Nascimento Melke A, Nagao Raphael, Eiswirth Markus, Varela Hamilton
Institute of Chemistry of São Carlos, University of São Paulo, PO Box 780, 13560-970, São Carlos, SP, Brazil.
Fritz Haber Institute of the Max Planck Society, Department of Physical Chemistry, Faradayweg 4-6, D-14195 Berlin, Germany.
J Chem Phys. 2014 Dec 21;141(23):234701. doi: 10.1063/1.4903172.
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 surface dynamics in an electrocatalytic oscillator. The model consists of four nonlinear coupled ordinary differential equations, investigated over a wide parameter range. Besides the conventional bifurcation analysis, the system was studied by means of high-resolution period and Lyapunov diagrams. It was observed that the bifurcation diagram changes considerably as the irreversible surface poisoning evolves, and the oscillatory region shrinks. The qualitative dynamics changes accordingly and the chaotic oscillations are dramatically suppressed. Nevertheless, periodic cascades are preserved in a confined region of the resistance vs. voltage diagram. Numerical results are compared to experiments published earlier and the latter reinterpreted. Finally, the comprehensive description of the time-evolution in the period and Lyapunov diagrams suggests further experimental studies correlating the evolution of the system's dynamics with changes of the catalyst structure.
不同时间尺度的共存现象在许多系统中普遍存在。特别是对于表面反应，研究表明，核心振荡器的长期演化受到缓慢表面变化（如渐进失活）的决定性影响。在此，我们对电催化振荡器中耦合的慢表面动力学和快表面动力学进行了深入的数值研究。该模型由四个非线性耦合常微分方程组成，在广泛的参数范围内进行了研究。除了传统的分岔分析外，还通过高分辨率周期图和李雅普诺夫图对该系统进行了研究。结果发现，随着不可逆表面中毒的发展，分岔图发生了显著变化，振荡区域缩小。定性动力学相应改变，混沌振荡得到显著抑制。然而，在电阻与电压图的一个受限区域内，周期级联得以保留。将数值结果与早期发表的实验进行了比较，并对后者进行了重新解释。最后，在周期图和李雅普诺夫图中对时间演化的全面描述表明，需要进一步开展实验研究，以关联系统动力学的演化与催化剂结构的变化。
