## About

124

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Introduction

Additional affiliations

January 2010 - December 2014

**Ertl Center for Electrochemistry and Catalysis**

Position

- Vice Director

## Publications

Publications (124)

We present efficient algorithmic methods to detect Hopf bifurcation fixed points in chemical reaction networks with symbolic rate constants, thereby yielding information about the oscillatory behavior of the networks. Our methods use the representations of the systems on convex coordinates that arise from stoichiometric network analysis. One of our...

The co-existence of disparate time scales is pervasive in many systems. In particular for surface reactions, it has been shown that the long-term evolution of the core oscillator is decisively influenced by slow surface changes, such as progressing deactivation. Here we present an in-depth numerical investigation of the coupled slow and fast surfac...

Neste trabalho, a eletrooxidação oscilatória de ácido fórmico (FA) é investigada sobre paládio policristalino e comparada a resultados obtidos sobre platina policristalina; as principais diferenças entre ambas as superfícies são atribuídas a diferentes cinéticas da sub-rede química tanto quanto a rotas preferenciais admitidas sobre a superfície de...

We build on our previous work to compute Hopf bifurcation fixed points for chemical reaction systems on the basis of reaction co-ordinates. For determining the existence of Hopf bifurcations the main algorithmic problem is to determine whether a single multivariate poly-nomial has a zero for positive coordinates. For this purpose we provide heurist...

We build on our previous work to compute Hopf bifurcation fixed points for chemical reaction systems on the basis of reaction co- ordinates. For determining the existence of Hopf bifurcations the main algorithmic problem is to determine whether a single multivariate poly- nomial has a zero for positive coordinates. For this purpose we provide heuri...

Electrochemical reactions exhibit autosustained oscillatory states once the appropriate parameters are applied. As shown herein, the main impact of operating a reaction in an oscillatory state is the increased efficiency. The electroxidation of CO-containing hydrogen is analyzed because its oscillating mechanism mimics the oscillator known as hidde...

The problem of non-stationarity in experimentally recorded time-series is common in many (electro)chemical systems. Underlying this non-stationarity is the slow drift in some uncontrollable parameter, and it occurs in spite of the fact that all controllable parameters are kept constant. Particularly for electrochemical systems, some of us have rece...

The analysis of dynamic of chemical reaction networks by computing Hopf bifurcation is a method to understand the qualitative behavior of the network due to its relation to the existence of oscillations. For low dimensional reaction systems without additional constraints Hopf bifurcation can be computed by reducing the question of its occurrence to...

Kinetic investigations in the oscillatory state have been carried out in order to shed light on the interplay between the complex kinetics exhibited by a proton exchange membrane fuel cell fed with poisoned H(2) (108 ppm of CO) and the other in serie process. The apparent activation energy (E(a)) in the stationary state was investigated in order to...

Concepts from algebraic geometry (polynomial rings) can be used to determine analytically the stationary solutions in chemical reaction systems, more generally, systems of ordinary differential aligns of polynomial form. The stability analysis via the Jacobian matrix often leads to complicated expressions which can hardly be analyzed. It is shown t...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Low-index plane Pt single crystal electrodes modified by submonolayer deposition of Sn have been tested for ethanol oxidation in acidic media using cyclic voltammetry and chronoamperometry. The enhancement factor for ethanol oxidation depends on both substrate crystallography and Sn coverage. The optimum coverage was found to be around 0.2, 0.25 an...

A mechanism for the kinetic instabilities observed in the galvanostatic electro-oxidation of methanol is suggested and a model developed. The model is investigated using stoichiometric network analysis as well as concepts from algebraic geometry (polynomial rings and ideal theory) revealing the occurrence of a Hopf and a saddle-node bifurcation. Th...

Since the current density near the edges of ribbon and disk electrodes is enhanced, the resulting stationary and non-stationary double layer potential is generally inhomogeneous in all electrochemical reactions. We investigate the impact of this edge effect induced spatial inhomogeneity on the pattern formation of the oscillatory formic acid oxidat...

A systematic study of spiral waves in a realistic reaction-diffusion model describing the isothermal CO oxidation on Pt(110) is carried out. Spirals exist under oscillatory, excitable, and bistable (doubly metastable) conditions. In the excitable region, two separate meandering transitions occur, both when the time scales become strongly different...

We studied the open circuit interaction of methanol and ethanol with oxidized platinum electrodes using in situ infrared spectroscopy. For methanol, it was found that formic acid is the main species formed in the initial region of the transient and that the steep decrease of the open circuit potential coincides with an explosive increase in the CO2...

For the description of complex dynamics of open systems, an approach is given by different concepts of majorization (order structure). Discrete diffusion processes with both invariant object number and sink or source can be represented by the development of Young diagrams on lattices. As an experimental example, we investigated foam decay, dominate...

Three levels of modeling, microscopic, mesoscopic and macroscopic are discussed for the CO oxidation on low-index platinum
single crystal surfaces. The introduced models on the microscopic and mesoscopic level are stochastic while the model on the
macroscopic level is deterministic. It can be derived rigorously for low-pressure conditions from the...

In the present work the electrochemical pattern formation was investigated during electro-oxidation of formic acid on platinum electrode. The working electrode is quasi-one-dimensional ribbon polycrystalline platinum. The stationary domains (sDs) have been successfully captured after an external pulse was triggered. At a relatively high conductivit...

The use of a ribbon-shaped Pt electrode gives rise to edge effects of the interfacial potential, as is predicted from the potential theory in the form of the corresponding reaction-migration equation. They are studied in the bistable region of formic acid oxidation. Essentially, the edges tend to be more passive than the bulk of the electrode, whic...

IntroductionEssential and Nonessential SpeciesClassification of Oscillators and Role of Essential SpeciesApplication to Mechanistic StudiesDiscussion

Spontaneous nucleation, pulse formation and propagation failure have been observed experimentally in CO oxidation on Pt(110) at intermediate pressures ( ≈ 10 − 2 mbar). This phenomenon can be reproduced with a stochastic model that includes temperature effects. Nucleation occurs randomly due to fluctuations in the reaction processes, whereas the su...

Special structures in a chemical reaction network can give rise to bistability, oscillations, and chaos. It has been shown recently [A. Sensse and M. Eiswirth, J. Chem. Phys. 122, 044516 (2005)] that the introduction of an additional species in a supplementary feedback loop to a minimal autocatalytic oscillator gives rise to chaotic dynamics in a c...

We present a mathematical model for calcium oscillations in the cilia of olfactory sensory neurons. The underlying mechanism is based on direct negative regulation of cyclic nucleotide-gated channels by calcium/calmodulin and does not require any autocatalysis such as calcium-induced calcium release. The model is in quantitative agreement with avai...

A family of polynomial differential systems describing the behavior of a chemical reaction network with generalized mass action kinetics is investigated. The coefficients and monomials are given by graphs. The aim of this investigation is to clarify the algebraic-discrete aspects of a Hopf bifurcation in these special differential equations. We app...

A model for the electrocatalytic oxidation of formic acid is investigated. Because the reaction rates follow mass action and the Butler–Volmer rate law, the system is highly nonlinear. It is shown that the system can be solved analytically using recent methods from convex and toric geometry, enabling an exact stability analysis without fixing the k...

Previous investigations have revealed that special constellations of feedback loops in a network can give rise to saddle-node and Hopf bifurcations and can induce particular bifurcation diagrams including the occurrence of various codimension-two points. To elucidate the role of feedback loops in the generation of more complex dynamics, a minimal p...

It is shown that hyperchaos of order m (i.e., with m positive Lyapunov exponents) can be generated by a single feedback circuit in n = 2m + 1 variables. This feedback circuit is constructed such that, dividing phase space into hypercubes, it changes sign wherever the trajectory passes from one hypercube into an adjacent one. Letting the negative di...

The interaction of external noise with an electrochemical oscillator was experimentally analyzed on both sides of the homoclinic bifurcation. The autonomous system behavior was explored, before studying the noise provoked dynamics. The frequency of the periodic oscillation decreased as one approaches the bifurcation point from the oscillatory side,...

Experimental observations of different spatiotemporal patterns of the interfacial potential on a bismuth modified platinum ring working electrode (WE) with different positions of the reference electrode (RE) in the electrocatalytic oxidation of formic acid are presented. For small distances between WE and RE, inhomogeneous patterns (e.g., standing...

Nonlinear dynamics in heterogeneous catalysis has been studied extensively over the past decades (see [[1]–[14]] for review articles). A large number of reactions, different types of catalysts and reactor designs have been used. In
general, an understanding of pattern formation on catalytic surfaces requires not only detailed knowledge of the react...

Experimental observations of temporal dynamics in the electrocatalytic oxidation of methanol (CH3OH) on a polycrystalline platinum electrode are reported, Hidden negative differential resistance (HNDR) and instabilities of the system were investigated by means of an electrochemical impedance spectrum analysis and potential oscillations under galvan...

We describe the generation of new limit cycles in electrochemical systems under the influence of external periodic perturbations. For certain specific parameters of a nonharmonic forcing function, two coexisting periodic orbits can be generated from a single limit cycle observed in the unperturbed dynamics. This inception of birhythmicity (bistabil...

The spatial coupling in electrochemical systems is mediated by ion migration under the influence of the electric field. Since field effects spread very rapidly, every point of an electrode can communicate with every other one practically instantaneously through migration coupling. Based on mathematical potential theory we present the derivation of...

We present spatiotemporal mixed-mode oscillations in the electrocatalytic oxidation of formic acid on a platinum ring electrode modified by bismuth deposition. On the anodic scan, we observed spontaneous reversal of direction of a rotating activation pulse occurring repeatedly at the same location of the ring. In the constant potential method, spat...

Oscillatory rotating activation pulses on a Pt ring electrode during formic acid oxidation were externally perturbed via a trigger electrode at one location of the ring. While usual phase resetting was obtained for small perturbation amplitudes, stronger perturbations resulted in reversal of the direction of pulse motion when applied behind the pul...

We report experimental observations on the temporal dynamics in the electrocatalytic oxidation of formic acid (HCOOH) on a polycrystalline Pt electrode modified by deposition of bismuth. Bismuth modification significantly enhanced the current density of HCOOH oxidation, since it suppressed the poisoning branch and increased the apparent direct oxid...

We present a general model for the oxidation of CO on low-index platinum single crystal surfaces. In order to take fluctuations into account, it is first formulated in terms of stochastic birth–death processes. A corresponding deterministic limit for large particle numbers can be derived rigorously. The dynamical behavior of the reaction kinetics i...

We report experimental observations of the spatio-temporal dynamics in the electro-oxidation of formic acid on a Pt ring electrode modified by bismuth adatoms. Bismuth modification significantly enhanced the current density and it was found to considerably increase the existence range of oscillations and spatio-temporal self-organization. Hidden ne...

We use nonlinear signal processing techniques, based on artificial neural networks, to construct a continuous-time model (set of ordinary differential equations, ODEs) from experimental observations of mixed-mode oscillations during the galvanostatic oxidation of hydrogen on platinum in the presence of bismuth and chloride ions. The data was in the...

We report results (numerical and experimental) indicating control of the observed oscillatory dynamics in an electrochemical system using external forcing and variable feedback. Under the influence of external forcing it was observed that the chaotic dynamics could be converted to periodic states. Moreover, regular states with different periodiciti...

We report results (numerical and experimental) indicating control of the observed oscillatory dynamics in an electrochemical system using external forcing and variable feedback. Under the influence of external forcing it was observed that the chaotic dynamics could be converted to periodic states. Moreover, regular states with different periodiciti...

Experimental standing wave oscillations of the interfacial potential across an electrode have been observed in the electrocatalytic oxidation of formic acid on a Pt ring working electrode. The instantaneous potential distribution was monitored by means of equispaced potential microprobes along the electrode. The oscillatory standing waves spontaneo...

We consider a comprehensive classification scheme of oscillatory electrochemical systems with respect to the mechanistic basis of their kinetic instability. Four principal oscillator categories are distinguished depending on the mechanistic role of the potential drop across the electrode ∣ electrolyte interface (double layer potential) and of the c...

Turing-like patterns formed during the polymerization of acrylamide in the presence of sulfide, methylene blue and molecular oxygen are presented. We propose a chemical model of the polymerization of acrylamide in the presence of sulfide and oxygen. The model explains the formation of Turing patterns in this system. The experimental process of patt...

The influence of the concentration of chloride ions on the underpotential deposition of copper onto Pt(111) has been studied by AES, LEED and RHEED. The results demonstrate that the arrangements of the superlattices of (2×3), ‘(4×4)’, c(11×3) and (1821), and their packing density on the copper covered Pt(111) are clearly determined by the Cl− conce...

The electrochemical deposition of Ru on Pt(111) electrodes has been investigated by electron diffraction, Auger spectroscopy, and cyclic voltammetry in a closed UHV transfer system. At small coverages Ru formed a monatomic commensurate layer, at higher coverage mostly small islands with a bilayer height were detected. When the Pt was almost complet...

In the potentiostatic electrochemical oxidation of formic acid on a platinum ring electrode under bistable conditions, an
appropriate perturbation at one location of the ring can cause the emergence of a wave on the opposite side (remote triggering).
These findings can be rationalized in terms of the nonlocal coupling function of the system and are...

Pattern formation during the oscillatory electrodissolution of Co was studied using a Co ring electrode with a small reference electrode at a short distance in the center of the ring. Traveling pulses as well as source points (one-dimensional target patterns) were observed. These findings could be reproduced using a reaction-migration equation (RME...

Experiments on the catalytic reduction of NO with CO on a Pt(100) surface reveal attractive interaction between pulses leading to the eventual merging of two pulses to a single one. The results can be reproduced with a realistic reaction-diffusion model which yields a negative slope in the dispersion relation over a large range of the interpulse di...

An experimental and theoretical description of the oscillatory electrocatalytic iodate reduction system in alkaline solution is presented. Experimental measurements suggested the crucial role of a negative differential resistance as well as the presence of hydrogen evolution in the oscillatory instability. A simple kinetic model with one chemical s...

The underpotential deposition (UPD) of copper on to Pt(111) in the presence of chloride anions was studied by full-dynamical LEED-intensity analyses. A deformed (4×4) LEED pattern was observed at an emersion potential of 0.36V vs. Ag/AgCl, right in between the two characteristic and well-separated peaks of the cyclic voltammogram (CV). Correspondin...

Derivative control was applied to electrochemical oscillators under potentiostatic as well as galvanostatic conditions; i.e., the time derivative of a measured quantity (such as the current or the concentration of an electrochemical species) is fed back to the externally applied voltage or, respectively, current. In particular cases the control led...

We address the stability of solitary pulses as well as some other traveling structures near the onset of spatiotemporal chaos in a two-species reaction-diffusion model describing the oxidation of CO on a Pt(1 1 0) surface in one spatial dimension. First, the boundary of the existence region of stable pulses is explored by means of numerical integra...

The experimental characterization of the current/outer potential (I/U) behavior during the electrochemical CO oxidation on Pt(100), Pt(110) and Pt(111) is used as the first step towards a thorough investigation of the processes occurring during the electrochemical formic acid oxidation. The CO study is followed by new cyclovoltammetric results duri...

A kinetic model is developed for the electrocatalytic oxidation of formic acid on Pt under potentiostatic control. The model development proceeds stepwise via a simple model of the electrocatalytic CO oxidation. The full model consists of four coupled, nonlinear ordinary differential equations. The scanned and stationary current/outer potential (I/...

We report the suppression of spatiotemporal chaos observed in coupled
map lattices. Suppression is achieved using different feedback
techniques, most of which are applicable to actual experimental
situations. Results from application of feedback control to a single
chaotic element (single map) are presented to demonstrate similarities
in the dynami...

Sufficient and necessary conditions for the occurrence of a Hopf bifurcation in chemical reaction mechanisms are presented using the formalism of stoichiometric networks. The conditions are applied to determine the mechanistic basis of chemical oscillations in isothermal surface reactions. Realistic examples are given for the different oscillatory...

We report the stabilization of unstable fixed points (saddles) in model systems exhibiting bistability. Stabilization is achieved using the derivative control strategy proposed in a different context by Biewlaski et al. (Phys. Rev. 1993, A47, 3276). This strategy does not change the location of fixed points in the system, but does alter their stabi...

In certain nonlinear systems, under appropriate conditions, the dynamical behavior switches intermittently between two distinct chaotic states. We report the stabilization of the dynamics on a desired chaotic state using an occasional feedback control via a map-based algorithm which can be easily implemented in experimental situations where only on...

A time series of the catalytical reaction of CO and O2 on a Pt(110) surface is used to model the topological features of the underlying attractor by reconstructing unstable periodic orbits in a three-dimensional imbedding space. The orbits reveal that the template supporting the dynamics cannot be that of a Smale's horseshoe. Some of the computed o...

Numerical simulations and analytical arguments for the resonant behavior of periodically perturbed rotating spiral waves in systems with broken rotational symmetry are presented. Resonance, i.e., the displacement of the rotation center along a straight line, appears always if the perturbed rotation does not match the symmetry given by the active me...

A time series of the catalytical reaction of CO and ${\mathrm{O}}_{2}$ on a Pt(110) surface is used to model the topological features of the underlying attractor by reconstructing unstable periodic orbits in a three-dimensional imbedding space. The orbits reveal that the template supporting the dynamics cannot be that of a Smale's horseshoe. Some o...

A recently proposed model to describe the galvanostatic oscillating oxidation of hydrogen on Pt in the presence of copper and chloride is also able to explain the potentiostatic behaviour of the experimental system. For sufficiently high series resistance it exhibits current oscillations on a branch where the stationary current-voltage curve has a...

The transition between rotating spirals and spatiotemporal chaos (``spiral turbulence'') in an excitable reaction-diffusion system is investigated by means of statistics of topological defects of the concentration field. The ratio of the variance and the mean value of the number of defects show a significant deviation from unity at this point. A ch...

Experiments with an anisotropic chemical excitable medium—a catalytic chemical reaction on a single crystal surface—reveal a kind of stable wave pattern representing single traveling-wave fragments. Their existence is attributed to the presence of a strong state-dependent diffusion anisotropy in the medium. A simple theory of traveling fragments se...

The dynamics of a large number of heterogeneously catalyzed reactions have been studied under a variety of conditions using different catalysts and reactor designs. Experiments with single crystal surfaces at low pressure are required in order to elucidate the underlying elementary chemical steps. Here we present a case study of such an approach us...

A simple model of the galvanostatic oscillations that occur during the oxidation of hydrogen at platinum electrodes in the presence of electrosorbing metal ions and specifically adsorbing anions is presented. It consists of three ordinary differential equations describing the degree of coverage of the electrode with underpotential-deposited metal a...

The transition between wave fronts and spiral waves in the CO oxidation on a Pt(110) surface has been investigated by means of photoemission electron microscopy and treated theoretically by simulations with a reaction-diffusion model under bistable conditions. Periodic external forcing of spirals near the transition to front behavior led to a compl...

We studied the oscillatory galvanostatic H2-oxidation on the three low-index Pt surfaces in the presence of Cu2+ and different electrolytes: H2SO4, H2SO4 + Cl− and H2SO4 + Br−. It was found that both surface orientation of the Pt-electrode as well as the nature of the anions strongly influence the dynamics. Halide ion adsorption plays an essential...

In the reduction of NO with H2 on a Rh(110) surface rectangularly shaped target patterns and spirals with sharp corners have been observed. These patterns can be reproduced with a simple model assuming that the (anisotropic) diffusion is state dependent. Such a dependence is realized in the system Rh(110)/NO +H2 by the presence of different adsorba...

Rigidly rotating spiral waves under constant external parameters, drifting spirals under the influence of a periodic perturbation as well as turbulent patterns have been observed in the isothermal CO oxidation on a Pt(1 1 0) single crystal surface. A simple reaction-diffusion model can reproduce these findings. It is pointed out that the spiral res...

Over the past few decades, heterogeneous catalysis has been found to provide a very rich variety of phenomena of spatiotemporal selforganization (see the review articles [1–12] and references therein). Thus multistability, oscillatory behavior and chaos have been found on all levels, from whole reactors over individual pellets to single crystal sur...

Among heterogeneously catalyzed chemical reactions, the CO oxidation on the Pt(110) surface under vacuum conditions offers probably the greatest wealth of spontaneous formation of spatial patterns. Spirals, fronts, and solitary pulses were detected at low surface temperatures (T<500 K), in line with the standard phenomenology of bistable, excitable...

The electrochemical oxidation of formic acid under potentiostatic conditions was found to exhibit transient oscillations on all three low-index plane Pt surfaces in an unstirred electrolyte. Depending on structure, substantial differences occurred concerning induction time, oscillation period, and shape as well as number of oscillations. Stirring c...

A systematic study of spiral waves in a realistic reaction-diffusion model describing the isothermal CO oxidation on Pt(110) is carried out. Spirals exist under oscillatory, excitable, and bistable (doubly metastable) conditions. In the excitable region, two separate meandering transitions occur, both when the time scales become strongly different...

A systematic study of spiral waves in a realistic reaction-diffusion model describing the isothermal CO oxidation on Pt(110) is carried out. Spirals exist under oscillatory, excitable, and bistable (doubly metastable) conditions. In the excitable region, two separate meandering transitions occur, both when the time scales become strongly different...

In the reduction of NO with H2 on a Rh(110) surface rectangularly shaped target patterns and spirals with sharp corners have been observed. These patterns can be reproduced with a simple model assuming that the (anisotropic) diffusion is state dependent. Such a dependence is realized in the system Rh(110)/NO + H2 by the presence of different adsorb...

Excitable media are extended spatial systems, which support the propagation of waves including pulses and rotating spirals. They are well described by sets of partial differential equations involving a fast activator and a slow inhibitor variable. Here we show that spiral breakup, leading to turbulence, can occur in a two-dimensional reaction-diffu...

A refined version of the Sano-Sawada algorithm to compute Lyapunov spectra has been implemented and tested with several models, which include periodic, chaotic and hyperchaotic attractors, under conditions designed to mimic experimental situations. It was found that reliable Lyapunov exponents can be obtained for time series of moderate length and...

The dynamic behavior of the electrocatalytic oxidation of hydrogen on a platinum anode in the presence of Cu2+ and Cl- ions under galvanostatic conditions has been studied experimentally in two control parameters: current density and copper ion concentration. This parameter plane can roughly be divided into three broad regions: A steady state is fo...

We present a dynamic model for the oscillatory reduction of anions such as S2O82− on different electrodes. The model is solely based on well known electrochemical formulae so that the mechanism can be well understood. The central mechanistic feature is a region of negative differential resistance in the cathodic current/overvoltage curve. It is cau...

A dynamic model designed to describe bistability and kinetic oscillations of the reaction rate during the oxidation of CO on a Pt(110) single crystal surface is extended by incorporating surface diffusion of adsorbed CO in order to analyze the properties of traveling waves propagating on the catalytically active surface. In the range of control par...

A simple reaction-diffusion model for the CO oxidation on Pt(110), exhibiting among other features bistability and oscillations, is studied in an excitable parameter region where traveling solitary pulses with high O coverage may be formed on an otherwise CO-covered surface. If it is assumed that small patches are structurally imperfect, effects of...

A kinetic model of the catalytic CO oxidation on a Pt(110) surface is used to describe effects of spatiotemporal self-organization, which have been observed experimentally with this system. After some simplification and taking advantage of the strong separation of fast and slow variables the model can be used to obtain analytical expressions for fr...

The periodically perturbed oscillations in the isothermal CO oxidation on a Pt(110) surface at low pressure were modeled using the recently developed reconstruction model of kinetic oscillations, in which the usual Langmuir–Hinshelwood mechanism is coupled with the CO-driven 1×2&rlarr2;1×1 phase transition of the surface. The experimental findings...

The parameters entering the kinetics for the mechanism of catalytic CO oxidation have been adapted for a Pt(110) surface, giving rise to a two‐variable model correctly predicting bistability. Oscillations are obtained when, in addition, the adsorbate‐driven 1×2–1×1 structural phase transition of Pt(110) is taken into account. Mixed‐mode oscillation...

A two‐variable Langmuir–Hinshelwood mechanism for isothermal CO oxidation on a catalytically active surface is presented. It shows bistability stemming from 2 cusp bifurcations, which can be obtained analytically for low pressure. Inclusion of CO diffusion on the surface leads to a system of partial differential equations, which exhibits nucleation...

Time series from the oscillatory CO oxidation on a Pt(110) surface, which exhibit a period-doubling transition to chaos, have been analyzed using an algorithm to compute all Lyapunov exponents. Near the onset of chaos one positive exponent is obtained, while two positive exponents were obtained farther away from the onset, demonstrating the occurre...

The electrocatalytic oxidation of hydrogen in the presence of Cu2+ and Cl− ions under galvanostatic conditions has been studied on the three low-index plane surfaces of platinum. Over the parameter ranges investigated and with the electrode pretreatment used, no oscillations were observed on Pt(110), whereas only simple periodic oscillations were s...