Publications

@article{Raab2023,

title = {Emergence of chaos in a compartmentalized catalytic reaction nanosystem},

author = {Maximilian Raab and Johannes Zeininger and Yuri Suchorski and Keita Tokuda and Günther Rupprechter},

doi = {10.1038/s41467-023-36434-y},

year  = {2023},

date = {2023-02-10},

urldate = {2023-02-01},

journal = {Nature Communications},

volume = {14},

pages = {736--745},

publisher = {Springer Science and Business Media LLC},

abstract = {In compartmentalized systems, chemical reactions may proceed in differing ways even in adjacent compartments. In compartmentalized nanosystems, the reaction behaviour may deviate from that observed on the macro- or mesoscale. In situ studies of processes in such nanosystems meet severe experimental challenges, often leaving the field to theoretical simulations. Here, a rhodium nanocrystal surface consisting of different nm-sized nanofacets is used as a model of a compartmentalized reaction nanosystem. Using field emission microscopy, different reaction modes are observed, including a transition to spatio-temporal chaos. The transitions between different modes are caused by variations of the hydrogen pressure modifying the strength of diffusive coupling between individual nanofacets. Microkinetic simulations, performed for a network of 52 coupled oscillators, reveal the origins of the different reaction modes. Since diffusive coupling is characteristic for many living and non-living compartmentalized systems, the current findings may be relevant for a wide class of reaction systems.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Maqbool2023,

title = {\textit{Operando} monitoring of a room temperature nanocomposite methanol sensor},

author = {Qaisar Maqbool and Nevzat Yigit and Michael Stöger-Pollach and Maria Letizia Ruello and Francesca Tittarelli and Günther Rupprechter},

doi = {10.1039/d2cy01395a},

year  = {2023},

date = {2023-02-07},

urldate = {2023-02-07},

journal = {Catalysis Science & Technology},

volume = {13},

issue = {3},

pages = {624--636},

publisher = {Royal Society of Chemistry (RSC)},

abstract = {The sensing of volatile organic compounds by composites containing metal oxide semiconductors is typically explained via adsorption–desorption and surface electrochemical reactions changing the sensor's resistance. The analysis of molecular processes on chemiresistive gas sensors is often based on indirect evidence, whereas \textit{in situ} or \textit{operando} studies monitoring the gas/surface interactions enable a direct insight. Here we report a cross-disciplinary approach employing spectroscopy of working sensors to investigate room temperature methanol detection, contrasting well-characterized nanocomposite (TiO_{2}@rGO-NC) and reduced-graphene oxide (rGO) sensors. Methanol interactions with the sensors were examined by (quasi) \textit{operando}-DRIFTS and \textit{in situ}-ATR-FTIR spectroscopy, the first paralleled by simultaneous measurements of resistance. The sensing mechanism was also studied by mass spectroscopy (MS), revealing the surface electrochemical reactions. The \textit{operando} and \textit{in situ} spectroscopy techniques demonstrated that the sensing mechanism on the nanocomposite relies on the combined effect of methanol reversible physisorption and irreversible chemisorption, sensor modification over time, and electron/O_{2} depletion–restoration due to a surface electrochemical reaction forming CO_{2} and H_{2}O.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Corrias2023,

title = {Automated Real-Space Lattice Extraction for Atomic Force Microscopy Images},

author = {Marco Corrias and Lorenzo Papa and Igor Sokolovíc and Viktor Birschitzky and Alexander Gorfer and Martin Setvin and Michael Schmid and Ulrike Diebold and Michele Reticcioli and Cesare Franchini},

doi = {10.1088/2632-2153/acb5e0},

year  = {2023},

date = {2023-01-24},

urldate = {2023-01-24},

journal = {Machine Learning: Science and Technology},

volume = {4},

pages = {015015},

abstract = {Analyzing atomically resolved images is a time-consuming process requiring solid experience and substantial human intervention. In addition, the acquired images contain a large amount of information such as crystal structure, presence and distribution of defects, and formation of domains, which need to be resolved to understand a material's surface structure. Therefore, machine learning techniques have been applied in scanning probe and electron microscopies during the last years, aiming for automatized and efficient image analysis. This work introduces a free and open source tool (AiSurf: Automated Identification of Surface Images) developed to inspect atomically resolved images via Scale-Invariant Feature Transform (SIFT) and Clustering Algorithms (CA). AiSurf extracts primitive lattice vectors, unit cells, and structural distortions from the original image, with no pre-assumption on the lattice and minimal user intervention. The method is applied to various atomically resolved non-contact atomic force microscopy (AFM) images of selected surfaces with different levels of complexity: anatase TiO_{2}(101), oxygen deficient rutile TiO_{2}(110) with and without CO adsorbates, SrTiO_{3}(001) with Sr vacancies and graphene with C vacancies. The code delivers excellent results and is tested against atom misclassification and artifacts, thereby facilitating the interpretation of scanning probe microscopy images.},

keywords = {P02, P07},

pubstate = {published},

tppubtype = {article}

}

@article{Schmid2022,

title = {Analysis of Temperature-Programmed Desorption via Equilibrium Thermodynamics},

author = {Michael Schmid and Gareth S. Parkinson and Ulrike Diebold},

doi = {10.1021/acsphyschemau.2c00031},

year  = {2022},

date = {2022-11-15},

journal = {ACS Physical Chemistry Au},

volume = {3},

issue = {1},

pages = {44--62},

publisher = {American Chemical Society (ACS)},

abstract = {Temperature-programmed desorption (TPD) experiments in surface science are usually analyzed using the Polanyi–Wigner equation and/or transition-state theory. These methods are far from straightforward, and the determination of the pre-exponential factor is often problematic. We present a different method based on equilibrium thermodynamics, which builds on an approach previously used for TPD by Kreuzer et al. (\textit{Surf. Sci.}\textbf{1988}). Equations for the desorption rate are presented for three different types of surface–adsorbate interactions: (i) a 2D ideal hard-sphere gas with a negligible diffusion barrier, (ii) an ideal lattice gas, that is, fixed adsorption sites without interaction between the adsorbates, and (iii) a lattice gas with a distribution of (site-dependent) adsorption energies. We show that the coverage dependence of the sticking coefficient for adsorption at the desorption temperature determines whether the desorption process can be described by first- or second-order kinetics. The sticking coefficient at the desorption temperature must also be known for a quantitative determination of the adsorption energy, but it has a rather weak influence (like the pre-exponential factor in a traditional TPD analysis). Quantitative analysis is also influenced by the vibrational contributions to the energy and entropy. For the case of a single adsorption energy, we provide equations to directly convert peak temperatures into adsorption energies. These equations also provide an approximation of the desorption energy in cases that cannot be described by a fixed pre-exponential factor. For the case of a distribution of adsorption energies, the desorption spectra cannot be considered a superposition of desorption spectra corresponding to the different energies. Nevertheless, we present a method to extract the distribution of adsorption energies from TPD spectra, and we rationalize the energy resolution of TPD experiments. The analytical results are complemented by a program for simulation and analysis of TPD data.},

keywords = {P02, P04},

pubstate = {published},

tppubtype = {article}

}

@article{Zeininger2022,

title = {Reaction Modes on a Single Catalytic Particle: Nanoscale Imaging and Micro-Kinetic Modeling},

author = {Johannes Zeininger and Maximilian Raab and Yuri Suchorski and Sebastian Buhr and Michael Stöger-Pollach and Johannes Bernardi and Günther Rupprechter},

doi = {10.1021/acscatal.2c02901},

year  = {2022},

date = {2022-10-07},

journal = {ACS Catalysis},

volume = {12},

number = {20},

pages = {12774--12785},

publisher = {American Chemical Society (ACS)},

abstract = {The kinetic behavior of individual Rh(\textit{hkl}) nanofacets coupled in a common reaction system was studied using the apex of a curved rhodium microcrystal (radius of 0.65 μm) as a model of a single catalytic particle and field electron microscopy for in situ imaging of catalytic hydrogen oxidation. Depending on the extent of interfacet coupling via hydrogen diffusion, different oscillating reaction modes were observed including highly unusual multifrequential oscillations: differently oriented nanofacets oscillated with differing frequencies despite their immediate neighborhood. The transitions between different modes were induced by variations in the particle temperature, causing local surface reconstructions, which create locally protruding atomic rows. These atomic rows modified the coupling strength between individual nanofacets and caused the transitions between different oscillating modes. Effects such as entrainment, frequency locking, and reconstruction-induced collapse of spatial coupling were observed. To reveal the origin of the different experimentally observed effects, microkinetic simulations were performed for a network of 105 coupled oscillators, modeling the individual nanofacets communicating via hydrogen surface diffusion. The calculated behavior of the oscillators, the local frequencies, and the varying degree of spatial synchronization describe the experimental observations well.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Zeininger2022a,

title = {Pattern Formation in Catalytic H_{2} Oxidation on Rh: Zooming in by Correlative Microscopy},

author = {Johannes Zeininger and Philipp Winkler and Maximilian Raab and Yuri Suchorski and Mauricio J. Prieto and Liviu C. Tănase and Lucas Souza Caldas and Aarti Tiwari and Thomas Schmidt and Michael Stöger-Pollach and Andreas Steiger-Thirsfeld and Beatriz Roldan Cuenya and Günther Rupprechter},

doi = {10.1021/acscatal.2c03692},

year  = {2022},

date = {2022-09-19},

urldate = {2022-09-19},

journal = {ACS Catalysis},

volume = {12},

number = {19},

pages = {11974--11983},

publisher = {American Chemical Society (ACS)},

abstract = {Spatio-temporal nonuniformities in H_{2} oxidation on individual Rh(\textit{h k l}) domains of a polycrystalline Rh foil were studied in the 10^{–6} mbar pressure range by photoemission electron microscopy (PEEM), X-ray photoemission electron microscopy (XPEEM), and low-energy electron microscopy (LEEM). The latter two were used for in situ correlative microscopy to zoom in with significantly higher lateral resolution, allowing detection of an unusual island-mediated oxygen front propagation during kinetic transitions. The origin of the island-mediated front propagation was rationalized by model calculations based on a hybrid approach of microkinetic modeling and Monte Carlo simulations.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Troester2022,

title = {Hard antiphase domain boundaries in strontium titanate unravelled using machine-learned force fields},

author = {Andreas Tröster and Carla Verdi and Christoph Dellago and Ivan Rychetsky and Georg Kresse and Wilfried Schranz},

doi = {10.1103/physrevmaterials.6.094408},

year  = {2022},

date = {2022-09-16},

urldate = {2022-09-16},

journal = {Physical Review Materials},

volume = {6},

number = {9},

pages = {094408},

publisher = {American Physical Society (APS)},

abstract = {We investigate the properties of hard antiphase boundaries in SrTiO_{3} using machine-learned force fields. In contrast to earlier findings based on standard \textit{ab initio} methods, for all pressures up to 120kbar the observed domain wall pattern maintains an almost perfect Néel character in quantitative agreement with Landau-Ginzburg-Devonshire theory, and the in-plane polarization P_{3} shows no tendency to decay to zero. Together with the switching properties of P_{3} under reversal of the Néel order parameter component, this provides hard evidence for the presence of rotopolar couplings. The present approach overcomes the severe limitations of \textit{ab initio} simulations of wide domain walls and opens avenues toward concise atomistic predictions of domain-wall properties even at finite temperatures.},

keywords = {P03, P12},

pubstate = {published},

tppubtype = {article}

}

@article{Wanzenboeck2022,

title = {Neural-network-backed evolutionary search for SrTiO_{3}(110) surface reconstructions},

author = {Ralf Wanzenböck and Marco Arrigoni and Sebastian Bichelmaier and Florian Buchner and Jesús Carrete and Georg K. H. Madsen},

doi = {10.1039/d2dd00072e},

year  = {2022},

date = {2022-08-26},

journal = {Digital Discovery},

volume = {1},

number = {5},

pages = {703--710},

publisher = {Royal Society of Chemistry (RSC)},

abstract = {The determination of atomic structures in surface reconstructions has typically relied on structural models derived from intuition and domain knowledge. Evolutionary algorithms have emerged as powerful tools for such structure searches. However, when density functional theory is used to evaluate the energy the computational cost of a thorough exploration of the potential energy landscape is prohibitive. Here, we drive the exploration of the rich phase diagram of TiO_{x} overlayer structures on SrTiO_{3}(110) by combining the covariance matrix adaptation evolution strategy (CMA-ES) and a neural-network force field (NNFF) as a surrogate energy model. By training solely on SrTiO_{3}(110) 4×1 overlayer structures and performing CMA-ES runs on 3×1, 4×1 and 5×1 overlayers, we verify the transferability of the NNFF. The speedup due to the surrogate model allows taking advantage of the stochastic nature of the CMA-ES to perform exhaustive sets of explorations and identify both known and new low-energy reconstructions.},

keywords = {P09},

pubstate = {published},

tppubtype = {article}

}

@article{TAMPIERI2022121889,

title = {Catalytic aldol condensation of bio-derived furanic aldehydes and acetone: Challenges and opportunities},

author = {Alberto Tampieri and Karin Föttinger and Noelia Barrabés and Francesc Medina},

url = {https://doi.org/10.1016/j.apcatb.2022.121889

https://www.sciencedirect.com/science/article/pii/S092633732200830X},

doi = {10.1016/j.apcatb.2022.121889},

year  = {2022},

date = {2022-08-24},

urldate = {2022-08-24},

journal = {Applied Catalysis B: Environmental},

volume = {319},

number = {121889},

abstract = {Bio-derived furfural and 5-hydroxymethylfurfural can be combined with acetone to yield aldol condensation products that may serve as biofuel and polymer precursors. We have explored different catalytic systems to obtain and purify each product in the most efficient way. The results of the catalytic tests of the cross-condensations and of the self-condensation of acetone allowed the comparison of the different reactivity of the two aldehydes. Online and in situ/operando ATR-IR was used to monitor the reaction over time and to study the interaction of the reaction species with the solid catalyst, especially the formation of deactivating organic matter that covers the surface, which is a major issue in heterogeneous condensation processes. In situ NMR was used to study the ongoing reaction, assessing its stereoselectivity, and to study the behavior of deuterated species in the catalytic system. Finally, the preparation of C14, a hetero-double-condensation product, was also explored.},

keywords = {P10},

pubstate = {published},

tppubtype = {article}

}

@article{Wang2022,

title = {Surface chemistry on a polarizable surface: Coupling of CO with KTaO _{3}(001)},

author = {Zhichang Wang and Michele Reticcioli and Zdenek Jakub and Igor Sokolović and Matthias Meier and Lynn A Boatner and Michael Schmid and Gareth S. Parkinson and Ulrike Diebold and Cesare Franchini and Martin Setvin},

url = {https://www.science.org/doi/10.1126/sciadv.abq1433},

doi = {10.1126/sciadv.abq1433},

year  = {2022},

date = {2022-08-19},

urldate = {2022-08-19},

journal = {Science Advances},

volume = {8},

issue = {33},

publisher = {American Association for the Advancement of Science (AAAS)},

abstract = {Polarizable materials attract attention in catalysis because they have a free parameter for tuning chemical reactivity. Their surfaces entangle the dielectric polarization with surface polarity, excess charge, and orbital hybridization. How this affects individual adsorbed molecules is shown for the incipient ferroelectric perovskite KTaO_{3}. This intrinsically polar material cleaves along (001) into KO- and TaO_{2}-terminated surface domains. At TaO_{2} terraces, the polarity-compensating excess electrons form a two-dimensional electron gas and can also localize by coupling to ferroelectric distortions. TaO_{2} terraces host two distinct types of CO molecules, adsorbed at equivalent lattice sites but charged differently as seen in atomic force microscopy/scanning tunneling microscopy. Temperature-programmed desorption shows substantially stronger binding of the charged CO; in density functional theory calculations, the excess charge favors a bipolaronic configuration coupled to the CO. These results pinpoint how adsorption states couple to ferroelectric polarization.},

keywords = {P02, P04, P07},

pubstate = {published},

tppubtype = {article}

}