Dynamics of Janus motors with microscopically reversible kinetics

TL;DR

This paper develops a microscopic reversible kinetic model for Janus motors, enabling the study of their nonequilibrium dynamics and fluctuations, bridging microscopic reactions with macroscopic motor behavior.

Contribution

It introduces a reversible reaction model satisfying detailed balance, applicable to nonequilibrium steady states of Janus motors, extending understanding of their fluctuation properties.

Findings

Reversible reaction model satisfies detailed balance.

Generalized chemical rate laws describe equilibrium reaction rates.

Self-propelled Janus motors exhibit specific fluctuation characteristics.

Abstract

Janus motors with chemically active and inactive hemispheres can operate only under nonequilibrium conditions where detailed balance is broken by fluxes of chemical species that establish a nonequilibrium state. A microscopic model for reversible reactive collisions on a Janus motor surface is constructed and shown to satisfy detailed balance. The model is used to study Janus particle reactive dynamics in systems at equilibrium where generalized chemical rate laws that include time-dependent rate coefficients with power-law behavior are shown to describe reaction rates. While maintaining reversible reactions on the Janus catalytic hemisphere, the system is then driven into a nonequilibrium steady state by fluxes of chemical species that control the chemical affinity. The statistical properties of the self-propelled Janus motor in this nonequilibrium steady state are investigated and compared with predictions of a fluctuating thermodynamics theory. The model has utility beyond the examples presented here, since it allows one to explore various aspects of nonequilibrium fluctuations in systems with self-diffusiophoretic motors from a microscopic perspective.