Although gold nanoparticles (GNP) are among the most intensely studied nanoscale materials, actual mechanisms of GNP formation often remain unclear due to limited accessibility in situ-derived time-resolved information about precursor conversion and particle size distribution. Overcoming such limitations, a method is presented that analyzes via situ SAXS XANES using synchrotron radiation. The applied study classical synthesis route reduction tetrachloroauric acid by trisodium citrate at...

Ni-Fe oxyhydroxides are the most active known electrocatalysts for oxygen evolution reaction (OER) in alkaline electrolytes and therefore of great scientific technological importance context electrochemical energy conversion. Here we uncover, investigate, discuss previously unaddressed effects conductive supports electrolyte pH on Ni-Fe(OOH) catalyst redox behavior catalytic OER activity, combining situ UV-vis spectro-electrochemistry, operando mass spectrometry (DEMS), cryo X-ray absorption...

A very high catalytic activity in the cyanosilylation reaction was observed for MIL-101, a chromium based metal-organic framework; moreover, MIL-101 is also remarkably stable support palladium hydrogenation reactions, with significantly higher than e.g. on activated carbon.

Electrochemical hydrogen peroxide (H2O2) production by two-electron oxygen reduction is a promising alternative process to the established industrial anthraquinone process. Current challenges relate finding cost-effective electrocatalysts with high electrocatalytic activity, stability, and product selectivity. Here, we explore activity selectivity toward H2O2 of number distinct nitrogen-doped mesoporous carbon catalysts report previously unachieved ∼95–98% in acidic solution. To explain our...

In the future, (electro-)chemical catalysts will have to be more tolerant towards a varying supply of energy and raw materials. This is mainly due fluctuating nature renewable energies. For example, power-to-chemical processes require shift from steady-state operation under dynamic reaction conditions. brings along number demands for design both reactors, because it well-known that structure very dynamic. However, in-depth studies catalytic reactors such transient conditions only started...

Gold nanoparticles (AuNP) were prepared by the homogeneous mixing of continuous flows an aqueous tetrachloroauric acid solution and a sodium borohydride applying microstructured static mixer. The online characterization screening this fast process (∼2 s) was enabled coupling micromixer operating in continuous-flow mode with conventional in-house small angle X-ray scattering (SAXS) setup. This technique enables time-resolved investigation growth from average radius ca. 0.8 nm to about 2 nm....

This contribution provides a comprehensive mechanistic picture of the gold nanoparticle synthesis by citrate reduction HAuCl4, known as Turkevich method, addressing five key questions. The leads to monodisperse final particles result seed-mediated growth mechanism. In initial phase synthesis, seed are formed onto which residual is distributed during course reaction. It shown that this mechanism fortunate coincidence created favorable interplay several chemical and physicochemical processes...

The formation mechanisms of silver nanoparticles using aqueous perchlorate solutions as precursors and sodium borohydride reducing agent were investigated based on time-resolved in situ experiments. This contribution addresses two important issues colloidal science: (i) differences analogies between growth processes different metals such gold (ii) the influence a steric stabilizing process. results reveal that due to coalescence is fundamental principle if monomer-supplying chemical reaction...

Mesoporous carbons synthesized via a soft-templating approach have attracted much attention due to their easy synthesis and facile control over the derived pore structure. In analogy approaches for mesoporous metal oxides, is based on sequence of forming supramolecular arrangements precursor molecules with soft templates, stabilization framework by polymerization finally removal templates. Using micelles amphiphilic block-copolymers as morphology size mesopores can be achieved e.g....

The morphology, crystallinity, and chemical state of well-defined Ir oxide nanoscale thin-film catalysts prepared on Ti substrates at various calcination temperatures were investigated. Special emphasis was placed the temperature-dependent interaction between film substrate its impact electrocatalytic oxygen evolution reaction (OER) activity. films characterized by scanning electron microscopy, transmission energy dispersive X-ray spectroscopy, diffraction, photoelectron spectroscopy cyclic...

Synthesis of mesoporous iridium oxide films via soft templating and evaporation-induced self-assembly is demonstrated employing an amphiphilic triblock-copolymer PEO-PB-PEO. Films possess nanocrystalline walls feature locally ordered pores about 16 nm diameter. Analysis the film properties by SEM, TEM, EDX, XPS, SAXS, XRD, BET along thermal treatment that succeeds dipcoating shows polymer template removed calcination between 200 300 °C, accompanied uniaxial shrinkage pore system...

Abstract Iridium oxide is the catalytic material with highest stability in oxygen evolution reaction (OER) performed under acidic conditions. However, its high cost and limited availability demand that IrO 2 utilized as efficiently possible. We report synthesis OER performance of highly active mesoporous catalysts optimized surface area, intrinsic activity, pore accessibility. Catalytic layers controlled size were obtained by soft‐templating micelles formed from amphiphilic block copolymers...

Chlorine evolution is one of the most important electrochemical reactions applied in industry. We present a method for synthesis chlorine catalysts with improved performance. The performance increase results from introduction controlled mesoporosity into pore system Ru- and Ir-containing TiO2 by templating micelles amphiphilic block-copolymers. Micelle-templated TiO2-based were synthesized loadings up to 15 wt % either Ru, Ir, or combination both active metals. catalysts’ walls are composed...

Metal nanoparticles have attracted much attention due to their unique properties. Size control provides an effective key accurate adjustment of colloidal The common approach size is testing different sets parameters via trial and error. actual particle growth mechanisms, in particular the influences synthesis on process, remain a black box. As result, precise rarely achieved for most metal nanoparticles. This contribution presents that based mechanistic knowledge. It exemplified silver...

Abstract Decades of catalysis research have created vast amounts experimental data. Within these data, new insights into property-performance correlations are hidden. However, the incomplete nature and undefined structure data has so far prevented comprehensive knowledge extraction. We propose a meta-analysis method that identifies between catalyst’s physico-chemical properties its performance in particular reaction. The unites literature with textbook statistical tools. Starting from...

Abstract Modern research methods produce large amounts of scientifically valuable data. Tools to process and analyze such data have advanced rapidly. Yet, access high‐quality remains limited in many fields, including catalysis research. Implementing the concept FAIR (Findable, Accessible, Interoperable, Reusable) community would improve this situation dramatically. The German NFDI initiative (National Research Data Infrastructure) aims create a unique infrastructure covering all scientific...

Catalytic ammonia oxidation over platinum has been studied experimentally from UHV up to atmospheric pressure with polycrystalline Pt and the single crystal orientations (533), (443), (865), (100). Density functional theory (DFT) calculations explored reaction pathways on Pt(111) Pt(211). It was shown, both in experimentally, that is activated by adsorbed oxygen, i.e. Oad or OHad. In situ XPS 1 mbar showed existence of NHx (x = 0,1,2,3) intermediates Pt(533). Based a mechanism activation via...

Abstract The synthesis and properties of a series new structure‐directing triblock copolymers with PEO‐PB‐PEO structure (PEO = poly(ethylene oxide) PB polybutadiene) their application as superior pore‐templates for the preparation mesoporous titania coatings are reported. Starting from either TiCl 4 or preformed TiO 2 nanocrystalline building blocks, crystalline titanium oxide films significant degree mesoscopic ordered pores derived, pore size can be controlled by molecular mass template...

Control over the size of active metal particles and structure catalysts pore system is an essential requirement for design supported catalysts. Polymeric templates combined with a suitable metal-oxide precursor enable synthesis defined systems, whereas colloidal can provide access to particle-size control. However, template, precursor, in one solution are often not compatible each other due aggregation, precipitation, dissolution processes. We present new approach preparation that permits...

Abstract The performance of electrochemical reactions depends strongly on the morphology and structure employed catalytic electrodes. Nanostructuring electrode surface represents a powerful tool to increase electrochemically active area Moreover, it can also facilitate faster diffusive mass transport inside three‐dimensional This minireview describes recent trends in development synthesis routes for porous nanostructured materials discusses respective important electrocatalytic applications....

Abstract Non‐woven carbon nanofiber networks were produced by electrospinning. Electrospinning is a process that can easily be up‐scaled, producing fibers used as electrodes with increased surface area and reaction sites. The structure of electrospun nanofibers (ES‐CNFs) was investigated scanning electron microscopy compared to commercial felt (CF). electrochemical properties the obtained ES‐CNFs studied for negative half‐cell in three‐electrode setup single‐cell battery test system....

This contribution investigates the growth mechanism of Turkevich method. The experimental results provide missing piece mechanistic puzzle which enables actual control particle in commonly used Applying gained knowledge, boundary conditions for a successful synthesis are deduced. Moreover, under method is highly reproducible derived. Following these conditions, modified to reveal small monodisperse particles with an unprecedented reproducibility ±0.1 nm.

Abstract A facile approach for the template‐free synthesis of highly active non‐noble metal based oxygen reduction reaction (ORR) electrocatalysts is presented. Porous Fe−N−C/Fe/Fe 3 C composite materials are obtained by pyrolysis defined precursor mixtures polyformamidine (PFA) and FeCl as nitrogen‐rich carbon iron sources, respectively. Selection temperature (700–1100 °C) loading (5–30 wt%) yields with differing surface areas, porosity, graphitization degree, nitrogen content, well ORR...

Abstract In situ x-ray spectroscopies offer a powerful way to understand the electronic structure of electrode–electrolyte interface under operating conditions. However, most techniques require vacuum, making it necessary design spectro-electrochemical cells with delicate wet electrochemical environment. The cell often dictates what measurements can be done and which processes studied. Hence, is important pick right for process interest. To facilitate this choice, highlight challenges in...