Investigating the role of catalyst activity in nanocatalysed self-oscillating chemical reactions via bifurcation analyses

Reaction-Diffusion (RD) based self-sustained oscillatory reactions have been used to design various biomimetic stimuli-responsive systems. Belousov Zhabotinsky (BZ) reactions are nonlinear chemical oscillators, that undergo periodic oscillations due to redox-cycle of metal-ion catalyst, by virtue of Hopf bifurcation. Recently, we have shown that the kinetics of BZ reaction is enhanced by using heterogenous nanocatalysts, namely, Ce/Ru nanoparticles decorated graphene nanocomposites and bare Ce nanosheets. Moreover, the kinetics of these nanocatalysed BZ reaction can be modelled by introducing catalyst activity in the Oregonator model. Here, we use bifurcation analysis to investigate the role of catalytic activity on the oscillatory characteristics of BZ reaction. In particular, we compute higher order Lyapunov and frequency coefficients, with catalytic activity as the bifurcation parameter, to determine oscillatory regimes, amplitude and frequency of BZ oscillations. Our investigations reveal re-entrant regions in the bifurcation diagram where sustained oscillations are unexpectedly suppressed, even with high catalytic activity. Our findings can be used to exploit nonlinearity of RD based dynamical systems for biomimetic applications.