Deuterium isotope effect on the induction period of the cerium catalyzed Belousov–Zhabotinsky reaction

Hofmeister Effect in Self-Organized Chemical Systems

We studied the effect of spectator ions in the prototype of far-from-equilibrium self-organized chemical systems, the Belousov-Zhabotinsky (BZ) reaction. In particular, we investigated the specific ion effect of alkali metal cations, connoted for their kosmotropic and chaotropic properties. By means of combined experimental and numerical approaches, we could show a neat and robust evidence for the Hofmeister effect in this system. Spectator cations induce a marked increment of the induction period that preludes regular oscillations and decrease the oscillation amplitude following the sequence Li⁺ < Na⁺ ≪ K⁺ ∼ Cs⁺. These ions affect the system kinetics by interfering in the interaction between the oxidized form of the catalyst and the organic substrate, responsible for resetting the BZ system to pre-autocatalytic (reduced) conditions. The specific ion effect on these key reactive steps is systematically characterized and correlated with different parameters which describe the interaction of the cations with the solvent.

Time-periodic oscillation reaction in an organic-solvent dominated electrolyte

Time-periodic phenomena widely exist in natural life sustaining systems but are rarely reported in highly efficient artificial electrochemical energy-harvesting systems. Herein, we observed for the first time the periodic oscillation reaction in organic-solvent dominated electrolytes that could be also derived from some electrochemical energy harvesting cells. Owing to different reaction activity and acidity in the organic solvent, the oscillation reaction could occur under milder pH conditions and exhibit better durability. Its influence on electric output and related differences from an aqueous B-Z reaction are discussed from a mechanism point of view. Our findings may contribute to smart self-oscillation materials and new strategies for highly efficient long-term energy harvesting.