactivation. Based on a rational adjustment of the noble metal-support interaction, the findings of this study are expected to contribute to the future development of NM/CeO2-based catalysts containing the desired active sites, i.e., highly dispersed species or nanoparticles.

Subnanometer clusters with precise atom numbers hold immense potential for applications in catalysis, as single atoms can significantly impact catalytic properties. Typically, inorganic clusters are produced using batch processes with high dilutions, making the scale-up of these processes time-consuming and its reproducibility challenging. While continuous-flow systems have been employed for organic synthesis and, more recently, nanoparticle preparation, these approaches have only rarely been applied to cluster synthesis. In a flexible, continuous flow synthesis platform, we integrate multiple continuous stirred tank reactors (CSTR) into a cascade to synthesize clusters with a precise number of atoms, demonstrating the potential of this approach for atom precise cluster synthesis and expanding the application of continuous-flow systems beyond organic synthesis.

The synthesis of renewable bio-based monomers, like 2,5-furandicarboxylic acid (FDCA), is of high interest in the shift toward a circular economy. Bimetallic catalysts offer the variation of different properties, enabling the design of tailor-made catalysts. The combination of silver and palladium, both highly active for specific liquid-phase oxidation reactions, shows promise for superior performance in the selective oxidation of 5-(hydroxymethyl)furfural (HMF) to FDCA. While Ag/CBA and Ag3Pd1/CBA, supported on carbon black acetylene (CBA), were active only for the oxidation of the aldehyde group of HMF, increasing the Pd-fraction allowed for the oxidation of the alcohol group as well. In-depth characterization by X-ray diffraction, electron microscopy, and X-ray absorption spectroscopy revealed a synergistic effect between Ag and Pd in Pd-rich alloys, leading to an enhanced performance. Pd is particularly effective in activating oxygen, the oxidizing agent, while Ag ensures a high selectivity in the dehydrogenation reaction. Moreover, removing residual surfactants from the synthesized catalysts by increasing the calcination temperature further enhanced the activity. This study demonstrates the potential of tuning the catalytic properties of noble metal-based catalysts for optimizing liquid-phase oxidation reactions.

Hydrogen generation in electrostatically stabilized, aqueous organic nanoparticle dispersions is investigated. For this purpose, organic nanoparticle dispersions are synthesized in water by nanoprecipitation from tetrahydrofuran and stabilized by charging through strong molecular electron acceptors. The dispersions are stable for more than 10 weeks on the shelf and during the photocatalytic process, despite the continuous transfer of charges between the reactants. The hydrogen generation in the electrostatically stabilized dispersions outperforms the hydrogen generation in organic nanoparticle dispersions which contain the common stabilizer sodium dodecyl sulfate.

Following the 'precursor' concept, a series of Pd/Zn-based, colloidal nanoparticles (NPs) with different Zn/Pd molar ratios were synthesized by reductive stabilization and used as precursors for the methanol active component in bifunctional catalysts. The bifunctional catalysts for the single-step dimethyl ether synthesis from CO-rich syngas were obtained by immobilizing the NPs on a microporous or hierarchical HZSM-5 zeolite, which were used as dehydration catalysts. The catalysts were characterized, e.g., by (in situ) powder X-ray diffraction, scanning and transmission electron microscopy with energy-dispersive X-ray analysis, N2 physisorption, and NH3 temperature programmed desorption. This study demonstrates the influence of the Zn/Pd molar ratio on the size of PdZn particles formed under reaction conditions, which correlates with the catalytic performance in the STD process. The introduction of mesopores in the hierarchical zeolite by desilication of HZSM-5 increased the DME yield while decreasing the selectivity to hydrocarbons.

An important goal for the development of novel nanomaterials based on magnetic nanoparticles dispersed in liquid crystals is the improvement of the sensitivity to magnetic fields. Despite the continuous research of the magnetically-controlled properties of such hybrid composite materials, known as ferronematics, a persistent challenge lies in achieving consistent homogeneity and colloidal stability of the nanoparticles in liquid crystal media. Therefore, the design of the magnetic nanoparticles needs to be compatible with the liquid crystal matrix. Coating nanoparticles with (pro)mesogenic ligands has been shown to be a versatile way of stabilizing magnetic nanoparticles in liquid crystal matrices. Here, we report about the effect of dendrimer-functionalized cobalt ferrite nanoparticles (CoFe2O4@dend) on structure and magnetic sensitivity in the thermotropic liquid crystal 4-pentyl-4′-cyanobiphenyl (5CB) confirmed by small angle X-ray scattering (SAXS), magnetization and capacitance measurements. Our measurements reveal that for dendronized magnetic nanoparticles, the sensitivity to magnetic fields is improved. However, they exhibit a tendency to form clusters in the liquid crystal medium. These clusters induce a tilting of the overall ordering of the nematic director field due to magneto-nematic coupling.

Formaldehyde is one of the most important intermediates in today's chemical industry and mainly produced via the silver or Formox process. In this study, we introduce titania as a new catalyst for the oxidative dehydrogenation (ODH) of methanol to formaldehyde. Bulk titania catalysts were tested under methanol ODH conditions and the influence of reaction temperature, residence time and feed composition was investigated. The highest formaldehyde yield exhibited in the titania-catalyzed methanol ODH was around 70 % at 600 & DEG;C, 1.6 gCatalyst h molMethanol  1 and 2.0 molMethanol molOxygen stability. While catalyst deactivation was observed at 600 & DEG;C (90-60 % methanol conversion after 72 h) and 550 & DEG;C (90-85 % methanol conversion after 72 h), methanol conversion (85 %) was stable and no deactivation occurred at 500 & DEG;C. Characterization of the used catalysts by nitrogen physisorption, powder X-ray diffraction and thermogravimetric analysis revealed deposition of carbon species as the main cause of catalyst deactivation. By alternating reaction and regeneration with oxygen, constant methanol conversions (90 %) and formaldehyde yields (70 %) were achieved at 600 & DEG;C.

Hydrogen peroxide (H2O2) is a green oxidant, widely used in industry. To turn its synthesis green, research focused on the development of efficient catalysts for the two-electron oxygen reduction reaction (2e-ORR) to produce H2O2 from water and molecular oxygen. Despite recent progress, electrolyte effects of the electrochemical H2O2 production have remained little understood. We report a significant effect of alkali metal cations (AMCs) on the electrocatalytic H2O2 production on carbon catalysts in acidic environments. The presence of AMCs at the electrified carbon interface shift the half wave potential of the 2e-ORR from -0.48 V to -0.22 VRHE. This cationic induced enhancement effect exhibits a uniquely sensitive on/off switching behaviour depending on the voltammetric protocol. Voltammetric and direct in situ X-ray photoemission spectroscopic evidence is presented that supports a controlling role of the potential of zero charge (PZC) of the catalytic enhancement. Depending whether the electrode potential is kept cathodic or even just briefly reaches values anodic of the PZC, AMCs accumulate at the electrified interface and enhance the 2e-ORR or get repelled away from it, respectively. Density functional theory calculations associate the enhancement by the stabilization of the *OOH key intermediate. Based on this finding, we developed a refined reaction mechanism for the H2O2 production in presence of AMCs.

Supported coinage-metal catalysts were prepared by strong electrostatic adsorption and used to assess the performance of silver and copper in the oxidative dehydrogenation of methanol to formaldehyde.

The integration of nanoparticles with magnetic, ferroelectric or semiconducting properties into liquid crystals (LCs) has attracted great interest both for fundamental investigations and for technological applications. Here, an overview of hybrid materials based on magnetic nanoparticles (MNPs) and thermotropic LCs is given. After a general introduction to thermotropic LCs and LC-MNP hybrid materials, various preparation methods established by us are presented. The synthesis of shape-(an)isotropic MNPs, their functionalization by tailored (pro)mesogenic ligands with linear or dendritic structures and their integration into LC hosts are discussed. The characterization of the MNPs, (pro)mesogenic ligands and resulting MNP-LC hybrid materials is described to show the influence of MNP functionalization on the MNP-LC interactions including aspects such as colloidal stability and structuring in the LC host. Overall, we show that the physical properties of the hybrid material are significantly influenced not only by the MNPs (i.e., their size, shape and composition) but also by their surface properties (i.e., the structure of the (pro)mesogenic ligands).

The preparation of bimetallic Pd/Ag-based model catalysts is addressed to study the promotional effects of Ag doping in the liquid-phase semi-hydrogenation of diphenylacetylene. The precursor concept is employed where colloidal bimetallic Pd/Ag nanoparticles are initially synthesized and then used as well-defined building units for catalyst preparation. This approach allows for tuning the composition of the nanoparticles independently with the two metals co-localized to a fine extent. Size and composition of the nanoparticles are preserved after immobilizing them on a carbon support.

Intermetallic nanoparticles (NPs) are highly interesting materials in catalysis due to their geometrically ordered structures and altered electronic properties, but the synthesis of defined intermetallic NPs remains a challenge. Here, we report a novel and facile approach for the synthesis of intermetallic Pd-In NPs in ionic liquids (ILs) at moderate temperatures. Depending on the molar ratio of the metal precursors and the reaction temperature, single-phase Pd3In, PdIn and Pd3In7 NPs were obtained, which was confirmed, e.g. by powder X-ray diffraction, electron microscopy, and optical emission spectroscopy with inductively coupled plasma. The Pd-In NPs stabilized in ILs were used as catalysts in the liquid-phase semi-hydrogenation of diphenylacetylene (DPA). Highly ordered PdIn NPs with a CsCl type structure revealed both high activity and selectivity to cis-stilbene even at full DPA conversion. Intermetallic compounds such as PdIn can be used to isolate contiguous Pd atoms with another base metal into single Pd sites, thereby increasing the catalytic selectivity of Pd while stabilizing the individual sites in the intermetallic structures. This work may provide new pathways for the synthesis of single-phase intermetallic NPs and future insights into a more rational design of bimetallic catalysts with specific catalytic properties.

TiO2 hollow nanosphere (HNS) are prepared via NaCl templates in a one-pot approach. The NaCl templates are realized by solvent/anti-solvent strategies and coated with TiO2via controlled hydrolysis of Ti-alkoxides. The NaCl template can be easily removed by washing with water, and the TiO2 HNS are finally impregnated with Pd/Pt. Electron microscopy shows TiO2 HNS with an outer diameter of 140-180 nm, an inner cavity of 80-100 nm, and a wall thickness of 30-40 nm. The TiO2 HNS exhibit high surface area (up to 370 m2 g-1) and pore volume (up to 0.28 cm3 g-1) with well-distributed small Pd/Pt nanoparticles (Pt: 3-4 nm, Pd: 3-7 nm). H2O2 direct synthesis (room temperature, liquid phase) and CO oxidation (up to 300 °C, gas phase) are used to probe the catalytic properties and result in a good stability of the HNS structure as well as a promising performance with a H2O2 selectivity of 63% and a productivity of 3390 mol kgPd-1 h-1 (TiO2-Pd HNS, 5 wt%) as well as CO oxidation light-out temperatures of 150 °C (TiO2-Pt HNS, 0.7 wt%).

Self-assembly is one of the crucial mechanisms allowing to design multifunctional materials. Soft hybrid materials contain components of different nature and exhibit competitive interactions which drive self-organisation into structures of a particular function. Here we demonstrate a novel type of a magnetic hybrid material where the molecular tilt can be manipulated through a delicate balance between the topologically-assisted colloidal self-assembly of \rev{magnetic nanoparticles} and the anisotropic molecular interactions in a liquid crystal matrix.

Hydrogen peroxide production by direct synthesis (H2 + O2 → H2O2) is a promising alternative to the commercialized indirect process involving sequential hydrogenation and oxidation of anthraquinone...

In alloyed nanoparticles, synergistic electronic and/or geometric effects may enhance the catalytic properties compared to their monometallic counterparts. Herein, we address the synthesis of bimetallic Au/Cu nanoparticles with different compositions by wet chemical reduction in ionic liquids. The nanoparticles were successively supported on carbon. The ionic liquid could be recycled after synthesis. Annealing of the carbon-supported NPs at 400 degrees C led to NPs of the ordered intermetallic L1(0) AuCu phase. The nanoparticle-derived catalysts were characterized by X-ray diffraction analysis, transmission electron microscopy, X-ray photoelectron spectroscopy and optical emission spectroscopy with inductively coupled plasma. Oxidation of biomass-derived furans is a prominent process for biomass transformation into value-added chemicals. Herein, the oxidation of 5-hydroxymethyl-2-furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) was chosen as a model reaction to evaluate the effect of Cu addition and intermetallic structure on the catalytic performance. Particularly Au/Cu nanoparticles with an Au/Cu ratio of 3 : 1 showed very high conversion to FDCA.