  Motility-induced phase separation (MIPS) is a well-studied nonequilibrium
collective phenomenon observed in active particles. Recently, there has been
growing interest in how coupling the self-propulsion of active particles to
chemical degrees of freedom affects MIPS. Previous studies have shown that
incorporating chemotaxis and the production or consumption of chemicals by
active particles results in various pattern formations, such as arrested phase
separation and traveling waves. In this study, we demonstrate that similar
phenomena can be induced when active particles consume chemicals and exhibit
chemokinesis, where higher chemical concentrations enhance self-propulsion
without causing alignment with the chemical gradient. We discover that MIPS is
intensified if chemical consumption is proportional to particle density but is
suppressed if chemical consumption is closely tied to particle motion. This
leads to a wider range of collective behaviors, including arrested phase
separation and oscillating patterns. Our findings are based on a hydrodynamic
theory derived from a particle-based model via standard methods.
