Multiscale analysis of heat-mass-reaction coupling in the controlled synthesis of graphene oxide via heart-shaped microchannels

Abstract

Precise regulation of the oxidation degree of graphene oxide (GO) is critical for tailoring its physicochemical properties and expanding its applications. In this work, a heart-shaped microchannel was designed to achieve controlled GO synthesis via geometry-induced heat-mass-reaction coupling. A multiscale simulation strategy integrating the Discrete Phase Model (DPM), Discrete Element Method (DEM), and Reactive Molecular Dynamics (RMD) was developed to uncover the underlying mechanism. Increasing the inlet velocity from 0.025 m/s to 1.0 m/s enhanced the maximum shear rate and wall heat flux, accelerating convective heat transfer and mass mixing in the bifurcation and recombination zones. The higher flow velocities induced stronger interparticle and wall contact forces, potentially facilitating graphite fragmentation. Experimental results demonstrated that as the flow velocity decreases (from 1.0 m/s to 0.025 m/s), the O/C ratio decreases from 0.44 to 0.21, showing good agreement with the oxidation trend predicted by the RMD simulations (from 0.43 to 0.28). This study establishes a geometry-guided, multiphysics-multiscale framework for the rational design of microchannel systems for nanomaterial synthesis.